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Split Application of Vermicompost: Strategies to Improve Nitrogen Use Efficiency and Productivity of Chickpea
... The mean dehydrogenase and acid phosphatase activity increased up to 23.13 and 42.48% under the application of V treatment as compared to V (control), 3 1 respectively (Table 3). This increase might be due to manure which promote biological and microbial activities and accelerated the breakdown of organic substances in the added manure, which stimulated dehydrogenase activity (Liang et al., 2014;Ghosh et al., 2013;Wang et al., 2007;Patidar et al., 2019). ...
... Ghate et al. (1994). Split application of vermicompost significantly increased microbial population in the rhizosphere of chickpea (Patidar et al., 2019). ...
... increased with split application of vermicompost (Fig. 3) and straw yield with the application of vermicompost was due to the beneficial effect of vermicompost on nutrient availability. The more response of vermicompost as split application in terms of higher yield of wheat may be associated with continuous release of nutrients, including macro and micronutrients resulting higher availability of balanced plant nutrients in soil throughout the crop growth period, especially at critical stages of plants (Patidar et al., 2019;Bejbaruah et al., 2013). ...
Aim: A field experiment was conducted during rabi season to determine the effect of biofertilizers and split application of vermicompost on biological properties (microbial biomass carbon and nitrogen, microbial populations and enzyme activities) in rhizosphere of wheat. Methodology: The experiment was laid out in factorial randomized block design with three replications consisting of twenty treatment combinations. Soil samples were collected from the plots at 0-15 cm depth after harvest of wheat crop and soil biological properties analyzed using standard analytical procedure. Results: The experiment results indicated that among biofertilizers treatments, seed inoculation with Azotobacter + PSB + KMB + ZnSB (B5) resulted in a significant higher soil microbial biomass carbon, microbial biomass nitrogen, population of bacteria, fungi and actinomycetes, dehydrogenase activity and acid phosphatase enzyme activity in comparison to control. Similarly, application of vermicompost as 50 % VC at sowing + 50 % VC at tillering (V3) were obtained improved microbial biomass carbon and nitrogen, microbial population, dehydrogenase activity and acid phosphatase enzyme activity while remaining at par with 75 % VC at sowing + 25 % VC at tillering (V4) proved superior in comparison to rest of the treatments due to continuous supply of nutrients throughout the crop cycle. Grain and straw yield of wheat also increased due to the application of biofertilizers and vermicompost over the control. Interpretation: Biofertilizers (Azotobacter, PSB, KMB and ZnSB) and split application of vermicompost enhanced the soil microbial population and enzymatic activities which sustained the soil health for better wheat production.
... kg/ha) and straw yield (6648.5 kg/ha) were recorded under 50% VC at sowing + 50% VC at tillering(V 3 ) which was significantly higher over the control and basal application (V 2 ) and it remained at par with V 4 . The improvement in grain and straw yield with the application of vermicompost was owing to the beneficial effect of vermicompost on nutrient availability (Patidar et al. 2019). ...
A field experiment was conducted at the Instructional farm, Rajasthan College of Agriculture, Udaipur for two years (2017–18 and 2018–19) during the winter (rabi) season. The experiments were arranged in a randomized block design (RBD) manner with 3 replications. The results showed that, seed inoculation with biofertilizers (Azotobacter + Phosphorus solubilizing bacteria + Potash mobilizing bacteria + Zinc solubilizing bacteria) improved physico-chemical properties of soil except bulk density, particle density, pH, EC and showed higher availability of nutrients over control plot. Whereas in case of vermicompost (VC), physical properties such as BD, PD, porosity, WHC and chemical properties like pH, EC, CEC, OC and available nutrients were found distinctly enhanced under 50% VC at sowing + 50% VC at tillering in post-harvest soil over control. However, 50% VC at sowing + 50% VC at tillering significantly reduced bulk density, particle density, pH and EC. Furthermore, both biofertilizers and split application of vermicompost also significantly improved the productivity of wheat. It is concluded that application of biofertilizers and vermicompost could reliably be used to improve soil physico-chemical properties of wheat cultivated soils.
