Agronomy for Sustainable Development

Published by Springer Verlag
Online ISSN: 1773-0155
Publications
Possible pathways of N transfer between legumes and grasses. 1. Direct transfer through mycorrhizal hyphae, 2. Degradation and decay of legume dead tissues or 3. Nitrogen exudation by living legume cells. N coming from degradation of plant tissues and from exudation can be taken up by grass in the form of ammonium or amino acids.  
Effect of potassium nitrate (KNO 3 ) concentration of the nutrient solution on concentration of ammonium (A) and total amino acids (B) in the solution surrounding roots of clover, control ryegrass and receiver ryegrass. Exudates were collected three times a week. Each value is the average concentration of ammonium and amino acids in the solution surrounding the roots over the experimental period, from day 47 to day 87 for clover, and from day 29 to day 69 for ryegrass. Data are means (± standard error) of five independent replicates and each replicate consisted of two plants grown in individual microlysimeters. Ammonium concentration in the root bathing solution of clover was not significantly modified by increasing nitrate concentration of the nutrient solution, but decreased in the root bathing solution of ryegrass. No effect of N application on the amounts of total amino acids exuded was observed throughout the experiment for clover or ryegrass.  
Individual amino acid N as % of total free amino acids of root exudates collected from clover (A) or receiver ryegrass (B) grown on increasing concentration of potassium nitrate (KNO 3 ) in the nutrient solution. Exudates were collected three times a week. Each value is the average percentage of amino acid N in exudates collected over the experimental period, from day 47 to day 87 for clover, and from day 29 to day 69 for ryegrass. Data are means (± standard error) of five independent replicates and each replicate consisted of two plants grown in individual microlysimeters. The concentration of most of the amino acids of the root bathing solution was independent of root content, except for asparagine.  
Effect of N fertilisation rate on concentration of nitrate (A), ammonium (B) and total free amino acids (C) in the rhizosphere soil solution of clover, ryegrass or clover – ryegrass mixture. Data are means (± standard error) of four independent replicate pots of eight plants each. N0: no fertilisation; N50: 50 kg N ha −1 ; N180: 180 kg N ha −1 . The highest ammonium and amino N concentrations in soil were found for clover grown without N input.  
Article
The overuse of classical N fertilisers contributes substantially to environmental degradation by pollution of groundwater by nitrates. This leaching of N in waters is also an economic flaw for farmers because only a part of the fertiliser is used by the plants. Here, systems involving mixtures of legumes and grasses represent a sustainable alternative because legumes can fix atmospheric N2 using symbiotic microbes. N transfer in those mixtures has been thoroughly investigated but little is known concerning the effect of N fertiliser on N transfer between N-fixing legumes and companion grasses. In white clover (Trifolium repens L.) — perennial ryegrass (Lolium perenne L.) associations, N is transferred mostly through rhizodeposition into the soil by clover followed by re-uptake by ryegrass. Rhizodeposition of N occurs through senescence and decomposition of legume tissue or through exudation of N compounds by living cells. Ammonium and amino acids are the main compounds exuded and their exudation is thought to occur by passive diffusion attributed to a concentration gradient from root to soil. In this study, we test the hypothesis that greater N transfer from clover to grass, as seen in N-rich soils or nutrient solutions, is due to greater N rhizodeposition brought about by higher ammonium and amino acid content of roots. The relations between N input, root N content, N net exudation and N transfer between legumes and grasses were investigated using 15N by growing white clover and perennial ryegrass with increasing N application in axenic microlysimeters or in pots. Ammonium and amino acid concentrations were measured in root tissues, in root bathing solutions and in soils. We found that mineral N application strongly reduced atmospheric N fixation by clover, from 3.0 to 0.9 mg per plant, and root amino acid content, from 164 to 49 nmoles per g dry weight, but had no effect on ammonium and amino acid concentrations in sterile exudates, showing for the first time that amino acid net exudation is independent of root content. In contrast, ammonium and amino acid concentrations in clover soils increased with N fixation, showing the link between N fixation and N rhizodeposition in soils. Nitrate application increased ryegrass root growth by 7–8 times, and transfer of N between clover and ryegrass (by 3 times). It is concluded that N fertiliser does not modify N exudation but decreases N fixation and ammonium rhizodeposition in soil by clover. N fertiliser increases N transfer between clover and ryegrass by increasing soil exploration by ryegrass and giving a better access to different available N sources, including the N compounds exuded from clover.
 
Article
In Réunion Island, expanding human populations, urbanization and agriculture during the last 50 years have all contributed to a steady increase in the level of nitrates in drinking water. Various nitrate point sources are responsible for the nitrate contamination around the island including chemical fertilizers, animal effluent applied to pasture and crops, and urban waste such as sewage and domestic waste water. In terms of agricultural fertilizers, pig effluent is the most widely used, but the cumulative effects of slurry applications on soil water and groundwater are unknown. Our objectives were (1) to characterize and follow in situ the fate of nitrogen through the subsurface after application of pig effluent onto a cultivated soil using stable nitrate isotopes, δ15N and δ18O, and (2) to compare the isotopic signatures of Réunion Island’s principal aquifers with results from the experimental site to infer potential contamination sources. The study was conducted on an experimental field site planted with maize in the western part of Réunion Island during the rainy season. A control site with no fertilizer application to the maize was compared with the investigation site which had pig effluent applied once a year. The site which had pig effluent applied over one year had an average maximum surface soil water 15N-NO 3− value of +9.0%o at 0.45 m depth. This signature was significantly more enriched in 15N than the corresponding subsurface soil water 15N-NO- 3− value of +3.8%o at 10 m depth. The control site average maximum surface soil water 15N-NO 3− value of +3.6%o at 0.45 m is similar to the subsurface pig effluent application plot. This indicates that nitrates derived from pig effluent have not reached 10 m depth in the subsurface, even though over the last 18 months this site was subjected to two effluent applications, each around 200 kg N ha−1, and more than 1900 mm of rain, more than half of which drains directly into the root zone. This slow migration shows that mobilization of nitrates through cultivated soil can take many tens of years before infiltrating and contaminating the saturated zone situated at several tens, and in places, hundreds of meters depth. On an island-wide scale, an isotopic assessment of nitrates from the experimental site’s soil water and other drinking water wells highlights a nitrogenous contamination derived primarily from urban and/or agriculture via effluent application.
 
Article
Management practices, geographical gradients and climatic factors are factors explaining weed species composition and richness in cereal fields from Northern and Central Europe. In the Mediterranean area, the precise factors responsible for weed distribution are less known due to the lack of data and surveys. The existence of weed survey data of year 1976 in the Zaragoza province of the Aragón region, Spain, offered us the opportunity to compare present weed species with weed species growing 30years ago. No detailed comparison of changes in weed species composition in cereal fields in that period of time has been conducted in the Mediterranean area. Here a survey was conducted in the Aragón region from 2005 to 2007. Weeds were surveyed in 138 winter cereal fields in ten survey areas where winter cereals are the main crops, using the same methodology applied 30years ago. In the Zaragoza province, 36 fields were chosen in the same municipalities than in the previous survey. Several management, geographic and climatic variables of each field were recorded and related to weed species with multivariate analysis. Diversity index were calculated and related to survey area and altitude. Our results show that out of the 175 species only 26 species were found in more than 10% of the surveyed fields. The main species were Papaver rhoeas, Lolium rigidum, Avena sterilis and Convolvulus arvensis found in more than half of the surveyed fields. L. rigidum was related to dryland, while the other species were found overall. Furthermore, we found that management, geographical and climatic factors were significantly related to weed species distribution. In particular altitude, survey areas, irrigation and herbicide use in post-emergence were the most driving factors explaining weed species distribution. Species richness was higher in survey areas with extensive management practices and increased with altitude excepting a very productive area with intensive management practices at high altitude where richness was as low as in the irrigated lowlands. The main differences found between the 1976 and the 2005–2007 surveys were (1) the striking increase of grass weeds, (2) the high decrease of mean weed species number found in each field declining from 9 to 3 and (3) the frequency decrease of many weed species probably caused by agriculture intensification in that period of time. The growing importance of other weed species is probably related to their adaptation to minimum tillage, which is a widespread technique nowadays. KeywordsBiodiversity–Canonical correspondence analysis–Rare weeds–Weed diversity
 
Article
The close links of climate, soil conditions, and agricultural productivity have been used in Central Europe for taxation purposes since the eighteenth century. Since agroclimatic conditions are variable, their fluctuations in the past centuries can provide a valuable context for analyzing changes expected in the coming decades. Here, historical agroclimatic conditions and future projections were constructed for key agricultural regions in Central Europe. The agroclimatic zoning method used in this study incorporates (1) the sum of temperatures for days with a mean temperature above 10°C during the frost-free period, (2) the water deficit during the summer period from June to August, defined as the difference between precipitation and reference evapotranspiration, and (3) information regarding the suitability of soil and terrain for agriculture production based on twentieth century soil surveys. Changes in selected agroclimatological indices were also analyzed. To produce a weather series representing climate conditions between 1803 and 2008 over the study area, we used a stochastic weather generator trained on high-quality daily observations from 52 representative meteorological stations during the baseline period from 1961 to 1990. To estimate the extent of agroclimatic zones and the values of selected agroclimatic indices, the parameters of the weather generator were perturbed by the deviations of the temperature and precipitation means from the baseline using a long-term climate series from 1803 to 2008, from Brno. To generate a weather series representing the climate in 2050, we used an approach known as “pattern-scaling” in combination with outputs of three general circulation models. To our knowledge, this is the first study analyzing both continuous fluctuations in agroclimatic conditions over the past 200 years and expected shifts in the coming decades over Central Europe. In the study region, our results demonstrate that changes in climate factors since the second half of the twentieth century have favored the expansion of warmer and drier agroclimatic conditions in the most fertile areas, progressively endangering the sustainability of rain-fed agriculture. Conversely, the agroclimatic conditions of regions at higher elevations have improved over the past six decades, as witnessed by increases in maize production areas but also an influx of previously absent pests, e.g., the European corn borer. The length of the vegetation summer has been increasing and shows daily average temperature exceeding 15°C. The mean number of days with snow cover has decreased by up to 30 days since a peak in the late nineteenth century. In lowland areas, the date of the last frost, with a 20-year return period, has moved closer to beginning of the season. Our results show that the predicted rate of change is unprecedented in available agroclimatic records; thus, adaptation cannot rely on past. Consequently, agricultural producers in the region will be forced to significantly bolster their adaptive capacity and develop flexible procedures that reflect the rapidly changing agroclimatic conditions.
 
Article
Low-input measures is used as a generic term for all measures involving a reduced intensity of agricultural management to enhance the quality of biotic or abiotic goods. Intensive agricultural regions have the lowest share of implemented low-input measures, though they have to resolve the most serious nature conservation and environmental problems. To understand the conditions for a better implementation of these measures in intensive agricultural areas, we carried out a written survey among 865 farmers in intensively-used arable regions. The adoption patterns of arable and grassland measures were compared. The determining factors were analysed by logistic regression. Arable measures, such as mulch seeding, that claim a high share of the arable area often have comparatively slight restrictions and cause windfall gains. However, our results show that their adoption increases the ratio of probability of a subsequent implementation of low-input measures on grasslands by 0.05. This means that these arable measures can act as starting measures for probably more valuable low-input measures on grasslands. Furthermore, the relation of the farmers with their subsidising institution proved to have an influence in our analysis. With every next best rating the farmers give for their relation with their subsidising institution, the ratio of probability for the adoption of low-input measures on arable land rises by 0.3. We also detected a strong positive influence of defined contact persons within the subsidising institution on the probability of adopting grassland measures, with a ratio of probability of 4.802. These findings show that the subsidising institution has in many respects a central influence on the decision process of the farmer to adopt low-input measures. The described determinants reveal new insights usable for improving the off-farm conditions of an increased implementation of low-input measures in intensively-used arable regions.
 