Soil health is soil capability to operate as living systems, which sustain productivity of biological components, quality of environment, and health of animal and plant. Around the globe food policy-makers' the utmost concern was producing of food in enough quantity including quality to meet the requirements of a burgeoning population. Given the growing consideration to agroforestry, we explored food production system's the most important challenges and opportunities. Nowadays due to the increasing human population along with indiscriminate use of natural resources causes soil degradation and multi-nutrients deficiencies. Many researchers reported unplanned and unscientific agricultural practices, deforestation, over grazing, over-construction and alignment of roads causes poor soil health. Adopting of agroforestry systems improve soil, environment and economical sustainability. The study illustrated that the most noteworthy compensation of agroforestry systems are protection of environment, livelihoods security and soil sustainability. Perennial woody trees-based agroforestry systems have potential to improve soil health through different processes. We describe several distinct, simultaneous mechanisms of agroforestry for soil sustainability and future research areas to fill in knowledge gaps are: i) to know the relationship of agroforestry and soil sustainability, ii) understanding the role of agroforestry in soil sustainability, and iii) exploring the agroforestry system that helps to prevent land degradation. The paper concludes that even though agroforestry systems might present some significant challenges to farming community, it could/should still be considered as a part of the solution and means of improving their livelihoods.
The changing patterns in day to day weather situations, rising CO 2 concentrations, rising sea level, increasing temperature is an indicative of the fact that climate change being encountered by the life of earth at present. Climate change is caused by natural and anthropogenic factors-the natural being due to the periodic tidal pulls exerted by the astronomical bodies on earth's atmosphere and the enhanced one's are due to Changes in the climate through past and present are being evidenced through tephrochronological, dendrochronological, paleonological and archaeological measurements.Climate change has an impact on entire ecosystem, the greatest being on agriculture. Increasing CO 2 concentration increases photosynthetic rates in C3 plants, and reduces transpiration due to decreased stomatal aperture, thus increasing water use efficiency Elevated CO 2 at 330 ppm raised rice yields by 20% and further increase to 700 ppm increased yield by 26.4%. Increased yield is counteracted by a higher temperature that causes moisture stress, delays the maturity of crops due to increased senescence and reduction in grain filling period. Under warm temperature, 2°C above normal, decline in grain yiel d was to the tune of 8.4% in rice and 12.2% in Review Article
Pigeonpea being a Kharif crop most often faces vagaries or uncertainties of rainfall extremities resulting in poor yield realization as it is primarily dependent upon plant population survived until maturity. Maintaining adequate number of plants in presence of both abiotic and biotic stresses is therefore, poses challenge towards sustainability in production. To counteract this, the potential of certain crop contingencies including transplanting of pigeonpea seedling in main field so as to maintain adequate plant population for compensating yield loss during Kharif season is being explored. In this context, a field experiment was carried out at Indian Institute of Pulses Research, Kanpur, India for two years (2011-13) in a sandy loam soil (Typic Ustochrept) with the objectives of studying the feasibility and refining the existing technology of transplanting pigeonpea and its suitability under Eastern Plains of India. The soil was rated with neutral pH and low fertility status in surface soils with descending values towards lower depths. The treatments included the combination of nursery raising technology (paper bags and polyethylene bags), age of seedling (transplanting was made at 3, 4 & 5 weeks after sowing) and land configurations (flat bed and ridge transplanting in main field). The study revealed that irrespective of age of seedling (weeks after transplanting) and material for raising seedling in nursery, an additional seed yield to the tune of 845 kg/ha (27.4%) was realized under transplanting on ridges over the flat bed; and was largely attributed to 9.8% higher pods/ plant. Poly bags raised seedlings transplanted at an early age of 3 weeks on the ridges out yielded over both 4 and 5 weeks. The study also suggested that replacement of missing plants in direct seeding by transplanting poly bags raised seedlings to the extent of 10 % under field condition was feasible and economical in comparison to sole transplanting in the entire field at 3 or 4 weeks (of nursery raising). Thus, the study confirme d the fe asibility of pig eonpea transplanting and explored the possibility of replacing the gaps in plant population due to direct seeding with transplanting of poly bag grown seedlings for realization of higher yield under field conditions of Eastern Indo-Gangetic Plains.
An experiment was conducted to find out the effect of variety, date of transplanting and its interaction on the growth and yield performance of high yielding Boro rice. The experiment comprised five varieties viz., BRRI dhan28, BRRI dhan58, BRRI dhan67, BRRI dhan69, BRRI dhan74 and five dates of transplanting viz., 15 December, 30 December, 15 January, 30 January and 15 February. The experiment was laid out in a randomized complete block design with three replications. Results revealed that growth parameters, crop characters, yield components and yield were significantly influenced by variety, date of transplanting and their interactions. The leaf area index (LAI) and dry matter production hill-1 were highest in BRRI dhan69 when transplanted on 15 January whereas the lowest value was found in BRRI dhan28 when transplanted on 15 February. The number of effective tillers hill-1 (11.80), number of grains panicle-1 (130.90), 1000-grain weight (22.07 g), grain yield (4.96 t ha-1) and straw yield (6.64 t ha-1) were highest in BRRI dhan69 whereas corresponding lowest values were recorded in BRRI dhan28. The crop transplanted on 15 January produced the highest number of effective tillers hill-1 (12.81), highest number of grains panicle-1 (131.20), heaviest 1000-grain weight (21.93 g), highest grain yield (5.36 t ha-1) and highest straw yield (7.71 t ha-1). In case of interaction, the highest grain (5.90 t ha-1) and straw yields (7.87 t ha-1) were recorded in BRRI dhan69 transplanted on 15 January whereas the lowest grain and straw yields were recorded in BRRI dhan28 transplanted on 15 February. Therefore, it can be concluded that BRRI dhan69 along with 15 January transplanting appears as the promising combination in terms of grain and straw yields. J Bangladesh Agril Univ 17(3): 301–308, 2019
Water availability is a major constraint for crop production in semiarid environments. The impact of tillage practices on water potential gradient, water transfer resistance, yield, and water use efficiency (WUEg) of spring wheat was determined on the western Loess Plateau. Six tillage practices implemented in 2001 and their effects were determined in 2016 and 2017 including conventional tillage with no straw (T), no-till with straw cover (NTS), no-till with no straw (NT), conventional tillage with straw incorporated (TS), conventional tillage with plastic mulch (TP), and no-till with plastic mulch (NTP). No-till with straw cover, TP, and NTP significantly improved soil water potential at the seedling stage by 42, 47, and 57%, respectively; root water potential at the seedling stage by 34, 35, and 51%, respectively; leaf water potential at the seedling stage by 37, 48, and 42%, respectively; tillering stage by 21, 24, and 30%, respectively; jointing stage by 28, 32, and 36%, respectively; and flowering stage by 10, 26, and 16%, respectively, compared to T. These treatments also significantly reduced the soil–leaf water potential gradient at the 0–10 cm soil depth at the seedling stage by 35, 48, and 35%, respectively, and at the 30–50 cm soil depth at flowering by 62, 46, and 65%, respectively, compared to T. Thus, NTS, TP, and NTP reduced soil–leaf water transfer resistance and enhanced transpiration. Compared to T, the NTS, TP, and NTP practices increased biomass yield by 18, 36, and 40%; grain yield by 28, 22, and 24%; and WUEg by 24, 26, and 24%, respectively. These results demonstrate that no-till with straw mulch and plastic mulching with either no-till or conventional tillage decrease the soil–leaf water potential gradient and soil–leaf water transfer resistance and enhance sustainable intensification of wheat production in semi-arid areas.