Predicted vapor pressure deficit (VPD) increase over a 100year period, starting with a baseline relative humidity (RH) of 45% and an average temperature of 25°C, and assuming three different scenarios: (1) a 3°C degree and a 1% RH increase over 100 years (small dash); (2) a 3°C degree and a 5% RH increase over 100 years (large dash); (3) a 3°C degree and a 10% RH increase over 100 years (continuous line)
Article
Humanity is heading toward the major challenge of having to increase food production by about 50% by 2050 to cater for an additional three billion inhabitants, in a context of arable land shrinking and degradation, nutrient deficiencies, increased water scarcity, and uncertainty due to predicted climatic changes. Already today, water scarcity is probably the most important challenge, and the consensual prediction of a 2–4°C degree increase in temperature over the next 100years will add new complexity to drought research and legume crop management. This will be especially true in the semi-arid tropic areas, where the evaporative demand is high and where the increased temperature may further strain plant–water relations. Hence, research on how plants manage water use, in particular, on leaf/root resistance to water flow will be increasingly important. Temperature increase will variably accelerate the onset of flowering by increasing thermal time accumulation in our varieties, depending on their relative responses to day length, ambient, and vernalizing temperature, while reducing the length of the growing period by increasing evapotranspiration. While the timeframe for these changes (>10–20years) may be well in the realm of plant adaptation within breeding programs, there is a need for today’s breeding to understand the key mechanisms underlying crop phenology at a genotype level to better balance crop duration with available soil water and maximize light capture. This will then be used to re-fit phenology to new growing seasons under climate change conditions. The low water use efficiency, i.e., the amount of biomass or grain produced per unit of water used, under high vapor pressure deficit, although partly offset by an increased atmospheric CO2 concentration, would also require the search of germplasm capable of maintaining high water use efficiency under such conditions. Recent research has shown an interdependence of C and N nutrition in the N performance of legumes, a balance that may be altered under climate change. Ecophysiological models will be crucial in identifying genotypes adapted to these new growing conditions. An increased frequency of heat waves, which already happen today, will require the development of varieties capable of setting and filling seeds at high temperature. Finally, increases in temperature and CO2 will affect the geographical distribution of pests, diseases, and weeds, presenting new challenges to crop management and breeding programs. KeywordsClimate change–Drought–Temperature increase–Vapor pressure deficit–Crop phenology–C/N balance–Simulation modeling–Climate variability–Pests–Disease
 
Soybean response to inoculation as regulated by the number of indigenous rhizobia (after Thies et al., 1991). 
Article
Low crop productivity is a general problem facing most farming systems in sub-Saharan Africa (SSA). These low yields are pronounced in grain legumes and are often associated with declining soil fertility and reduced N2-fixation due to biological and environmental factors. Unfortunately, the majority of African small farmers are now unable to afford the high mineral fertilizer prices. More than 75% of the fertilizers used in Africa are imported, putting pressure on foreign exchange. Low cost and sustainable technical solutions compatible with the socioeconomic conditions of small farmers are needed to solve soil fertility problems. Biological nitrogen fixation (BNF), a key source of N for farmers using little or no fertilizer, constitutes one of the potential solutions and plays a key role in sustainable grain legumes (e.g., soybean) production. Given the high cost of fertilizer in Africa and the limited market infrastructure for farm inputs, current research and extension efforts have been directed to integrated nutrient management, in which legumes play a crucial role. Inoculation with compatible and appropriate rhizobia may be necessary where a low population of native rhizobial strains predominates and is one of the solutions which grain legume farmers can use to optimize yields. It is critical for sustained yield in farmlands deficient in native rhizobia and where N supply limits production. Research on use of Rhizobium inoculants for production of grain legumes showed it is a cheaper and usually more effective agronomic practice for ensuring adequate N nutrition of legumes, compared with the application of N fertilizer. Here, we review past and ongoing interventions in Rhizobium inoculation (with special reference to soybean) in the farming systems of SSA with a view to understanding the best way to effectively advise on future investments to enhance production and adoption of BNF and inoculant technologies in SSA. The major findings are: (1) complete absence of or very weak institutions, policy and budgetary support for biotechnology research and lack of its integration into wider agricultural and overall development objectives in SSA, (2) limited knowledge of inoculation responses of both promiscuous and specifically nodulating soybean varieties as well as the other factors that inhibit BNF, hence a weak basis for decision-making on biotechnology issues in SSA, (3) limited capacity and lack of sustainable investment, (4) poorly developed marketing channels and infrastructure, and limited involvement of the private sector in the distribution of inoculants, and (5) limited farmer awareness about and access to (much more than price) inoculants. The lessons learned include the need: (1) to increase investment in Rhizobium inoculation technology development, and strengthen policy and institutional support, (2) for public private partnership in the development, deployment and dissemination of BNF technologies, (3) to develop effective BNF dissemination strategies (including participatory approach) to reach farmers, (4) for greater emphasis on capacity building along the BNF value chain, and (5) for partnership between universities in SSA and those in the North on BNF research. Keywordslow soil fertility–N2 fixation–inoculants–soybean–adoption drivers–sub-Saharan Africa
 
Article
Land degradation, rising population and poverty in sub-Saharan Africa threatens the agricultural sustainability and productivity, quality of the environment and socio-economic wellbeing of rural populations. We studied farm ecological, economic and social sustainability, productivity and production risks in the Mbeere District of Eastern Kenya. We used a soil nutrient monitoring methodology to collect data from 30 households. Ecological sustainability was threatened by soil nutrient decline at rates of 1.7 kg P and 5.4 kg K ha−1 half year−1 while N was nearly balanced in soils. Soil phosphorus and potassium stocks, in the cultivated soils, declined at rates of 0.3% and 0.1% half year−1, respectively. Farm economic returns were positive, albeit low, and could not sustain the livelihoods of the households. All the 30 households were living below the poverty line of 1 US dollar a day. Farm productivity was low, with livestock and yields of major staple food crops below on-farm target yields. To spread out the risks of production, farming households were cultivating an average of 4.7 crop fields, keeping more than two types of livestock and practising intercropping systems. Intercropping maize-beans reduced nutrient decline and raised household incomes compared with monocropping of either of the two crops. Despite the low rates of nutrient decline, high risks of production and the low crop yields, the livestock productivity and farm economic performance put the sustainability of these farming systems into question. The low levels of nutrient decline in small farms averaging at 1.7 kg P and 5.4 kg K ha−1 half year−1 contrasts with the high nutrient depletion rates on macro-scale levels, e.g. 20–40 N, 3.5–6.6 kg P and 20–40 kg K ha−1 year−1 for Eastern African countries and 22 kg N, 2.5 kg P and 15 kg K ha−1 year−1 for sub-Saharan Africa. These findings indicate that the extent of nutrient decline and conservation differs across sub-Saharan Africa. The positive contribution of intercropping to nutrient balances suggests the need to encourage farmers to adopt such systems rather than monocropping. agro-ecological sustainability–drylands–production risks–socio-economic sustainability–sustainable agriculture
 
A comparison of soil organic C on adjacent matched farms, one without Amenagement en courbes de niveau (ACN) and one with ACN, Siguidolo, Mali. Soil C was significantly higher with the ACN technology. Treatments differed at the P = 0.076 level.  
The change in soil organic C with time under Aménagement en courbes de niveau, (ACN) Siguidolo, Mali. Prediction equation: Soil organic C, g kg −1 = 1.987 × 0.226 × Years, Adj R 2 = 0.41. The regression was significant at P = 0.035. The results indicate a continual increase of soil organic C with longer time under the ACN soil and water conservation practice.  
The change in soil organic C, Senegal Peanut Basin, 2004– 2006. Mean of 7 farm experiments. Soil organic C in the Amenagement en courbes de niveau (ACN) plots was higher than in plots without ACN (no-ACN) at Prob. (<0.01). The ACN technology was adapted for planting on the flat rather than on ridges as in Mali and soil organic C increased as well.  
The Amenagement en courbes de niveau (ACN) experimental sites: Yundum, The Gambia; Nioro, Senegal, Siguidolo and Sougoumba, Mali.  
Article
A recent Intergovernmental Panel on Climate Change (IPPC) report concludes that global warming, while already a global crisis, is likely to become even more devastating. The scientific consensus is that global warming is caused by increases in greenhouse gases including carbon dioxide. The Sahel of West Africa seems to be more adversely affected by such climate changes, leading to reduced and more sporadic rainfall. In addition, food security in the region is tenuous and fragile, due to adverse climate change, but also due to the historical mining of nutrients and carbon. With the adoption of the Kyoto accords, at least by some countries, sequestered carbon (C) has become a tradable commodity. This provides a double incentive to increase soil organic carbon in the C-depleted and degraded soils of West Africa — return C to improve soil quality and assist in removing CO2 from the atmosphere to assist in mitigating climate change. A challenge, however, remains to determine which agricultural systems can actually sequester C. The technology called Aménagement en courbes de niveau (ACN), which can be roughly translated as ‘Ridge-tillage’, has given crop yield increases of 30 to 50%. To date, there has only been anecdotal evidence suggesting that Aménagement en courbes de niveau leads to increased soil organic C. The objectives of the study reported here were to determine whether the technology has the potential to sequester C in West African soils, and, if so, how much. In this study, soil organic C was measured by combustion methods in soils sampled at 0–20 and 20–40 cm depths in a series of experiments in Mali, Senegal and The Gambia. Soil organic C was measured in three very different types of experiments, all including Aménagement en courbes de niveau technology, resulting in three methods of measuring C sequestration. Our results indicate that the Aménagement en courbes de niveau technology significantly increased maize yields by 24% by weight in the Gambia experiment while soil organic C was increased by 26% in The Gambia, by 12% in Siguidolo, Mali, and by 14% in peanut systems of Nioro, Senegal. These increases in soil organic C are likely due to three factors: (1) reduced erosion and movement of soil, (2) increased crop growth resulting from the greater capture of rainfall, and (3) increased growth and density of shrubs and trees resulting from the increased subsoil water, resulting in turn from the increased capture of rainfall, and reduced runoff. Measuring soil C on fields that were successively placed under Aménagement en courbes de niveau management and the use of replicated experimental plots appear to be the best methods to quantify the C sequestration potential of the practice. These results indicate that this soil and water conservation technology not only harvests water and increases food production, but also increases soil organic carbon. This technology thus is a successful technique to sequester C in soils and if carried out in a large region may both offset CO2 emissions and help mitigate climate change. ACN– Aménagement en courbes de niveau –ridge-tillage–Mali–Senegal–The Gambia–soil organic carbon–reductions in carbon dioxide–carbon sequestration–climate change
 
Comparison of food production between irrigated and rainfed agriculture in the world and Iran (Source: Ehsani, 2005, p. 4).
Trends in fertilizer consumption changes during the Water Exploitation Era in Iran (Source: FAO, 2005).
The trend of agricultural water sustainability in Iran.
Article
Water resources are declining at an alarming rate in the world. The use of water resources for agricultural production has contributed to the rapid decline in quantity and degradation of water quality. Though sustainable agriculture must be economically viable, ecologically sound and socially responsible, water scarcity has challenged the sustainability of agriculture, especially in arid and semi-arid regions. There is a relative consensus among professionals that the increasing water scarcity through excessive use of water and mismanagement of the available water resources are major concerns for agricultural sustainability. Agricultural sustainability is assessed using various indicators, but the contribution of the water factor in those indicators is limited. Therefore, we review the role of sustainable water management in achieving agricultural sustainability. We propose an agricultural water poverty index (AWPI) as an instrument to provide a holistic picture of vital issues for sustainable water management. We also distill key components of the agricultural water poverty index and discuss its applications. The agricultural water poverty index can be used to assess the agricultural water poverty among farmers and regions and to provide guidelines for sustainable water management. This article uses the case of Iran to illustrate the application of the agricultural water poverty index in analyzing agricultural water poverty and providing recommendations for sustainable water management. Keywordssustainable agriculture–water management sustainability–agricultural water poverty–Iran
 
The TransForum network: knowledge institutes, governmental authorities, civil society organisations (including consumer organisations) and the private sector (including farmers). This network is referred to as KOMBI ( = Dutch acronym) partners. TransForum is acting as an intermediary in the network. 
Illustration of how TransForum's three innovation strategies fit with the ideas presented in "The Information Age: Economy, Society and Culture" (Castells, 1996, 1997). Regional development represents new combinations of activities for rural areas, representing the 'space of places' of Castells (1997). International agro-food networks represent new trans-frontier production and trade networks in which the Dutch agro sector can have its own specific niche, representing the 'space of flows'. Vital clusters are new combinations of economic sector in spatially concentrated clusters, were the 'space of places' and the 'space of flows' meet each other.
TransForum’s scientific program is organised in four themes following a cyclic innovation process which is constantly monitored. The cycle starts with 1: people’s preferences and images, followed by 2: studies on which inventions are required to achieve a successful innovation. Subsequently, 3: it is investigated how to organize new innovations and transitions and finally, 4: how citizen / consumers behaviour and preferences mobilizes sustainable development, closing the loop. The box represents the fifth theme on self reflection providing the means to evaluate the e ff ectiveness and e ffi ciency of the learning system. 
Chapter
TransForum is an innovation program which aims to make a substantial contribution to the transition towards more sustainable development of the Dutch agricultural sector. This article describes the scientific foundation and architecture of this program. TransForum operates on the basis of five working hypotheses which together constitute one integrated analytical framework. These hypotheses are: (1) sustainable development is a dynamic system property; (2) sustainable development needs system innovation; (3) system innovation is a non-linear learning process; (4) system innovation requires active participation of relevant key players from knowledge institutes, governmental bodies, civil society organisations and the business community; (5) the program requires transdisciplinary collaboration of all players. TransForum identifies three new innovation strategies: (1) vital clusters; (2) regional development; (3) international agro-food networks; as alternatives to the current arrangements. Innovative projects are organised in these innovation strategies. The aim of the scientific program is threefold: (1) it addresses research questions raised in the innovative projects; (2) it investigates the need for system-innovations and the way in which they can be realized; (3) it designs research projects to test the five main working hypotheses of the program. The scientific program is organised in four themes following a cyclic innovation process which is constantly monitored. The cycle starts with people’s preferences and images, followed by studies on which inventions are required to achieve a successful innovation. Subsequently, it is investigated how to organize new innovations and transitions and finally, how citizen/consumers behaviour and preferences mobilizes sustainable development, closing the loop. KeywordsNetworks–Sustainable development–System innovation – Transition
 
Article
The food security challenges faced by populations in sub-Saharan Africa and the fact that extensive production systems are reaching their limits in the food-producing agricultural chain have increased the need to accelerate technological innovation toward the ecological intensification of agricultural production systems. Here, a review of the research conducted on plantain bananas (Musa paradisiaca) in Cameroon since 1988 revealed how institutional innovation has enabled the hybridization of different research forms—such as fundamental, systems, and action research—and reinforced the organizational innovation required for technical change. We found that impact evaluation underlined the complementarity between the increases in productivity and income in rural areas, as well as the production of human and social capital and the protection of forest resources. KeywordsInnovation–Agricultural technology–Institutional–Information–Knowledge
 