The Climate change affects directly or indirectly the agricultural activity including crops, soils, livestock and pests. Due to global warming it interacts with habitat loss and
fragmentation, introduced and invasive species and population growths and many ecosystems are likely to undergo severe modification. CO2 enrichment increases rate of
photosynthesis in most of the plant species by producing more sugars per unit of light absorbed. A number of strategies are followed up for conservation, multiplication, production, improvement and protection of valuable ornamental species and varieties
Agriculture and climate change are internally correlated with each other in various aspects, as climate change is the main cause of biotic and abiotic stresses, which have adverse effects on the agriculture of a region. The land and its agriculture are being affected by climate changes in different ways, e.g., variations in annual rainfall, average temperature, heat waves, modifications in weeds, pests or microbes, global change of atmospheric CO2 or ozone level, and fluctuations in sea level. The threat of varying global climate has greatly driven the attention of scientists, as these variations are imparting negative impact on global crop production and compromising food security worldwide. According to some predicted reports, agriculture is considered the most endangered activity adversely affected by climate changes. To date, food security and ecosystem resilience are the most concerning subjects worldwide. Climate-smart agriculture is the only way to lower the negative impact of climate variations on crop adaptation, before it might affect global crop production drastically. In this review paper, we summarize the causes of climate change, stresses produced due to climate change, impacts on crops, modern breeding technologies, and biotechnological strategies to cope with climate change, in order to develop climate resilient crops. Revolutions in genetic engineering techniques can also aid in overcoming food security issues against extreme environmental conditions, by producing transgenic plants.
The climate change will affect various crops during the entire growing period owing to extreme weather events. The adaptability of crops to climate variability would acquire significant dimension as frequent occurrence of extreme whether conditions may dictate as to how to cope up with the situation. The climate change will include extreme heat as well as cold waves, increased variability with respect to rabi and kharif crop production, increased extreme whether events in general, erratic onset as well as advances of monsoon, etc. Since farm production is likely to be adversely affected, the climate change will result in increased water management practices, improving land, soil and nutrition management practices, reduction in inefficiency in water use, preservation and enhancement of plant and animal genetic resources, adjustment to the pattern of food consumption, promotion of eco-friendly use adaptation, adaptation to ecosystem based approaches of risk management, shift in cropping pattern, adaptation to integrated farming system and integrated agro forestry systems, etc. There are areas where adaptation programme have already been developed and these include crop improvement, risk financing, drought proofing, disaster management, etc. Adapting agricultural systems to climate change is urgent because its impact is already evident and the trends will continue even if emissions of GHG emissions are stabilized at current levels.
Agroforestry is an ecologically sustainable land use system that maintains increase total yield by combining food crops (annuals) with tree crops (perennials) and/or livestock on the same unit of land. A large hectare is available in the form of boundaries, bunds, wastelands where this system can be adopted. Farmers retain tree of acacia nilotica, acacia catechu, Dalbergia sissoo, Mangifera indica, Zizyphus mauritiana and Gmelina arborea etc in farm land. It plays a crucial role in climate change mitigation especially due to its tree component. Trees accumulate CO2 (which is the most predominant GHG) in their biomass. Agroforestry not only helps in climate change mitigation but also climate change adaptation. It is an established fact that despite our present effort at climate changes mitigation (GHG reduction), there is a more pressing need to cope with the impact of climate change (adaptation). People should be aware about the scope and benefits of Agroforestry and they should participate in implementation and development of Agroforestry in India. Therefore, agroforestry system is economically and ecologically sound practices with enhancement of overall farm productivity, soil enrichment through litter fall, maintaining environmental services such as climate change mitigation (carbon sequestration), phytoremediation, watershed protection and biodiversity conservation.
Alternate wetting and drying (AWD) is a water-saving irrigation technique in a paddy field that can reduce the emission of methane, a potent greenhouse gas (GHG). It is being adopted to Asian countries, but different results are reported in literatures on methane, nitrous oxide emission, and rice productivity under AWD. Therefore, the local feasibility needs to be investigated before its adoption by farmers. The current study carried out a 3-year experiment in an acid sulfate paddy field in Prachin Buri, Thailand. During five crops (3 dry and 2 wet seasons), three treatments of water management were compared: continuous flooding (CF), flooding whenever surface water level declined to 15 cm below the soil surface (AWD), and site-specific AWD (AWDS) that weakened the criteria of soil drying (AWDS). Methane and nitrous oxide emissions were measured by a closed chamber method. Rice grain yield did not significantly (p < 0.05) differ among the three treatments. The amount of total water use (irrigation + rainfall) was significantly reduced by AWD (by 42%) and AWDS (by 34%) compared to CF. There was a significant effect of treatment on the seasonal total methane emission; the mean methane emission in AWD was 49% smaller than that in CF. The seasonal total nitrous oxide emission and the global warming potential (GWP) of methane and nitrous oxide did not differ among treatments. The contribution of nitrous oxide to the GWP ranged 39–62% among three treatments in dry season whereas 3–13% in wet season. The results indicate that AWD is feasible in terms of GHG emission mitigation, rice productivity, and water saving in this site, especially in dry season.
One of the greatest current challenges to human society is ensuring adequate food production and security for a rapidly growing population under changing climatic conditions. Climate change, and specifically rising temperatures, will alter the suitability of areas for specific crops and cultivation systems. In order to maintain yields, farmers may be forced to change cultivation practices, the timing of cultivation, or even the type of crops grown. Alternatively, farmers can change the location where crops are cultivated (e.g., to higher elevations) to track suitable climates (in which case the plants will have to grow in different soils), as cultivated plants will otherwise have to tolerate warmer temperatures and possibly face novel enemies. We simulated these two last possible scenarios (for temperature increases of 1.3 and 2.6°C) in the Peruvian Andes through a field experiment in which several traditionally-grown varieties of potato and maize were planted at different elevations (and thus temperatures) using either the local soil or soil translocated from higher elevations. Maize production declined by 21-29% in response to new soil conditions. The production of maize and potatoes declined by >87% when plants were grown under warmer temperatures, mainly as result of the greater incidence of novel pests. Crop quality and value also declined under simulated migration and warming scenarios. We estimated that local farmers may experience severe economic losses of up to 2300 US$ ha−1 yr−1. These findings reveal that climate change is a real and imminent threat to agriculture and that there is a pressing need to develop effective management strategies to reduce yield losses and prevent food insecurity. Importantly, such strategies should take into account the influences of non-climatic and/or biotic factors (e.g., novel pests) on plant development. This article is protected by copyright. All rights reserved.
Climate change is set to be particularly disruptive in poor agricultural communities. We assess the factors influencing farmers’ choice of climate change adaptation practices and associated impacts on household food security and poverty in Pakistan using comprehensive data from 950 farmers from its major provinces. A probit model was used to investigate the factors influencing the use of climate-change adaptation practices; the censored least absolute deviation (CLAD) was used to analyze the determinants of the number of adaptation practices used; and a propensity score matching (PSM) approach was employed to evaluate the impact of adaptation practices on food security and poverty levels. Adjustment in sowing time (22% households), use of drought tolerant varieties (15%) and shifting to new crops (25%) were the three major adaptation practices used by farmers in the study area. Results show that younger farmers and farmers with higher levels of education are more likely to use these adaptation practices, as do farmers that are wealthier, farm more land and have joint families. The number of adaptation practices used was found to be positively associated with education, male household heads, land size, household size, extension services, access to credit and wealth. Farmers adopting more adaptation practices had higher food security levels (8-13%) than those who did not, and experienced lower levels of poverty (3-6%). Climate change adaptation practices at farm level can thereby have significant development outcomes in addition to reducing exposure to weather risks.