Beneficial management practices (BMP) related to N fertilizer management, recommended for the province of Manitoba to reduce the GHG emission and increase the environmental stewardship (modified after Eco-ressources Consultants 2009)
Summary-effect of nitrogen fertilizer on N 2 O emission
Beneficial management practices (BMP) related to livestock management, recommended for the province of Manitoba to reduce the GHG emission and increase the environmental stewardship (modified after Eco-ressources Consultants 2009) 
Summary—effect of various agricultural activities on greenhouse gas emissions 
Beneficial management practices (BMP) related to cropping systems, recommended for the province of Manitoba to reduce the GHG emission and increase the environmental stewardship (modified after Eco-ressources Consultants 2009) 
Article
Climate change is one of the main global issues of modern time. Ever increasing demand for food/feed and the need for higher environmental standards require shaping of the agricultural activities toward ecological and more sustainable efficient systems. One of the principal ways of attaining higher productivity and environmental standards is identification and adoption of beneficial management practices (BMP) by reviewing the conventional agricultural activities. The BMP are agricultural practices that promote sustainable land stewardship and maintain/increase profitability of farms. The BMP are from both crop and animal production systems and tradeoffs between the two systems could provide several opportunities in reducing, removing and/or avoiding of greenhouse gases (GHG) emissions. Despite that, few reviews have presented them together. This review covers GHG emissions related to the BMP in the crop and animal production systems of farms relevant to Canadian Prairie. These BMP include: (1) use of inorganic N fertilizers, (2) livestock and feed management, (3) manure management, (4) cropping systems, (5) tillage practices and (6) improved pasture and grazing management. In addition, sources of variations, quantification methods and adoptability are discussed. Quantified GHG emissions from direct and indirect measurements of researches from Canada and other part of the world are included. Since most experiments are conducted under multiple biophysical scenarios while adopting various methodologies, summarizing the findings was difficult. The effect of BMP on GHG is determined by ecological processes. Such determinants are discussed and knowledge gaps are identified. Integration of crop and livestock production systems could further lead toward higher energy and resource use efficiency; hence less GHG emissions. KeywordsBMP–Canadian Prairie–Cropping systems–GHG–Livestock–Pasture
 
Article
Despite the liberal use of broad-spectrum insecticides to keep many insect pests of agricultural and veterinary importance at bay, food losses, both pre- and post-harvest, due to these insect pests contribute significantly to the high prevalence of undernourishment in the world. New, innovative pest control tactics and strategies are therefore needed that are both effective and not detrimental to the environment. As part of the arsenal of environmentally-friendly control tactics, the sterile insect technique (SIT) has proven to be a very effective tool against selected insect pests when used as part of an area-wide integrated pest management (AW-IPM) approach. Likewise, the use of natural enemies for augmentative or inundative biological control is now a major component of pest control in many parts of the world. Both control tactics are complementary and even synergistic under certain circumstances, but their combined use has so far not been applied on an operational scale. Ionising radiation can be readily employed to effectively and safely induce sexual sterility in insects. Although the sterile insect technique has often been associated with an eradication strategy, major advances in rearing efficiency, and improved handling and release methods, have made the use of sterile insects economically feasible for insect pest suppression, prevention or containment. Recently, more emphasis has been placed on the quality of the sterile insect once released in the field rather than mainly assessing quality in the rearing facility. This combined with other innovations such as the development of genetic sexing strains, better understanding the impact of radiation on radio-resistant species such as Lepidoptera and the development of the F1 sterility concept, advances in monitoring the induced sterility, etc. have significantly increased the efficiency of the sterile insect technique for several insect species. The action of sterile insects is inversely dependent on the density of the target population, and sterile insects have the intrinsic capacity to actively search for and mate with the last individuals of a pest population. These two characteristics make them ideal to deal with outbreaks of invasive insect pests. The use of sterile insects presents no threat to the environment, but aspects such as diet and waste disposal in large rearing facilities or bio-security in cases where the rearing facility is located in an area that is already free of the pest require the necessary attention. Ionising radiation can also be applied to greatly improve the efficiency of mass-rearing, handling and shipment of insect parasitoids and predators. Area-wide integrated pest management programmes that use sterile insects or natural enemies are complex and management-intensive, and require a management structure that is exclusively dedicated to the programme. Past and current examples have shown the enormous benefit-cost ratios that these programmes can generate and their importance for enhanced agriculture is increasing in significance. Keywordsnatural enemies–sterile insect technique–area-wide integrated pest management–economic benefits
 
Average biomass yield of aromatic and medicinal plant strips for the four-year monitoring period.  
Average nut yield from almond trees for the four-year monitoring period. Vertical bars represent standard deviation.  
Cumulative nut and essential oil yield for each soilmanagement system for the four-year monitoring period.  
Article
Erosion degrades soil quality in agricultural ecosystems, thereby reducing the productivity of the land. Semi-natural vegetation and diverse cropping systems have been converted into monocultures with low tree densities, leaving the soil unprotected. We evaluated the association in soil- and water-conservation systems with production in traditional almond orchards and the beneficial impact of plant strips in mountainous agriculture. Soil loss, runoff and nutrient loss over a four-year period (2002–2005) were monitored in hillside erosion plots with almond trees under different soil-management systems: (1) non-tillage with sage (Salvia lavandulifolia L. subspecies Oxyodon) strips 3 m wide; (2) non-tillage with rosemary (Rosmarinus officinalis L.) strips, (3) non-tillage with thyme (Thymus baeticus L. Boiss. exlacaita) strips, and (4) conventional tillage on the south flank of the Sierra Nevada (Lanjaron) in south-eastern Spain. Also, the nut yield from almond trees, and the biomass from aromatic-shrub strips were measured. The erosion plots, located on a 35% slope, were 144 m2 in area. The plant-cover strips, 3 m wide, ran across the slope. Our results show that the most effective treatment proved to be non-tillage with thyme strips, reducing the annual soil loss by 93% and runoff by 80%, with respect to conventional tillage. Non-tillage with rosemary strips reduced soil loss by 91 % and runoff by 82%, with respect to conventional tillage, while these percentages were 69% and 51%, respectively, for non-tillage with sage strips. In addition, all the treatments as a whole, in comparison with conventional tillage, revealed that the plant strips were the decisive factor in the reduction of NPK losses by surface runoff. The average nut yield from non-tillage with sage strips, non-tillage with rosemary strips, non-tillage with thyme strips and conventional tillage during the study period was 2.4, 3.2, 3.8 and 4.5 kg tree−1, respectively, and the essential oil yield from sage, rosemary and thyme strips was 5.0, 8.7 and 10.8 L ha−1, respectively. The non-tillage with thyme strips decreased nutrient loading in surface waters and thus had a positive impact on the environment while simultaneously maintaining reasonable almond-production levels. Thus, the combination of orchard trees with shrubs provided a viable option to conserve soil and water in hilly areas with opportunities to increase overall land productivity as well as sustainable agro-environmental measures. almond orchards–aromatic-shrub-cover strips–biomass production–hillslope erosion–mountainous agriculture–soil-management systems
 
Plots of linkage disequilibrium as measured with the commonly used statistic (r 2 ) (y axis), which is based on the allele frequencies at two loci as a function of distance in kilobases (kb) (x axis) for the (A) cultivated, (B) landrace, and (C) wild samples (Caldwell et al., 2006).
Barley chromosome 'bin' map showing the location of phenotypes associated with yield under drought stressed environment conditions.
Protein yields of modern varieties and breeding lines, varieties bred for organic farming and landraces or very old varieties in an environment with high and low average protein yield, respectively. The latter group have relatively high protein yields in the lowyielding environments, but low performance in the high-yielding environments. Results of a linear regression analysis on 70 genotypes in 9 environments; see Baresel et al. (2005) for details.
Chapter
Modern agriculture and conventional breeding and the liberal use of high inputs has resulted in the loss of genetic diversity and the stagnation of yields in cereals in less favourable areas. Increasingly landraces are being replaced by modern cultivars which are less resilient to pests, diseases and abiotic stresses and thereby losing a valuable source of germplasm for meeting the future needs of sustainable agriculture in the context of climate change. Where landraces persist there is concern that their potential is not fully realised. Much effort has gone into collecting, organising, studying and analysing landraces recently and we review the current status and potential for their improved deployment and exploitation, and incorporation of their positive qualities into new cultivars or populations for more sustainable agricultural production. Inparticular their potential as sources of novel disease and abiotic stress resistance genes or combination of genes if deployed appropriately, of phytonutrients accompanied with optimal micronutrient concentrations which can help alleviate aging-related and chronic diseases, and of nutrient use efficiency traits. We discuss the place of landraces in the origin of modern cereal crops and breeding of elite cereal cultivars, the importance of on-farm and ex situ diversity conservation; how modern genotyping approaches can help both conservation and exploitation; the importance of different phenotyping approaches; and whether legal issues associated with landrace marketing and utilisation need addressing. In this review of the current status and prospects for landraces of cereals in the context of sustainable agriculture, the major points are the following: (1) Landraces have very rich and complex ancestry representing variation in response to many diverse stresses and are vast resources for the development of future crops deriving many sustainable traits from their heritage. (2) There are many germplasm collections of landraces of the major cereals worldwide exhibiting much variation in valuable morphological, agronomic and biochemical traits. The germplasm has been characterised to variable degrees and in many different ways including molecular markers which can assist selection. (3) Much of this germplasm is being maintained both in long-term storage and on farm where it continues to evolve, both of which have their merits and problems. There is much concern about loss of variation, identification, description and accessibility of accessions despite international strategies for addressing these issues. (4) Developments in genotyping technologies are making the variation available in landraces ever more accessible. However, high quality, extensive and detailed, relevant and appropriate phenotyping needs to be associated with the genotyping to enable it to be exploited successfully. We also need to understand the complexity of the genetics of these desirable traits in order to develop new germplasm. (5)Nutrient use efficiency is a very important criterion for sustainability. Landrace material offers a potential source for crop improvement although these traits are highly interactive with their environment, particularly developmental stage, soil conditions and other organisms affecting roots and their environment. (6) Landraces are also a potential source of traits for improved nutrition of cereal crops, particularly antioxidants, phenolics in general, carotenoids and tocol in particular. They also have the potential to improve mineral content, particularly iron and zinc, if these traits can be successfully transferred to improved varieties. (7) Landraces have been shown to be valuable sources of resistance to pathogens and there is more to be gained from such sources. There is also potential, largely unrealised, for disease tolerance and resistance or tolerance of pest and various abiotic stresses too including to toxic environments. (8) Single gene traits are generally easily transferred from landrace germplasm to modern cultivars, but most of the desirable traits characteristic of landraces are complex and difficult to express in different genetic backgrounds. Maintaining these characteristics in heterogeneous landraces is also problematic. Breeding, selection and deployment methods appropriate to these objectives should be used rather than those used for high input intensive agriculture plant breeding. (9) Participatory plant breeding and variety selection has proven more successful than the approach used in high input breeding programmes for landrace improvement in stress-prone environments where sustainable approaches are a high priority. Despite being more complex to carry out, it not only delivers improved germplasm, but also aids uptake and communication between farmers, researchers and advisors for the benefit of all. (10) Previous seed trade legislation was designed primarily to protect trade and return royalty income to modern plant breeders with expensive programmes to fund. As the desirability of using landraces becomes more apparent to achieve greater sustainability, legislation changes are being made to facilitate this trade too. However, more changes are needed to promote the exploitation of diversity in landraces and encourage their use. KeywordsDiversity-Disease-Yield-Quality-Nutrition-Breeding-Genotyping-Competition-Cultivar degeneration-Whole-plant field phenotyping-Non-stop selection-Adaptive variation
 
Chapter
Indigenous tillage systems are often undervalued in conservation agriculture (CA). In Ethiopia, since the 1970s there have been several attempts to develop and implement often major modifications to the marasha, the traditional ox-drawn ard plough, with the main aim of creating various types of surface depressions. The establishment of furrows and ridges increases soil moisture and grain yield and reduces soil loss. Dissemination of the modified tools, however, remains limited. Recent tendencies are towards testing relatively simple conservation agriculture tools. Major challenges remain, however; the need for capacity building and problems in marketing the tools. From experimental plots, often worked with exotic tools, there is a long road to real adoption by farmers. Rather than developing yet another CA tool, we investigate whether CA-based resource-conserving technologies might be achieved successfully with simple changes to the use of the marasha. On-farm observations on traditional conservation techniques were carried out throughout the northern Ethiopian highlands, and experiments were conducted involving resource-conserving technologies. Farmers traditionally use the marasha ard plough for various types of insitu soil and water conservation by creating surface depressions, either at the moment of sowing (terwah, derdero) or after crop emergence (shilshalo). Building upon this indigenous knowledge, we further developed resource-conserving technologies into a system named derdero+, whereby the traditional ard plough was found suitable for a “bed-and-furrow” system. From the socio-economic point of view, implementation of permanent beds and retention of stubble leads to decreased oxen (and straw) requirements, but also toan increased need for weeding in the first years. To overcome that problem, we introduced glyphosate herbicide into the tillage system. The decreased runoff ( − 51%) and soil loss ( − 81%) allow protection of the downslope areas from flooding, but soil nutrient build-up and soil structure improvement are slow processes, and hence the full benefit of the permanent bed system can only be expected after some years. Overall, this type of resource-conserving technology can be part of the ongoing intensification process which includes physical soil and water conservation, slope reforestation and irrigation development. It has, however, its own niche: the cropped land sensu stricto, i.e. the most important part of the land, both for the farmer and for a nation that is striving for long-term food security. KeywordsAnimal traction-Ard plough-Conservation tillage-Conservation agriculture- Derdero+ - Marasha -Indigenous knowledge-Permanent beds-Raised beds-Resource-conserving technology-Soil and water conservation
 
Distribution of the sampled swards (above) and the species (below) in the space generated by the two first canonical correspondence analysis axes. Above: only mown (squares); sheep-grazed (open dots); cattle-grazed (filled dots). Below: species contributing more than 15% to fit are represented with small dots. The management treatments are represented in the same space. Arrows indicate the direction of change for quantitative variables (year after sowing and interactions). Triangles indicate the position of the categories for the qualitative variables (management treatment and sainfoin monoculture/mixture with dactyl). The distribution of samples and species shows strong shifts in vegetation composition with management that increase with time
Variables included in a canonical correspondence analysis related to changes in species composition in sainfoin swards 
Change in total aboveground biomass with unsown species proportion for the three sward managements. Dots represent actual data. Lines are drawn from predicted values obtained from the model in Table 6. Sheep grazing (open dots and dotted line); cattle grazing (filled dots and solid line); only mown (open squares and dashed line). Management tested against sheep grazing. Total aboveground biomass decreased with unsown species depending on management and diversity variables  
Confidence intervals (95%) for the Bray–Curtis vegetation similarity index calculated within and between treatments 
Article
Management affects ecosystem structure in many ways. Structural changes in ecosystems, including shifts in vegetation composition and species diversity, will affect the goods and services provided at ecosystem and regional scales. This is relevant for agricultural production and agro-biodiversity preservation in the context of management changes currently occurring in many regions. We sampled 39 sainfoin swards in the Eastern Pyrenees to assess changes in vegetation structure with sward management and evaluated how those changes might sustain agro-diversity regionally. Three sward managements coexist in the region: (a) mown plus sheep-grazed, (b) mown plus cattle-grazed and (c) only mown. Plant species composition and richness, and various biomass variables were estimated at peak biomass on swards with the three managements and different ages. We used a synchronic approach to study time effects, in which swards of different ages are sampled simultaneously, in a space by time substitution. Multivariate analysis and similarity indices revealed strong shifts in vegetation composition with management, enhanced with sward age, when the suppressive effect of sown on unsown plants relaxed. Generally, plant species richness increased with time. Old mown swards showed the highest number of species per plot (34 in 4m2). Cattle-grazed swards showed the highest within- and between-treatment vegetation dissimilarity with time. Biomass variables responded mainly to time effects, but total aboveground biomass decreased with unsown species and increased with species richness depending on management. Thus, the diversity of managements modified the expected outcome in local and regional agro-diversity and sward structure. Our results are novel because they demonstrate strong effects of grazing by different animals on local and regional agro-diversity and herbage composition in those ephemeral legume-based forage systems. Farmers and managers should take into account those shifts in order to achieve agricultural goals, including agro-diversity conservation and sustainable forage production at ecosystem and regional scales. KeywordsAgroecosystem–Community assembly–Grazing–Mowing– Onobrychis viciifolia –Plant species diversity
 
Article
Since 2005, French farmers must set up sown grass strips along rivers in order to decrease pesticide levels and soil erosion. Farmers have thus parcelled out their fields, set aside 3% of their farm size and managed grass without herbicide. Consequently, this environmental policy may cause farmers’ fears due to economic losses and weed infestations of their field margins. Here, we studied farmers’ perception of sown grass strips. First, we interviewed 29 farmers in two French regions. Second, we evaluated the economic loss of gross margin when replacing crop by grass. Third, we evaluated the weed risk using flora surveys in sown grass strips. Our results showed that two thirds of interviewed farmers thought that sown grass strips affected their farm revenue and represented a weed risk. Concerning economy, we found that farmers loose from 358 to 853€/ha the year of installation and from 126 to 641€/ha next years. This economic loss is mainly due to the loss of crop production, with a minor impact of grass management cost. At the farm level, 3% of sown grass strips decreased the farm revenue by 7%. Concerning the weed risk, the farmers’ perception was linked with the presence of some competitive perennial weeds, e.g. Cirsium arvense, and wind-dispersing weeds, e.g. Asteraceae. Sown grass strips with high weed species richness of 26 species on average, or with dominance of non-sown species (16.7% of sown grass strips) did not affect the farmers’ perception. In our study, the economic loss was weak and acceptable at the farm level. KeywordsField margin–Weed risk–Gross margin–Agri-environmental measure–Farmers’ acceptance
 
Article
Comparative functional ecology seeks to understand why and how ecological systems and their components operate differently across environments. Although traditionally used in (semi)-natural situations, its concepts and methods could certainly apply to address key issues in the large variety of agricultural systems encountered across the world. In this review, we present major advances in comparative plant functional ecology that were made possible over the last two decades by the rapid development of a trait-based approach to plant functioning and prospects to apply it in agricultural situations. The strength of this approach is that it enables us to assess the interactions between organisms and their environment simultaneously on a large number of species, a prerequisite to address questions relative to species distribution, community assembly and ecosystem functioning. The trait concept will be first defined, before presenting a conceptual framework to understand the effects of environmental factors on plant community structure and ecosystem properties via plant traits. We will then argue that leading dimensions of variation among species can be captured by some selected traits and show that a combination of three easily measured traits—specific leaf area (the ratio of leaf area to leaf dry mass), plant height and seed mass—enables us to assess how different species use their resources, interact with neighbours and disperse in time and space. The use of traits to address central questions in community ecology will be reviewed next. It will be shown that traits allow us to (1) understand how plant species are sorted according to the nature of environmental gradients, (2) evaluate the relative importance of habitat filtering and limiting similarity in the process of community assembly and (3) quantify two main components of community functional structure, namely, community-weighted means of traits and community functional divergence. The relative impacts of these two components on ecosystem properties will then be discussed in the case of several components of primary productivity, litter decomposition, soil water content and carbon sequestration. There is strong support for the biomass ratio hypothesis, which states that the extent to which the traits of a species affect those ecosystem properties depends on the abundance of this species in the community. Assessing the role of functional divergence among species on ecosystem properties will require major methodological breakthroughs, both in terms of metrics and statistical procedures to be used. In agricultural situations, we show that trait-based approaches have been successfully developed to assess the impacts of management practices on (1) the agronomic value of grasslands and (2) the functional composition and structure of crop weed communities and how these could affect the functioning of the crop. Applications in forestry are still poorly developed, especially in temperate regions where the number of species in managed forest remains relatively low. The last decades of research have led to the constitution of large data sets of plant traits, which remain poorly compatible and accessible. Recent advances in the field of ecoinformatics suggest that major progress could be achieved in this area by using improved metadata standards and advancing trait domain ontologies. Finally, concluding remarks, unanswered questions and directions for research using the functional approach to biodiversity made possible by the use of traits will be discussed in the contexts of ecological and agronomical systems. The latter indeed cover a wide range of environmental conditions and biological diversity, and the prospect for reducing environmental impacts in highly productive, low-diversity systems will certainly imply improving our skills for the management of more diverse systems prone to a trait-based approach as reviewed here. KeywordsAgroecology–Biodiversity–Community structure–Comparative ecology–Ecoinformatics–Ecological strategy–Ecosystem properties–Environmental conditions–Functional diversity–Plant functional trait
 
Summary of changes to single practices for preventing the spatial and temporal synchronisation of the crop and pests  
Article
Increasing the use of synthetic fertilisers and pesticides in agroecosystems has led to higher crop yields, accompanied by a decline in biodiversity at the levels of field, cropping system and farm. Biodiversity decline has been favoured by changes at landscape level such as regional farm specialisation, increases in field size, and the removal of hedgerows and woodlots. The loss of biodiversity in agroecosystems has increased the need for external inputs because beneficial functions are no longer provided by beneficial species as natural enemies of crop pests and ecosystem engineers. This trend has led to a strong reliance on petrochemicals in agroecosystems. However, many scientists have been arguing for more than two decades that this reliance on petrochemicals could be considerably reduced by a better use of biotic interactions. This article reviews options to increase beneficial biotic interactions in agroecosystems and to improve pest management and crop nutrition whilst decreasing petrochemical use. Four agronomic options are presented. First, it has been shown that the choice of cultivar, the sowing date and nitrogen fertilisation practices can be manipulated to prevent interactions between pests and crop, in either time or space. Nevertheless, the efficacy of these manipulations may be limited by pest adaptation. Second, beneficial biotic interactions may result from appropriate changes to the habitats of natural enemies and ecosystem engineers, mediated by soil and weed management. Here, knowledge is scarce, and indirect and complex effects are poorly understood. Third, changes achieved by crop diversification and, fourth, by landscape adaptation are promising. However, these practices also present drawbacks that may not necessarily be outweighed by beneficial effects. Overall, these four management approaches provide a powerful framework to develop sustainable agronomic practices.
 
Article
Farmers are facing serious plant protection issues and phytosanitary risks, in particular in the tropics. Such issues are food insecurity, lower income in traditional low-input agroecosystems, adverse effects of pesticide use on human health and on the environment in intensive systems and export restrictions due to strict regulations on quarantine pests and limits on pesticide residues. To provide more and better food to populations in both the southern and northern hemispheres in a sustainable manner, there is a need for a drastic reduction in pesticide use while keeping crop pest and disease damage under control. This can be achieved by breaking with industrial agriculture and using an agroecological approach, whose main pillar is the conservation or introduction of plant diversity in agroecosystems. Earlier literature suggest that increasing vegetational biodiversity in agroecosystems can reduce the impact of pests and diseases by the following mechanisms: (1) resource dilution and stimulo-deterrent diversion, (2) disruption of the spatial cycle, (3) disruption of the temporal cycle, (4) allelopathy effects, (5) general and specific soil suppressiveness, (6) crop physiological resistance, (7) conservation of natural enemies and facilitation of their action against aerial pests and (8) direct and indirect architectural/physical effects. Here we review the reported examples of such effects on a broad range of pathogens and pests, e.g. insects, mites, myriapods, nematodes, parasitic weeds, fungi, bacteria and viruses across different cropping systems. Our review confirms that it is not necessarily true that vegetational diversification reduces the incidence of pests and diseases. The ability of some pests and pathogens to use a wide range of plants as alternative hosts/reservoirs is the main limitation to the suppressive role of this strategy, but all other pathways identified for the control of pests and disease based on plant species diversity (PSD) also have certain limitations. Improving our understanding of the mechanisms involved should enable us to explain how, where and when exceptions to the above principle are likely to occur, with a view to developing sustainable agroecosystems based on enhanced ecological processes of pest and disease control by optimized vegetational diversification. KeywordsIntegrated pest management–Agroecology–Conservation agriculture–Horticulture–Agroforestry
 
Versatile multi-crop planter (VMP), with seed and fertilizer delivery attachments fitted to a Chinese-made two-wheel tractor (power tiller), sowing lentil by strip tillage after rice, Bangladesh, November 2009. The machine can be easily modified to sow by zero tillage (all rotary blades removed), full tillage (all rotary blades present), and to sow on beds 
of IPM on the incidence of larvae, percentage of bored pods and on grain yield of a sole crop of chickpea in the High Barind Tract of Bangladesh, 2004-2005
Article
Although there is increasing awareness of the importance of food legumes in human, animal and soil health, adoption of improved production technologies for food legume crops is not proceeding at the same pace as for cereal crops. Over the previous decade, the only food legumes to have shown significant production increases have been chickpea, lentil and faba bean in North America, chickpea in Australia, and faba bean in Europe. In smallholder farming in developing countries, production trends have mostly been static or have declined over the past decade despite the existence of technology that should permit higher and more stable yields. Ability to reverse negative trends is jeopardized by climate change as food legumes are mostly grown rainfed and are being exposed to increasingly variable and extreme weather. This review examines recent innovations in cultivation technology for the major food legumes—chickpea, lentil, dry pea, faba bean, lupin, common bean, mung bean, black gram, cowpea, and pigeonpea—and explores constraints to their adoption, particularly by resource-poor smallholder farmers. Conservation agriculture, involving minimum soil disturbance, maximum soil cover, and diverse rotations, has contributed to sustainable cropping system production in large-scale commercial farming systems in the Americas, Europe, Australia, and Turkey. Temperate food legumes have been incorporated into such systems. Adoption of conservation agriculture is only just beginning for smallholder farming in Asia and Africa, catalyzed by the development of low-cost implements suitable for minimum tillage. Water use efficiency improves with conservation agriculture as it allows for earlier planting, reduced soil evaporation, better weed management, and increased access to nutrients. Ecosystem-based approaches to plant nutrition are evolving which place more reliance on accessing organic and mineral reservoirs than in replenishing the immediately available pool with chemical fertilizers, leading to enhanced nutrient use efficiency of cropping systems. Ecosystem-based approaches are also being applied to management of weeds, diseases, and insect pests of food legumes, again with decreased reliance on synthetic chemicals. In achieving sustainable agricultural production systems, there is increasing realization of the need to move towards the tenets of organic agriculture, as exemplified in conservation agriculture and ecosystem-based approaches to plant nutrition and pest management. This does not necessarily imply a desire to qualify for organic product certification but more a realization of the need for sustainable agriculture. The movement towards conservation and organic agriculture encourages greater inclusion of food legumes, and legumes generally, in cropping systems. Unfortunately, however, technology transfer to resource-poor farming situations, where most food legumes are produced, remains a major bottleneck to meeting global demand. More participatory approaches to technology development, testing, and dissemination are required than hitherto practiced. It is suggested that this process could be enhanced by better focusing on major constraints within the value addition chain for food legumes. KeywordsLegume area trends–Climate change–Conservation agriculture–Smallholder farming–Water use efficiency–Nutrient use efficiency–Weeds–Integrated disease management–Integrated crop management
 
Article
In conventional agriculture, weed control by herbicides is an expensive practice and can also have a negative effect on the environment. Allelopathy permits sustainable weed management while reducing the impact of agriculture on the environment. We studied the content of 2,4-dihydroxy-1,4 (2H)-benzoxazin-3-one (DIBOA) and benzoxazolin-2(3H)-one (BOA), indicated as benzoxazinoids and considered effective for weed control, in 8 cultivars of rye and 1 of triticale grown in a greenhouse. We also tested the ability of mulches to inhibit the germination of four warm-season weeds. Our results show that all rye cultivars produced DIBOA, while BOA was found only in four of them. Benzoxazinoids were absent in triticale. Total benzoxazinoid content ranged from 177 to 545 μg g−1 and was statistically different among cultivars. Rye mulches were not able to suppress velvetleaf and common lambsquarters seedlings, while redroot pigweed and common purslane were significantly affected. Weed suppression ranged from 40% to 52% for redroot pigweed and from 40% to 74% for common purslane. The inhibitory activity of triticale mulch was observed only for common purslane, with a suppression percentage of 33%. No correlation was found between total benzoxazinoid content and the number of weed seedlings suppressed, with R2 of 0.076 for redroot pigweed and R2 of 0.003 for common purslane, indicating that benzoxazinoids are not the only source of phytotoxicity. allelopathy–BOA–DIBOA–integrated weed control–mulch–rye–triticale
 