The productivity of rainfed pulses is often threatened by climate change due to unusually high temperature and
drought especially during podding stage. Majority of the pulse-growing regions are vulnerable to climate change
as maximum threshold temperature for tolerance of pulses has already been reached beyond 35oC. Pulses are
unable to derive benefits of high CO2 fluxes, because these crops are grown under climatologically stressed environment. Since both drought and heat are invariably recurrent phenomenon in pulse-growing regions, gene exploration from required germplasm for stress tolerance would remain the possible future hope for evolving newer varieties tolerant to multiple-abiotic stresses. Therefore, strategies have been made to develop climate-resilient varieties based upon screening of large number of gemplasm. Early flowering, short duration, faster biomass accumulation, deep root-system, high water-use efficiency and high root proliferation before onset of terminal drought and heat have been found to be the desired strategies to escape the abiotic stresses. A number of genotypes have been identified which are tolerant to heat stress based on high fertility of pollen and pod formation at temperature beyond 40oC. Drought-specific genes such as Dreb 1A, Dreb 1B and Osmotin are being used for developing drought-tolerant chickpea (Cicer arietinum L.) and pigeonpea [Cajanus cajan (L.) Millsp.] varieties. Similarly, drought specific signal molecule ABA and its role in drought tolerance have been characterized. Identification of linked quantitative loci QTL’s for root and high yield (MAS) and gene mining for abiotic stresses tolerance, have widen the scope towards developing drought tolerance in pulses. Improved agronomic strategies such as restructuring plant types, changing cropping pattern, efficient nutrient and water management, conservation agriculture, seed bank for alternate legume crops, watershed management, micro-irrigation etc. are some of the innovative options to address climate-change issues in pulses. Under changing climatic scenario, the soil organic carbon (SOC) is subjected to depletion and adoption of resource-conservation technologies and best of these management practices have tremendous potential in sequestering carbon in soils. Resource-conservation technologies, conservation-agriculture practices and improved farming practices can reduce emission of greenhouse gases (GHGs) and enhance carbon storage in soils. Moreover, organic system of pulse production increases soil organic matter and cultivation of cover crops and lessens the emissions of gases through production and transportation of synthetic fertilizers due to less demand for them. The inclusion of pulses in crop rotation reduces the need for fertilizer inputs and contributes nitrogen to succeeding crops. Lesser fertilizer requirements are also significantly lowering GHGs emissions.
This research was conducted to assess the influence of long-term tillage system on soil organic carbon, microbial biomass carbon, root biomass and crop yield in spring wheat-field pea rotation fields in a rainfed semi-arid environment from 2013 through 2015. The treatments were; conventional tillage with stubble removed (T); no-till with stubble removed (NT); no-till with stubble retained (NTS) and conventional tillage with stubble incorporated (TS) arranged in a randomised complete block design with three replicates. The soil organic carbon in NTS increased by 16% and 14% over T and NT. Compared with the T and NT, NTS increased soil microbial biomass carbon by 42% and 38% in 0–30 cm depth, respectively. Root biomass was significantly increased in NTS by 47% and 54% over T and NT, respectively. Across the three years, NTS had an average grain yield of 53% and 41% higher than T and NT, respectively. Compared with NTS, T and NT decreased root biomass by 54% and 48%, respectively. In view of the limited and erratic biomass production in this region, integration of no-till with straw mulching is recommended for soil fertility improvement, environmental quality and sustainable crop production. © 2016, Czech Academy of Agricultural Sciences. All rights reserved.