Soil N mineral deficit as a mean of the two-year experiment for conventional soil tillage as affected by N treatments. Within each determination, the histograms with the same letters are not significantly different at P ≤ 0.05, according to Duncan's Multiple Range Test. Histograms without letters indicate no significant difference among means. (1) Mineral = mineral fertiliser at 100 kg N ha −1 ; Organic = municipal solid waste at 100 kg N ha −1 ; Mixed = 50 kg N ha −1 of municipal solid waste and 50 kg N ha −1 of mineral fertiliser; Slow-release = 100 kg N ha −1 of slow-release organic-mineral N fertiliser; Reduced = mineral fertiliser at 50 kg N ha −1 ; Control = unfertilised treatment.
Chemical characteristics of the soil and heavy metal levels at the beginning (t0) and at the end of the two-year experiment (tf) as affected by N treatments. Within tf values, the bars with the same letters are not significantly different at P ≤ 0.05, according to Duncan's Multiple Range Test. Histograms without letters indicate no significant difference among means. Control = unfertilised treatment; Mineral = mineral fertiliser at 100 kg N ha −1 ; Organic = municipal solid waste at 100 kg N ha −1 .
Article
The application of conventional agricultural practices, e.g. deep soil tillage and repeated, plentiful mineral fertilisation, can lead to a progressive deterioration of soil fertility, especially in Mediterranean environments characterised by scanty rains and high summer temperatures. As a consequence, to maintain high levels of both crop productivity and soil organic matter and to improve some soil properties, a reduction of agricultural inputs and a greater supply of organic material are needed. In the light of these considerations, we carried out a two-year field experiment in Southern Italy to determine the effects of reduced soil tillage and municipal solid waste compost application on growth parameters, production and quality of sugar beet crops, and on both soil chemical characteristics and mineral nitrogen deficit. Two soil tillage depths were compared: conventional tillage, till 40–45 cm and shallow tillage, at 15–20 cm. Within each soil tillage, the following N-fertilising strategies were tested: (1) mineral fertilisation, with 100 kg N ha−1; (2) organic fertilisation with municipal solid waste compost at 100 kg N ha−1; (3) mixed fertilisation, with 50% of organic N as municipal solid waste compost, and 50% of mineral N; and (4) slow-release organic-mineral N fertiliser, at 100 kg N ha−1. All these treatments were compared with a lower level of mineral fertiliser at 50 kg N ha−1, and with an unfertilised control. Our findings show first the absence of a significant difference in root and sucrose yields between reduced tillage and deep tillage; as shown by roots (36.02 t ha−1) and sucrose (3.41 t ha−1) yields for reduced tillage and 35.76 and 3.51 t ha−1, respectively, for the deepest tillage. Secondly, among the N treatments, the mixed organic-mineral N fertilisation gave productions statistically not different from mineral N fertilisation; as shown by root yields (36.38 versus 36.40 t ha−1) and sucrose yields (3.56 versus 3.65 t ha−1). Third, the mixed organic-mineral N induced a reduction of 13.2% in α-amino N content by comparison with the mineral treatment of 100 kg N ha−1. Fourth, our results showed that the applications of the municipal solid waste compost increased the extracted and the humified organic carbon by +27.7 and +25.4%, compared with the mineral fertiliser, and did not raise the content of heavy metals. These findings highlighted that in Southern Italy it is sustainable to adopt alternative sugar beet production, safeguarding crops’ quantitative and qualitative performance, decreasing the production costs and using the natural resources better. sugar beet–soil tillage depths–municipal solid waste–yield–quality–soil characteristics–mineral N deficit
 
Article
Moving towards sustainable agriculture implies exploring the interconnections between farming and the environment, and soil is a key component of sustainability. Mulching is one of the methods to protect and enhance the productivity of the soil. We studied here the effect of mulching applied to mandarin tree rows for weed control in two localities near Tortosa, Spain, to compare its performance with the present chemical weed control system using the herbicide glyphosate. Three mulches were tested in each citrus orchard: rice straw, almond husk and black geotextile. Five plots per treatment, that is, three mulches, glyphosate application and control, were arranged following a randomized block design. Each plot was five trees long and its width was the distance between the two drip-lines. Just before mulch installation, bags containing non-dormant seeds of Amaranthus retroflexus and Diplotaxis erucoides were buried at three depths, and were exhumed one year later. After exhumation, sets of 250 seeds were placed in incubators and cumulative germination was obtained. Moreover, the weed flora was monitored at the two localities on four dates over one year and its total cover was evaluated. Seeds of A. retroflexus and D. erucoides showed the highest germination below almond husk, 90.9% and 96.2%, respectively. In total 74 species were recorded covering the mandarin tree rows. Our results indicated that black geotextile and almond husk controlled the presence of weeds as well as or better than the applications of glyphosate at least during the first year after their introduction. No significant differences were found between the mean weed cover of black geotextile (0.88%), almond husk (4.04%) and herbicide plots (2.04%). Altogether, our results show that mulching is one weed control strategy in mandarin orchards that also provides other benefits in terms of sustainable agriculture, such as soil protection or avoiding herbicide pollution.
 
Concentration of zinc in roots, shoots and grains of lentil plants grown in the absence (•) and presence (•) of a bioinoculant with increasing soil zinc concentrations. 
Article
Though zinc is a plant nutrient at low levels, Zn ions can be highly phytotoxic at higher concentrations found in contaminated soils. Plant growth-promoting rhizobacteria can be used to decrease this toxicity. Indeed, in addition to their role in plant-growth promotion, rhizobacteria also reduce the toxicity of heavy metals. In turn, they can be effective for crops grown in metal-contaminated soils. Here, we isolated a zinc-tolerant plant growth-promoting rhizobacterium, Rhizobium species RL9, from a zinc-contaminated soil and assayed its plant growth-promoting activities in vitro. We found that the rhizobacterium strain RL9 tolerated zinc up to a concentration of 400 μg mL−1 on yeast extract mannitol agar medium. It produced 33 μg mL−1 of indole acetic acid in Luria Bertani broth at 100 μg mL−1 of tryptophan and was positive for siderophore, hydrogen cyanide and ammonia. Such phytohormones released by this strain could help in promoting the growth of legumes. We further tested the effect of rhizobacterium strain RL9 on lentils grown in zinc-amended soil. We found that when the rhizobacterium strain RL9 was added to soil contaminated with Zn at 4890 mg/kg, lentil dry matter increased by 150%, nodule numbers by 15%, nodule dry mass by 27%, leghaemogloblin by 30%, seed yield by 10% and grain protein by 8%, compared with uninoculated plants. We also found that the concentration of zinc was higher in uninoculated plant organs than in the inoculated counterpart. Our findings thus suggest that rhizobacterium strain RL9 could be exploited for bacteria-assisted reduction of zinc toxicity in zinc-contaminated soils due to its intrinsic abilities of expressing growth-promoting substances and reduction of the toxic effects of zinc. lentil–zinc tolerance–zinc uptake–plant-growth promotion
 
Article
Agricultural crop production is largely dependent on inputs of mineral fertilizers. Mineral fertilizer prices are expected to rise as the competition for fossil energy increases. In order to increase the sustainability of crop production, alternatives to commercial mineral fertilizers are needed. Organic residues and fresh biomass are potentially important sources of nitrogen (N) in crop production. A study was conducted to investigate the impact of temperature on the release rate and profile of amino acids from soybean seeds (Glycine max L.) and fresh young shoots of chicory (Cichorium intybus), alfalfa (Medicago sativa) and red clover (Trifolium pratense) under anaerobic conditions. Plant material was incubated in water at either 15 °C or 35 °C, and the temporal release of total N, inorganic N, organic N and amino acids was measured during the 240 h incubation period. Amino acids and other organic N sources constituted significant proportions (20–84%) of the soluble N that was released. The contribution of organic N compounds to total N released decreased when the incubation temperature was raised from 15 °C to 35 °C, whereas the increase in temperature resulted in a higher total N release for only alfalfa and soybean. Amino acid profiles differed with plant material, incubation temperature and incubation length, with release patterns that only in a few cases could be described by first-order kinetics. Irrespective of the source, short-term liquid composting solutions will contain a low amino acid:inorganic N ratio with multiple amino acids present, which has to be taken into account when calculating the fertilizer effect. To conclude, this study reports, to our knowledge for the first time, the multiple amino acid release profiles from four different plant materials incubated under anaerobic conditions. The findings demonstrate that amino acids constitute significant proportions of the total N released and that the release patterns only for some amino acids followed first-order kinetics. plant soaking–nitrogen release–amino acid profile–organic nitrogen
 
Carbon and nitrogen flows in and out of a mixed crop-dairy system and between its main compartments. Gaseous losses from pre-and post-chains are outlined. Adapted from Olesen et al. (2006). 
Chapter
Dairy production systems represent a significant source of air pollutants such as greenhouse gases (GHG), that increase global warming, and ammonia (NH3), that leads to eutrophication and acidification of natural ecosystems. Greenhouse gases and ammonia are emitted both by conventional and organic dairy systems. Several studies have already been conducted to design practices that reduce greenhouse gas and ammonia emissions from dairy systems. However, those studies did not consider options specifically applied to organic farming, as well as the multiple trade-offs occurring between these air pollutants. This article reviews agricultural practices that mitigate greenhouse gas and ammonia emissions. Those practices can be applied to the most common organic dairy systems in northern Europe such as organic mixed crop-dairy systems. The following major points of mitigation options for animal production, crop production and grasslands are discussed. Animal production: the most promising options for reducing greenhouse gas emissions at the livestock management level involve either the improvement of animal production through dietary changes and genetic improvement or the reduction of the replacement rate. The control of the protein intake of animals is an effective means to reduce gaseous emissions of nitrogen, but it is difficult to implement in organic dairy farming systems. Considering the manure handling chain, mitigation options involve housing, storage and application. For housing, an increase in the amounts of straw used for bedding reduces NH3 emissions, while the limitation of CH4 emissions from deep litter is achieved by avoiding anaerobic conditions. During the storage of solid manure, composting could be an efficient mitigation option, depending on its management. Addition of straw to solid manure was shown to reduce CH4 and N2O emissions from the manure heaps. During the storage of liquid manure, emptying the slurry store before late spring is an efficient mitigation option to limit both CH4 and NH3 emissions. Addition of a wooden cover also reduces these emissions more efficiently than a natural surface crust alone, but may increase N2O emissions. Anaerobic digestion is the most promising way to reduce the overall greenhouse gas emissions from storage and land spreading, without increasing NH3 emissions. At the application stage, NH3 emissions may be reduced by spreading manure during the coolest part of the day, incorporating it quickly and in narrow bands. Crop production: the mitigation options for crop production focus on limiting CO2 and N2O emissions. The introduction of perennial crops or temporary leys of longer duration are promising options to limit CO2 emissions by storing carbon in plants or soils. Reduced tillage or no tillage as well as the incorporation of crop residues also favour carbon sequestration in soils, but these practices may enhance N2O emissions. Besides, the improvement of crop N-use efficiency through effective management of manure and slurry, by growing catch crops or by delaying the ploughing of leys, is of prime importance to reduce N2O emissions. Grassland: concerning grassland and grazing management, permanent conversion from arable to grassland provides high soil carbon sequestration while increasing or decreasing the livestock density seems not to be an appropriate mitigation option. From the study of the multiple interrelations between gases and between farm compartments, the following mitigation options are advised for organic mixed crop-dairy systems: (1)actions for increasing energy efficiency or fuel savings becausethey are beneficial in any case, (2) techniques improving efficiency of N management at field and farm levels because they affect not only N2O and NH3 emissions, but also nitrate leaching, and (3) biogas production through anaerobic digestion of manure because it is a promising efficient method to mitigate greenhouse gas emissions, even if the profitability of this expensive investment needs to be carefully studied. Finally, the way the farmer implements the mitigation options, i.e. his practices, will be a determining factor in the reduction of greenhouse gas and NH3 emissions. KeywordsAgriculture-Greenhouse gas-Ammonia-Abatement-Mixed crop-dairy systems-Organic-Livestock-Manure-Grassland-Carbon storage-Soil carbon sequestration
 
Article
Animal slurry contains plant nutrients that are essential for crop production. However, intensive livestock production may lead to a surplus of plant nutrients on farms and, as a consequence, discharge or emission to the environment. In order to ensure that the slurry applied to fields matches the nutrient requirements of the crops, techniques have been developed to reduce the nutrient content of slurry by means of separation. This review discusses the separation technologies used for animal slurry treatment and the physical and chemical processes involved in separation. These processes need to be understood before efficient, reliable and cheap separation technologies that take into account the actual properties of slurry and the likely end-use of the separation products can be developed. A simple separation efficiency expression can be used to assess the efficiency of slurry separation. It is indeed important to measure the amount and composition of the slurry before treatment, the dry-matter-rich fraction and the liquid fraction. The separation efficiency of mechanical separators for the removal of dry matter and phosphorus (P) is ranked as follows: centrifugation > sedimentation > non-pressurized filtration > pressurized filtration. In general, the separation of total N and NH 4+4 follows the same pattern, but the separation efficiency is lower than for dry matter and P. Treatment with a flocculant before separation improves separation efficiency significantly. Of the polyacrylamide polymers tested, high-molecular-weight, linear cationic polymers with a medium charge density (20–40 mol%) were found to be the most efficient flocculants. The best mechanical separation techniques for flocculated slurry are screens or filter belts. The separation efficiency of polyacrylamide-treated slurry can be improved by adding a multivalent ion to coagulate particles and for precipitation of phosphorus. Aluminium sulfate (Al2(SO4)3) or ferric chloride (FeCl3) seem to be very efficient for improving the mechanical separators. Alternatively, the mineral struvite (MgNH4PO4) may be formed by changing the slurry characteristics, such as by the addition of magnesium (Mg) or by increasing the pH to 9. The struvite crystals are removed during solid-liquid separation. The products of the solid—liquid separation may be further treated by evaporation, membrane filtration or ammonia stripping in order to obtain the desired end-products; however, low-maintenance and/or cost-efficient operation of these post-treatments has not yet been demonstrated. The separation should be developed as a whole-system approach, paying attention to parameters such as the value of end-products, environmental consequences and economy.
 
Location of the nine 'management x cultivar' apple orchard systems in the experimental design. Planting distances are 5 m between rows and 2 m within rows. CV: Conventional, LI: Low input, OG: Organic farming. Golden D.: 'Golden Delicious'.
Interacting decision rules between plant protection and other cultural practices for the tested protection systems. Conventional (CV): dash-line arrow, Low input (LI): plain line, Organic (OG): dotted-line.
Article
Recent European incentive policies clearly targeted decreasing pesticide use in all agricultural systems as a key option to reduce environmental hazards and health risks. To reduce pesticide use is challenging in orchards where pesticides are recurrently applied to control numerous pests and diseases, but crucial to improve fruit production sustainability. Agricultural research has provided alternatives to chemical control for the management of a single pest or disease, but has very seldom addressed the design of overall sustainable strategies aiming at reducing pesticide use. New insights permitted by system approaches are now developing. Here, we report the level of pesticide use and the agri-environmental performances of three protection systems of apple orchards surveyed from 2005 to 2008: (1) conventional, (2) low-input and (3) organic farming. To assess the significance of the cultivar in decreasing pesticide use, these protection systems were combined with three cultivars differing in scab susceptibility: ‘Ariane’ (Vf-resistant), ‘Melrose’ (low-susceptibility) and ‘Golden Delicious’ (susceptible). Thus, nine ‘management × cultivar’ apple orchard systems were assessed. The level of pesticide use was the highest in conventional ‘Golden Delicious’ and in ‘Golden Delicious’ plots whatever the protection system. A 43–56% decrease in pesticide use was observed in ‘Ariane’ and ‘Melrose’ in both low-input and organic farming protection systems compared to conventional ‘Golden Delicious’ as reference. Only low-input ‘Melrose’ and low-input ‘Ariane’ systems achieved a level of yield and fruit damages similar to the corresponding conventional cultivars under reduced pesticide use, also permitting reduced environmental impacts. But even the low-input ‘Melrose’ least pesticide-dependant system was far from being pesticide-free, suggesting that current straight-designed mono-clone orchards are hardly appropriate to drastically reduce pesticide use and that the range of commercial apple cultivars should be renewed to offer more robust cultivars. KeywordsOrchard system–Pesticide use–Pest and disease management–Longitudinal survey–Decision rule–Agronomic evaluation–Environmental evaluation–Indicator
 
Article
Iodine deficiency disorders are one of the commonest preventable human health problems. Producing iodine-enriched crops could be an effective way to reduce their epidemicity in many regions. However, the actual knowledge on this issue is limited mostly to studies involving grain crops and inorganic iodine fertilizers such as I− and IO 3−. Moreover, the translocation, transformation and distribution of iodine from soil to plants are not well understood. Here, we studied iodine transfer from soil to vegetables using both inorganic iodine (KI) and organic, seaweed iodine. Greenhouse culture experiments were undertaken to assess the absorption and accumulation of iodine by four vegetables: Chinese cabbage, lettuce, tomato and carrot. We also investigated the dynamic variation of exogenous iodine in soil by applying KI and a composite of seaweed and diatomite. Our results show first that iodine levels in vegetables increase with the increasing addition of iodine. Second, the iodine content in the edible portion ranks as follows: Chinese cabbage (high I) > lettuce > carrot > tomato (low I). The iodine accumulation in the edible portion of the cabbage is thus 2.25 and 4.45 times higher than that of lettuce and carrot, respectively, and 19.67 times higher than that of tomato. In vegetable tissues the iodine distribution is ranked as: root (high I) > leaf > stem > fruit (low I), except for carrot, where the average iodine level in the rhizome is 50% of the shoot. Third, vegetable growth is inhibited when the added iodine concentration is higher than 50 mg kg−1. The order of tolerance against iodine toxicity is ranked as: carrot (high tolerance) > Chinese cabbage > lettuce > tomato (low tolerance). Fourth, the seaweed composite iodine fertilizer demonstrates more potential of durability than KI. Indeed, when KI is added to the soil at 150 mg kg−, the biomass of cabbage, lettuce, tomato and carrot decreases by 34.8%, 41.3%, 46.8% and 17.9%, respectively. By comparison, the biomass decreases are lower, 16.6%, 22.9%, 23.4% and 9.7%, respectively, when applying the seaweed composite. Fifth, after harvest, the residual iodine in soil fertilized with KI is only 56% of the initial addition, which is less than that for seaweed composite. This study is of theoretical importance to understand iodine biogeochemistry and its transfer behavior, and also has practical implications for seeking effective alternatives of iodine biofortification to prevent iodine deficiency disorders.
 
Some benefits of nitrogen fixation by legumes  
Transgenic approaches to engineer abiotic stress tolerance and enhanced nitrogen fixation in legumes 
Agrobacterium-mediated transformation of Medicago truncatula  
Article
Mineral nitrogen deficiency is a frequent characteristic of arid and semi-arid soils. Biological nitrogen fixation by legumes is a sustainable and environmental-friendly alternative to chemical fertilization. Therefore, legumes have a high potential for the reclamation of marginal soils. Such issue is becoming more urgent due to the ever-rising requirement for food and feed, and the increasing extension of salinized and degraded lands, both as a consequence of global change and irrigation practices. This manuscript reviews current research on physiological and molecular mechanisms involved in the response and tolerance to environmental stresses of the Rhizobium–legume symbiosis. We report in particular recent advances on the isolation, characterization, and selection of tolerant rhizobial strains and legume varieties, both by traditional methods and through biotechnological approaches. The major points are the following. (1) Understanding mechanisms involved in stress tolerance is advancing fast, thus providing a solid basis for the selection and engineering of rhizobia and legumes with enhanced tolerance to environmental constraints. (2) The considerable efforts to select locally adapted legume varieties and rhizobial inocula that can fix nitrogen under conditions of drought or salinity are generating competitive crop yields in affected soils. (3) Biotechnological approaches are used to obtain improved legumes and rhizobia with enhanced tolerance to abiotic stresses, paying particular attention to the sensitive nitrogen-fixing activity. Those biotechnologies are yielding transgenic crops and inocula with unquestionable potential. In conclusion, the role of legumes in sustainable agriculture, and particularly, their use in the reclamation of marginal lands, certainly has a very promising future. KeywordsLegume– Rhizobium –Soil–Nitrogen fixation–Nodule–Stress–Salinity–Drought
 
Article
The impact of different fertilisation treatments on soil organic matter, available soil nutrients, mycorrhizal and root properties, as well as on the yield response of winter rye (Secale cereale) was studied in a long-term field trial in Austria under dry site conditions. Winter rye has been grown since 1906 in soils treated with easily soluble mineral fertiliser, farmyard manure, and in an unfertilised control. We found the soil organic matter to be 96% higher in the plots fertilised with farmyard manure compared with easily soluble mineral fertiliser. Available soil phosphorous and potassium contents were at least 136% higher in both fertilised treatments than in the unfertilised control. Arbuscular mycorrhizal colonisation (+46%) of winter rye roots by indigenous arbuscular mycorrhizal fungi, arbuscule frequency (+20%), and the length of the extraradical arbuscular mycorrhizal mycelium (+18%) were higher in the unfertilised control and reduced in the NPK treatment compared with the farmyard manure treatment. The average grain yield of winter rye from 1960 to 2000 increased in all treatments. This increase was higher in the fertilised treatments, +41% for farmyard manure and +60% for easily soluble mineral fertiliser, than in the unfertilised control. Two main effects presumably accounted for the continuously increasing average winter rye yield in all fertilisation treatments: (1) the use of modern winter rye varieties with a higher nutrient efficiency; and (2) an ongoing atmospheric nitrogen deposition. We conclude that the preferential application of farmyard manure, typical for low-input farming systems, resulted in increased levels of soil organic matter, arbuscular mycorrhizal colonisation and arbuscule frequency, supporting soil fertility by an enhanced crop nutrient uptake by arbuscular mycorrhizal fungi under dry site conditions, thus promoting crop yield stability and sustainable plant growth.
 
Maps of the selected squares of 25 km 2 in HIGH (left) and LOW (right). On top: share of maize fields. Below: concentrically implemented isolation perimeters of 50, 100 and 200 m around some fields planted with GM maize. Pictures adapted from the VLM. 
Proportions of non-GM maize fields (fi) and farmers with at least one non-GM maize field (fa) occurring within an isolation perimeter, in relation to the width of isolation perimeters. Scenario S1; situation in HIGH and LOW. Regression formulas are given in Table VII.
Article
Due to the growing cultivation area of genetically modified (GM) maize and the rising number of GM maize varieties commercially available to European farmers, the co-existence between GM and non-GM maize is becoming a burning issue in some European regions. Hence, Member States are imposing or discussing specific co-existence measures to keep the adventitious presence of GM material in non-GM produces below the established labelling threshold. As maize is a cross-pollinated crop that uses wind for the dispersal of its pollen, on-farm co-existence measures may rely on the spatial isolation of GM and non-GM maize fields. In this study, we developed an approach that combines geographic information system (GIS) datasets with Monte Carlo simulations to assess the feasibility of implementing isolation perimeters around GM maize fields, since its practical implementation is rarely addressed in the co-existence debate. More specifically, five scenarios differing in shares and spatial distributions of GM maize were tested for various isolation perimeters in two agricultural areas in Flanders (Belgium). The GIS analyses emphasised the small size of maize fields and their scattered distribution throughout the cropped area. The feasibility of implementing isolation perimeters was largely affected by the (GM) maize share, the spatial distribution of GM maize, and the width of isolation perimeters. The higher the (GM) maize share and the wider the isolation perimeter, the higher the proportions of farmers with non-GM maize fields occurring within the implemented isolation perimeter. Compared with randomly distributed GM maize fields, the clustering of GM maize fields on a larger scale and at the farm level increased the feasibility of implementing isolation perimeters. The approach developed proved to be a valuable tool to quantify the feasibility of implementing isolation perimeters under real agricultural conditions.
 
Article
Buffer strips are uncultivated zones left along the boundaries of crops. Buffer strips are used to eliminate or reduce the environmental impact of herbicides. As the efficiency of buffer strips is improved by the presence of non-crop vegetation, we studied the possible role of growing the perennial grass Festuca arundinacea. We investigated the activity in festuca of glutathione S-transferase (GST), which is an enzyme very active in metabolising herbicides. Our results evidence GST activity, which is enhanced by the following compounds: benoxacor, cloquintocet-mexyl, fenchlorazol-ethyl, fenclorim, fluxofenim and oxabetrinil. These synthetic compounds are named herbicide safeners because they protect crop plants against injury from some herbicides without reducing the action of herbicides against the target weeds. The increases in GST activity were found to be concomitant with changes in Vmax and KM, that are kinetic constants related directly to the enzyme concentration in the protein “pull” and inversely to the substrate-enzyme affinity, respectively. In particular, Vmax increase with KM decrease was observed in response to benoxacor, Vmax increases were found in response to fenchlorazol-ethyl, fenclorim, fluxofenim and oxabetrinil, and KM decrease was observed in response to cloquintocet-mexyl. The GST activity was also found to be enhanced by the safeners when it was tested toward the herbicides terbuthylazine and butachlor as substrates. In particular, the increases in GST toward terbuthylazine ranged in the following decreasing order: 154.6%, 91.7%, 89.2%, 88.3%, 82.5% and 30.8% in response to fluxofenim, fenchlorazol-ethyl, fenclorim, oxabetrinil, benoxacor and cloquintocet-mexyl, respectively. The increases in GST toward butachlor ranged in the following decreasing order: 77.0%, 71.2% 59.0%, 41.0% and 33.1% in response to oxabetrinil, benoxacor, fenclorim, fluxofenim and fenchlorazol-ethyl, respectively. A further test, performed to evaluate the relevance of the above effects on a macro-scale level, evidenced 10.1% and 32.7% increased amounts of metabolised terbuthylazine and butachlor, respectively, in response to the addition of benoxacor safener to the herbicide treatments. These results indicate that herbicide diffusion following the runoff of surface waters can be prevented or significantly reduced by vegetating buffer strips with festuca and by the combination of herbicide and a suitable safener. Festuca arundinacea –glutathione S-transferase–terbuthylazine–butachlor–safeners–detoxification–buffer strips
 
Relationship between SPAD readings from the flag leaf (SPAD L1) and the second leaf (SPAD L2), for 13 cultivars and 3 years. The correlation was significant (P ≤ 0.01).  
An example of change in time-course of SPAD readings around flowering, for the cultivar Vivant in 2006, grown with 2 fertilization strategies (E and L). The dotted lines represent the values for each block; the bold ones represent the average value for the fertilization strategy.  
Article
The performance of cultivars is strongly linked to the growing conditions that vary according to both controlled and uncontrolled experimental factors. Specifically, there is a need to control the efficiency of N use by wheat, Triticum aestivum L., to minimize nitrogen losses and deficiency. The nitrogen nutrition index (NNI) is a precise indicator of nitrogen status but it does not suit the users’ practical constraints because it requires time-consuming measurements and destructive plant sampling at a precise growth stage. Here we tested the soil plant analysis development (SPAD) chlorophyll meter as an alternative to the nitrogen nutrition index (NNI). The chlorophyll meter is a more convenient, leaf clip-on device that determines the relative amount of chlorophyll present in plant leaves. We first identified which leaf should be used; we then compared SPAD and NNI data from various experiments. We also followed SPAD measurements around flowering time to determine a common time span of measurements for all the cultivars of a trial presenting a wide range of earliness. Our results show a non-cultivar-dependent, exponential relationship between the SPAD index and NNI at flowering, with a r2 equal to 0.89. This result implies that the SPAD chlorophyll meter can be used as an alternative to NNI to measure N status in wheat. We also showed that SPAD measurements can be taken before flowering, e.g. during heading, to characterize nitrogen status at flowering. This result provides an organizational leeway to experimenters who can then follow more precisely the N status of their trials. Thus the SPAD index is a good substitute for NNI because it is convenient to use. plant nutrition–nitrogen–chlorophyll meter–SPAD readings–non-destructive testing
 
Article
Blanket fertilizer nitrogen (N) recommendations for large irrigated wheat tracts lead to low N-use efficiency due to field-to-field variability in soil N supply and seasonal variability in yield. To achieve high N use efficiency, a site-specific N management strategy using GreenSeeker™ optical sensor was evaluated. We conducted seven field experiments during 2004–2006 at three locations to define relationships between in-season sensor measurements and yield of wheat and to know whether response of wheat to fertilizer N can be estimated by sensor measurements. During 2005–2007, four field experiments were conducted to assess the sensor-based N management strategy and to work out prescriptive N management to be followed prior to applying sensor-guided fertilizer dose. We observed robust relationships between in-season sensor-based estimates of yield at Feekes 5–6 and 7–8 stages and actual wheat yields. Response of wheat to fertilizer N defined by the sensor was highly correlated with harvest response index. Sensor-guided fertilizer N applications resulted in high yield levels and high N-use efficiency. Application of 90kgN ha-1 at planting or in two equal doses at planting and crown root initiation stage was the appropriate prescriptive fertilizer N management. This study reveals that high N-use efficiency in irrigated wheat can be achieved by replacing blanket fertilizer recommendation by an optical sensor-based N management strategy consisting of applying moderate amount of fertilizer N at planting and crown root initiation stages and sensor-guided fertilizer N dose at Feekes 5–6 or 7–8 stages of wheat. KeywordsIndo-Gangetic Plain–Irrigated wheat–Nitrogen management–Response index–GreenSeeker optical sensor–Potential yield
 
The graph shows the area of an open-top chamber with the subplots for different soil types (soil 1 and soil 2) used in the 1st year and for different water supplies (DRY and WET) used in both years. In the 1st year each open-top chamber was equipped with four lysimeters to grow the plants under the different conditions. In the 2nd year the open-top chambers were operated on an experimental field site.
Effects of two atmospheric CO 2 concentrations (ambient and high CO 2 ) and two watering regimes (WET and DRY) on stem height of wheat plants grown in 1999. Water shortage reduces stem height more under ambient than high CO 2 concentration. Values represent means ± standard error (3 ≤ n ≤ 4). The arrow indicates the start of water shortage.  
Effects of two atmospheric CO 2 concentrations (ambient and high CO 2 ) and two watering regimes (WET and DRY) on chlorophyll content of the three uppermost leaves of the stem of wheat plants grown on a field site in 1999. Chlorophyll was measured nondestructively using the SPAD-502 chlorophyll meter. Water shortage results in an accelerated decline in chlorophyll content, especially in older leaves, and CO 2 enrichment decreases chlorophyll content under WET conditions. Values represent means ± standard error (n = 4). The arrow indicates the start of water shortage.  
Effects of two atmospheric CO 2 concentrations (ambient and high CO 2 ) and two watering regimes (WET and DRY) on the green area index of wheat plants grown on a field site in 1999. Water shortage reduces the green area index and CO 2 enrichment increases the green area index under DRY conditions. Values represent means ± standard error (n = 4). The arrow indicates the start of water shortage.  
Effects of two atmospheric CO 2 concentrations (ambient and high CO 2 ) and two watering regimes (WET and DRY) on percentage absorption of photosynthetically active radiation of the green canopy of wheat plants grown in lysimeters in 1998 (A) and on a field site in 1999 (B). Water shortage reduces percentage radiation absorption in the second half of the vegetation period and this effect is mitigated by CO 2 enrichment, especially in the second year. Values represent means ± standard error (n = 8 and 4, in 1998 and 1999, respectively). The arrow indicates the start of water shortage.  
Article
The atmospheric CO2 concentration is predicted to increase and to generate a rise in the global surface temperature, and change the seasonal precipitation pattern. This could aggravate the severity of summer drought conditions and affect crop yield. We studied the effect of the interaction of CO2 and water supply on seasonal absorption of photosynthetically active radiation and radiation-use efficiency of aboveground biomass production to understand the processes contributing to final yield. Wheat was grown over two years in open-top chambers at present or future (+280 ppmv) atmospheric CO2 concentration and under sufficient water supply or drought stress in lysimeters with a soil depth of 0.4 m (first year) or in the field with unrestricted root growth (second year). Drought stress was started after the first node stage by halving the water supply. Our results show that under sufficient watering, CO2 enrichment did not affect the green area index or seasonal radiation absorption. Drought stress always decreased the green area index and accelerated canopy senescence, which in the second year resulted in a decrease of 23% in the seasonal radiation absorption under the present atmospheric CO2 concentration. CO2 enrichment stimulated the green area index under drought stress in the second year and seasonal radiation absorption was only decreased by 16%. Radiation-use efficiency was reduced by drought and increased by CO2 elevation and the CO2 effect was higher under restricted (+60%) than under sufficient watering (+32%). This implies that CO2 enrichment enhanced final biomass and grain yield by less than 10% under well-watered conditions and by more than 44% under drought stress conditions, respectively. This study indicates that the increase in atmospheric CO2 concentration will attenuate the effects of summer drought on wheat grain yield. CO2 enrichment–drought–leaf area index–radiation absorption–radiation-use efficiency–water-use efficiency–wheat
 
Predicted changes in global surface O 3 concentration from 2000 to 2100. The figure shows the averaged changes in O 3 concentrations 
Major pathways of the transfer of air pollutants to terrestrial surfaces (plant canopies and soil). The thickness of the arrows denotes the relative importance of the respective pathway. Redrawn by courtesy of Dr. Lisa Emberson, SEI York, UK.
Ozone injury on spinach ( Spinacea oleracea cv. Matador). Courtesy: J. Bender, vTI Braunschweig, Germany. 
Ozone injury on spring onion ( Allium fistulosum cv. Polo). Courtesy: J. Bender, vTI Braunschweig, Germany. 
Article
The concentrations of atmospheric compounds such as greenhouse gases, heavy metals and trace gas air pollutants have rapidly changed. Many of these compounds interact with agricultural systems and influence crop performance, both directly by affecting growth and quality or indirectly by altering the plant’s ability to cope with other abiotic and biotic stresses. Some atmospheric compounds have little or no discernible impact on the environment; others reach levels that exceed thresholds for damage to crops. In this review, we analyse the literature on airborne species that directly impact crop growth and health. In Europe and North America emissions of SO2, NOx and heavy metals have declined during the past decades and are currently not considered as a major threat to crops. By contrast, air pollutant emissions have been increasing in rapidly growing regions of Asia, Africa and Latin America. Ozone is the most phytotoxic of the common air pollutants. The widespread distribution of O3 already presents a risk to crop growth and health in many regions of the world. It is concluded that the continuous increase in background O3 concentrations will pose a critical threat to future world food security. Interactions with both biotic and abiotic factors must be taken into account in assessing risks of air pollutants in the field. There is evidence that these indirect effects could be more important under certain circumstances than the direct effects of air pollutants on plants. The parallel rapid increase in atmospheric CO2 concentrations accompanied by climate change has two major implications: (1) a possible benefit to crop growth by direct stimulation of photosynthesis and by mitigation of gaseous air pollutants and water stress; and (2) a threat to crop production due to an enhancement of crop quality losses. Keywordsatmospheric change–carbon dioxide–crops–ozone–pollutant interactions–product quality–yield
 
Relative abundance of Bacillus thuringiensis (Bt) and B. cereus (Bc), and frequency of Bt-positive corn leaf samples collected before and after the insecticide treatment. A-E and F-L are the untreated and treated areas, respectively.
Expression profiles of Bt genes. Lane 1: cry1Ab , lane 2: cry1Ac , lane 3: 16S rDNA, lane 4: 100 bp DNA ladder. 
Article
Bacillus thuringiensis (Bt) is a ubiquitous bacteria widely used as a biopesticide to control a number of important insect pests. Since the mid-1990s, genetically modified (GM) plants expressing Bt genes have been used as an effective tool to control a wide range of insect pests. In recent years, a wide number of articles addressing the environmental impact of genetically modified plants have been published. However, only a few have addressed the occurrence and distribution of the indigenous Bt population in agricultural systems. Here, culturing and molecular methods were used to study the occurrence of Bt harboring insecticidal cry1 genes in a corn field. Samples of corn leaves and soil were collected in July and August 2007 from a 10 ha corn field in Northern Italy. The results showed that the highest Bt density was in leaves located near the soil surface. The incidence of Bt isolates harboring antilepidopteran cry1 genes was 42% of the total tested isolates. Approximately 20% of the Bt isolates harbored the cry1Ab and cry1Ac genes. Similarly to Bt density, the highest abundance of isolates harboring cry1 genes was found in leaves collected near the plant collar. Less than 9% of the Bt isolated from soil harbored cry1 genes. Density of Bt was reduced by application of the insecticide chlorpiryfos. This effect appeared to be due to simply washing off effects of the insecticide treatment to the corn phyllosphere. This study showed that Bt was fairly abundant in the corn agroecosystem and that the high incidence of isolates harboring antilepidopterean cry1 genes could have a role in preserving the sustainability of the agroecosystem. Bacillus thuringiensis–corn phyllosphere–epyphitic bacteria–chlorpyrifos
 
Article
Intercropping legumes with cereals for forage production is a sustainable technique showing several environmental benefits. We studied yields, quality and the growth rate of a 2-year experiment including (1) sole crops of common vetch, barley and winter wheat, and (2) intercrops of common vetch with barley and winter wheat using seeding ratios of 55:45 and 65:35. Our results show that the greatest dry matter yields were obtained with wheat and barley sole crops. The lowest yield was obtained with common vetch sole crop. The intercrops produced about 13–30% more dry matter than the common vetch sole crop, but 12–23% less than cereal sole crops. Further, the growth rate of common vetch and cereals was greater when species were grown as sole crops than in intercrops. Quality components indicated an advantage for the sole crop of common vetch followed by its intercrop with barley at the 65:35 seeding ratio, which exhibited higher crude protein yield than the sole crop of cereals and the other intercrops. The results of this study indicate that common vetch intercrops with barley or winter wheat produced higher dry matter than common vetch sole crop. In addition, the intercrop of common vetch with barley (65:35) provided higher forage quality than the other intercrops. Our study highlights that vetch-cereal intercropping can be used as an alternative cropping system which combines sustainability due to N fixation from common vetch, and high yield and forage quality. cereal–crude protein–growth rate–legume
 
Mata-raton ( Gliricidia sepium Jacquin), approximately three years old. 
Neem ( Azadirachta indica A. Juss.), approximately 15 years old. 
Principal component analysis performed on characteristics of bean, i.e. nodule weight, number of nodules, nodule diameter, root weight, plant weight, root length, number of seeds, number of pods and plant height, cultivated in an agricultural soil with or without an amendment of cow manure, treated with leaf extract of neem (Azadirachta indica) (NEEM treatment) or mata-raton (Gliricidia sepium) (MATARATON treatment), or treated with lambda cyalothrin (CHEMICAL treatment) or left untreated (CONTROL treatment). The first two factors explained 75% of the variation.
Article
Extracts of plants such as neem (Azadirachta indica A. Juss.) and mata-raton (Gliricidia sepium (Jacquin)) are used to control pests. However, certain components of neem, such as azadirachtin, can exert a negative effect on fungi and nitrifying bacteria, and, in turn, can impact the C and N cycles in soil. Nutrient cycling might thus be inhibited and affect the sustainability of an agricultural system in which plant extracts are used to control pests. Here, we investigated the effect of neem extract on microbial activity and N mineralization in soil. We studied the effect of neem and mata-raton leaf extracts on bean growth (Phaseolus vulgaris L.), nodule formation by Rhizobium, soil CO2 emissions and soil N dynamics. Four treatments were applied: (1) “neem treatment”: extracts of neem leaves, (2) “mata-raton treatment”: extracts of mata-raton, (3) “chemical treatment”: a chemical insecticide, lambda cyalothrin, and (4) “control”: untreated plants. Our results show that in non-amended soil the number of nodules in the neem treatment was 18 for beans cultivated. This nodule number was 2.1 times lower compared with the soil treated with lambda cyalothrin (chemical treatment). In manure-amended soil, the number of nodules was 28 in the neem treatment. This nodule number was 1.6 times lower than in the mata-raton treatment. This indicated that neem extracts inhibited Rhizobium in soil and nodule formation in bean. In the manure-amended soil, the emission of CO2 was 1.9 times lower in the neem-treated soil than in the other treatments. The increase in the concentration of NO 3− was 1.03 mg N kg− soil day− in the neem treatment and 4.1 times lower compared with the other treatments. As such, microbial activity was inhibited by the neem extracts when added to the manure-amended soil. It was found that application of neem leaf extract inhibited microbial activity and reduced nodule formation in bean, but lambda cyalothrin or leaf extracts of Gliricidia sepium did not.
 
Field resistance of the transgenic line 3 116 of cv. Koral (left) 
PCR analysis of the transgenic lines that performed best, showing the presence of transgene in the genome. A. An 874 bp PCR product of the cry 3A. B. A 507 bp PCR product of aroA-CP4. C. PCR with primers for potato St.ATP-ase positive control producing 300 bp products. Lanes 1–3 nontransgenic controls of cv. Koral, Bor and Kalina. Lanes 4–6 transgenic lines of cv. Koral (3 12 , 3 116 and 3 203 , respectively), lanes 7 and 8 transgenic lines of cv. Bor (4 41 and 4 103 , respectively), lanes 9and 10 transgenic lines of cv. Kalina (2 18 and 2 98 , respectively) and lane 
Insect bioassay experiment showing the larvae of the Colorado potato beetle on a leaf from a transgenic plant (line 3 12 of cv. 
Article
Colorado potato beetle, Leptinotarsa decemlineata Say, is the most destructive insect pest of potatoes. When the population of beetles is high, plants can be completely defoliated and commercial potato production is nearly impossible without control of the beetle. The beetles have shown a tremendous ability to develop resistance against insecticides. Previously, a biotechnology approach to control Colarado potato beetle based on the use of the synthetic Bt gene was developed. In this article, a transformation procedure for three commercial Bulgarian potato cultivars was developed and potentially commercial transgenic lines have been selected based on field resistance to Colorado potato beetles and yield. Plants were transformed with the Bacillus thuringiensis (Bt) cry3A gene using Agrobacterium-mediated transformation. 110 plants from the three cultivars were regenerated and tested by double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA). The Cry3A protein accumulation varied across the transgenic lines, rating from very low to 71.5 μg/g fresh weight. 21 transgenic lines expressing the Cry3A protein at levels above 10 μg/g fresh weight were tested in two successive years in filed conditions at two different locations of the country. All transgenic lines compared with the controls, nontransgenic potatoes from the respective cultivar, were consistently protected from foliar damages from all developmental stages of the beetle. The comparison of all properties of the tested transgenic lines, including variety phenotypes and tuber yield, allowed the selection of the most promising 2–3 lines per cultivar. Selected lines produced tuber amounts 80–100% higher compared with the control, non-transgenic plants. Those lines were grown for mass propagation during the third year of field experiments. The presence of the transgene in these lines was confirmed with the use of primers specific to the transgene by polymerase chain reaction (PCR). Additionally, the results from the insect bioassay showed that these lines were highly resistant to insect feeding, leading to 100% of mortality of larval populations. In summary, we generated potentially commercial potato lines highly resistant to Colorado potato beetle using Bt technology that may have a profound impact on development of sustainable agriculture in Bulgaria. This is one of the several agriculture biotechnology products entirely developed and tested in Bulgaria. potato–Bt Cry3A–Colorado potato beetle resistance–field tests–genetic transformation
 
Article
Citrus is a crop of major economic importance in Spain, cultivated during the dry season when irrigation is essential to guarantee yields of high quality. As water resources are progressively more insufficient, more effective water management in agriculture is crucial. Deficit irrigation in many agricultural crops has frequently proved to be an efficient tool for improving water-use efficiency. We hypothesise that, despite the effectiveness of deficit irrigation, the most suitable strategy in citrus orchards remains to be defined for Mediterranean environment. In this study, for the period from 2006 to 2008, a 12-year-old orange orchard, Citrus sinensis L. Osb. cv. Navelina, grafted onto Carrizo citrange, C. sinensis L. Osb. × Poncirus trifoliata L. Osb., were subjected under two deficit-irrigation strategies defined as follows: (1) low-frequency deficit irrigation applied according to the plant–water status, and (2) sustained-deficit irrigation with a water-stress ratio of 0.6, defined as the ratio of actual water-limited supply in this treatment related to the water supply of the control treatment. The control treatment was irrigated at 100% of ETC for the entire irrigation season (ETC: crop evapotranspiration). Midday stem–water potential (Ψ stem) and stomatal conductance (g S) were used to estimate the water status of the trees. The lowest Ψ stem and gS values were registered in the deficit-irrigation treatments with a seasonal pattern consistent with the irrigation dynamics applied in each case. Ψ stem and g S values significantly differed from those of the control trees. Although the integrated stress levels were similar in deficit-irrigation treatments, differences in yield and fruit quality were found, having a more positive response to low-frequency deficit irrigation with an increase of 25% in yield in comparison to the sustained-deficit irrigation treatment. Here, we thus demonstrate the significant differences in water productivity. Indeed, water productivity parameter not only depends on the amount of water, but also on the irrigation strategy applied, which promoted substantial water savings without significant impact on yield. The present study highlights that low-frequency deficit irrigation should be adopted as a most appropriate strategy for achieving sustainable water management and attains reasonable yields and improves quality in citrus orchards under Mediterranean semiarid climate.
 
Article
In Morocco, yields of date palms are highly decreased by the pathogen fungi Fusarium oxysporum. To solve this issue, mycorrhizal fungi and biocontrol agents could enhance plant resistance to pathogens. Here, we studied peroxidases in roots and leaves of Phoenix dactylifera in response to inoculation with the fungi Glomus mosseae and Trichoderma harzianum. Date palm plants were harvested 57 weeks after inoculation with mycorrhizal fungi and biocontrol fungi. We measured the dry biomass, arbuscular colonization, cytochemistry of peroxidase, and peroxidase forms and activities in roots and leaves. Our results show that mycorrhization increased the plant dry biomass by about 57%. The rate of mycorrhizal colonization ranged from 25% to 30%. Peroxidase activity in roots colonized by T. harzianum alone was 1.6 times higher than in control plants. Peroxidase activity in roots colonized by G. mosseae and T. harzianum was about 2 times higher than in control plants. Peroxidase activity in leaves increased by + 419% when plants were inoculated by both fungi. The cytochemical results show an accumulation of structural substances in root cell walls after inoculation with T. harzianum. These structural substances may increase the mechanical strength of the host cell walls in order to inhibit pathogen invasion. Peroxidase activities were found in plant cell walls; the tonoplast and host plasmalemma in the chloroplast; mitochondrial membranes; and intercellular spaces of plants inoculated with G. mosseae and T. harzianum. SDS-PAGE analyses of leaf extracts gave a main band at 54 kDa for all the treatments. The stimulatory effect of Trichoderma on the peroxidase activity is a resistance mechanism of date plants to pathogens. The use of Trichoderma could thus be an alternative to chemicals in crop protection. Peroxidase– Trichoderma –date palm–arbuscular mycorrhizal
 
Article
Conventional agriculture is based on a high level of chemical inputs such as pesticides and fertilisers, leading to serious environmental impacts, health risks and loss of biodiversity in agrosystems. The reduction of pesticide use is a priority for intensively sprayed agricultural systems such as orchards. The preservation and promotion of biodiversity within orchards and their boundaries is therefore an issue to explore. Indeed, orchard systems contain high plant diversity and perennial multi-strata designs that provide wealthy resources and habitats to living communities such as beneficial organisms. Orchards thus offer favourable areas to maintain food-webs within the agrosystem, provided that favourable situations are not altered by cultural practices such as applying an excess of pesticides. Here, we analysed literature on the effects of the manipulation of plant diversity and habitats on the control of pests by arthropod and bird communities in apple, pear and peach orchards. Many investigations focus on the role of plant management to enhance biodiversity in orchards but only 22 research reports presenting 30 case studies were dedicated to the study of the ecosystem service provided by plant diversity for orchard pest control. The underlying mechanisms were seldom demonstrated, and the tested grass covers and tree assemblages aimed at favouring either the beneficial complex or only some beneficial species to control one or a few pests. The effect of plant management on pest control was mostly positive (16 cases) or null (9), but also negative in some cases (5). This finding reveals the difficulties of identifying selected plants or plant assemblages for the control of key pests. We conclude that further research is needed to identify the processes involved on different scales for biological control. Orchard systems should be re-designed to optimise ecosystem services provided by biodiversity.
 
Differences in productivity, fermentable carbohydrate and lignin content in some bioethanol feed stocks (Moore 2009)
(continued)
Article
Microalgae are autotrophic microorganisms having extremely high photosynthetic efficiency and are valued as rich source of lipids, hydrocarbons, and other complex oils for biodiesel besides being an invaluable source of bioethanol, biomethane, and biohydrogen. Biodiesel produced from oilseed crops such as jatropha and soy have lower yields per unit land area and threaten food security. Indeed, microalgae have higher oil yields amounting to about 40 times more oil per unit area of land in comparison to terrestrial oilseed crops such as soy and canola. Further, microalgae production does not require arable land for cultivation. Biofuel is regarded as a proven clean energy source and several entrepreneurs are attempting to commercialize this renewable source. Technology for producing and using biofuel has been known for several years and is frequently modified and upgraded. In view of this, a review is presented on microalgae as second generation biofuel. Microalgal farming for biomass production is the biggest challenge and opportunity for the biofuel industry. These are considered to be more efficient in converting solar energy into chemical energy and are amongst the most efficient photosynthetic plants on earth. Microalgae have simple cellular structure, a lipid-rich composition, and a rapid rate of reproduction. Many microalgal strains can be grown in saltwater and other harsh conditions. Some autotrophic microalgae can also be converted to heterotrophic ones to accumulate high quality oils using organic carbon. However, there are several technical challenges that need to be addressed to make microalgal biofuel profitable. The efficiency of microalgal biomass production is highly influenced by environmental conditions, e.g., light of proper intensity and wavelength, temperature, CO2 concentration, nutrient composition, salinities and mixing conditions, and by the choice of cultivation systems: open versus closed pond systems, photobioreactors. Currently, microalgae for commercial purpose are grown mostly in open circular/elongated “raceway” ponds which generally have low yields and high production costs. However, a hybrid system combining closed photobioreactor and open pond is a better option. The biggest hurdle in commercialization of microalgal biofuel is the high cost and energy requirement for the microalgal biomass production, particularly agitation, harvesting, and drying of biomass. In order to conserve energy and reduce costs, algae are often harvested in a two-step process involving flocculation followed by centrifugation, filtration, or micro-straining to get a solid concentration. However, the major bottlenecks in algal biodiesel production within the cell can be identified and handled by adopting a system approach involving transcriptomics, proteomics, and metabolomics. Research and developments in the field of new materials and advanced designs for cultivation in closed bioreactors, use of waste water for biomass production, screening of efficient strains, high-value coproduct strategy, and cutting-edge metabolic engineering are thought to provide the biggest opportunities to substantially improve the cost effectiveness of such production systems. KeywordsBioactive compounds–Biodiesel–Bioethanol–Biohydrogen–Biomethane–Microalgae–Photobioreactors–Wastewater treatment
 
Phases of modelling and simulation and the role of validation and verification (after Schlesinger, 1979). 
Trade-off between model complexity and validation.
Structure of the fuzzy-based integrated index for solar radiation model assessment (F = favourable; U = unfavourable; S = membership function; a = minimum value of F; b = maximum value of U; after Rivington et al., 2005).
Article
The potential of mathematical models is widely acknowledged for examining components and interactions of natural systems, estimating the changes and uncertainties on outcomes, and fostering communication between scientists with different backgrounds and between scientists, managers and the community. For favourable reception of models, a systematic accrual of a good knowledge base is crucial for both science and decision-making. As the roles of models grow in importance, there is an increase in the need for appropriate methods with which to test their quality and performance. For biophysical models, the heterogeneity of data and the range of factors influencing usefulness of their outputs often make it difficult for full analysis and assessment. As a result, modelling studies in the domain of natural sciences often lack elements of good modelling practice related to model validation, that is correspondence of models to its intended purpose. Here we review validation issues and methods currently available for assessing the quality of biophysical models. The review covers issues of validation purpose, the robustness of model results, data quality, model prediction and model complexity. The importance of assessing input data quality and interpretation of phenomena is also addressed. Details are then provided on the range of measures commonly used for validation. Requirements for a methodology for assessment during the entire model-cycle are synthesised. Examples are used from a variety of modelling studies which mainly include agronomic modelling, e.g. crop growth and development, climatic modelling, e.g. climate scenarios, and hydrological modelling, e.g. soil hydrology, but the principles are essentially applicable to any area. It is shown that conducting detailed validation requires multi-faceted knowledge, and poses substantial scientific and technical challenges. Special emphasis is placed on using combined multiple statistics to expand our horizons in validation whilst also tailoring the validation requirements to the specific objectives of the application. accuracy–modelling–multiple statistics–validation
 
Location of the municipality studied.  
Analysis of variance of the size of fields according to land use.  
Landscape heterogeneity in two blocks of land cultivated by two different farmers (aerial picture taken in August 2002). Copyright IGN, Paris, 2002.  
Photo 1. The grey partridge, Perdix perdix L., is a typical farmland species and a culturally important gamebird in Europe. c Baudoux B.
Article
Agricultural changes such as intensification and specialization are thought to be the major source of the severe decline of farmland bird populations observed on large spatial scales and over long time spans in Europe. We studied farmers’ practices at a local level on 22 farms from the Beauce area, France, with regard to habitat preferences of grey partridge, Perdix perdix L. We focused on the study of vegetation cover because it influences grey partridge’s reproduction and survival. The results revealed a high diversity of vegetation cover over the municipal territory. This high diversity can be explained by (1) the difference in the crops cultivated by the farmers, only wheat being cultivated by all the farmers; (2) the diversity of elementary crop sequences implemented, as many as 51 having been identified; and (3) the field size, which varies from 0.5 ha to 57 ha, with 54% of fields smaller than 10 ha. Altogether, this potentially creates six different habitat types, 32% of the arable land surveyed being a likely suitable habitat for the grey partridge. We found that irrigation was the main driving factor of vegetation cover diversity. Indeed irrigation controls the farms’ crop acreage, the crop sequences and their spatial pattern and field size. Nonetheless, irrigation practices show both positive, e.g. crop diversity, and negative aspects, e.g. large fields and clutch failure, for ground-nesting birds such as the grey partridge. Based on these results, a GIS modeling of the municipal landscape related to grey partridge’s habitat requirements is possible and would allow a deeper analysis of the impact of crop diversity on grey partridge populations. cash crop ecosystems–crop sequences–farmland bird biodiversity–grey partridge–technical farm management
 
Top-cited authors
Olivier Therond
  • French National Institute for Agriculture, Food, and Environment (INRAE)
Michel Duru
  • French National Institute for Agriculture, Food, and Environment (INRAE)
Marcos Lana
  • Swedish University of Agricultural Sciences
Miguel A. Altieri
  • University of California, Berkeley
Clara I. Nicholls
  • University of California, Berkeley