The earth temperature has increased by 0.74°C during the last century (1906 to 2005) due to increase in greenhouse gases through anthropogenic emissions as reported by IPCC. Thus, the increase in temperature is likely to be 1.8-4.0°C by the turn of 21st century resulting in anticipated greater instability in food, feed and fibre production. Increase in temperature can reduce crop duration, change pest populations, hasten mineralization in soils and increase evapotranspiration. It is reported that 40 and 50% less biomass is anticipated in cotton (Gossypium sp.) at 20/10°C and 40/30°C, respectively, with optimum temperature of 30/20°C. However, increase in atmospheric CO2 increases the quantum of yield produced photosynthetically, net photosynthesis, biomass production and ultimate output. Besides higher output, increasing inputs-use efficiency in cultivated crops is also realized and the same at much greater pace in C3 plants (cotton). Study showed that increase in seed cotton yield up to 43% was realized at elevated CO2 of 550 ppm throughout the crop-growing period. Severe sucking pest problem and dominance of weeds are expected in cotton. Thus, in total, elevated CO2 favours cotton growth and yield but higher temperature influences these negatively. The effect of climate change on national cotton production system interpreted that increasing CO2 concentration could help to increase cotton production in all the 3 zones. However, increasing precipitation with decreasing temperature may prolong the vegetative growth and extend the crop duration, which pose difficulties in timely sowing of succeeding rabi crops in north zone. The expected increasing of temperature, decreasing rainfall with erratic distribution in central and south zone leads to frequent wet and dry spell with high évapotranspiration demands. Prolonged dry spell during critical crop growth periods may affect yield. The projected waterlogging coupled with drought by increasing intensity of rainfall may further induce reddening in Bt cotton. Shortening of crop growth periods induced by increasing temperature may facilitate to fit cotton crop into rice (Oryza sativa L.)-fallow cotton system in south zone. Cotton belongs to the C3 plant, which releases CO2 during photorespiration. High external input and overuse of N fertilizers lead to more emission of nitrous oxide. The mitigation strategies should aim to reduce inorganic inputs utilization with more emphasis to nitrogen includes following of integrated nutrient management practice, use of N-fixing Azotobacter and Azospirillum, legumes rotation, application of slow-release nitrogenous fertilizers, adoption of drip-fertigation, incorporation of cotton stalk could reduce fertilizer nitrogen usage. It is evident that application of farmyard manure, mulching greengram (Vigna radiata L. Wilczek), glyricidia sp. and sunnhemp (Crotolaria juncea L.) as green manure recorded 15-32% increase in yield over control and there was considerable build-up of soil available nutrients. Cotton crops grown in future environments will be subjected to a climate for which they are not bred. Cotton species of G barbadense showed more sensitive than G hirsutum. G arboreum is suitable for low and erratic rainfall with drought situations. In saline environment G herbaceum showed better adaptability. The available drought tolerance hirsutum genotypes, like 'LRA 5166', 'KC 2' and 'AKH 081' may show better adaptation. The risk and uncertainty imposed by climate change could be managed by adoption of location-specific intercropping and multi-tier cropping system. In situ soil moisture conservation techniques include contour bunding, graded, narrow or broad ridges or beds separated by furrows, ridges and furrow, opening of furrow after every rows of cotton, black polythene mulch (25 microns), and spreads of crop residue were found to be promising.
Climate change has become most critical issue at the global level, regional and local level to such an extent that climate change is considered as a gravest challenge for the mankind in the present century. No person, no country or no region of the world is immune to climatic changes. Past global efforts at dealing with the problem of global warming (which is most evident form of climate change) concentrated on mitigation, with the aim of reducing and possibly stabilizing greenhouse gas (GHG) concentrations in the atmosphere. As stabilisation of GHG’s primarily depend upon changes in technology, discovery of new and less polluting fuels and with awareness in human behaviour towards mother earth. And all these changes are slow in nature, that’s why adaptation is seen as viable option in reducing the vulnerability to anticipated negative impacts of global warming. Now, at the global level it is increasingly realised that mitigation and adaptation should be perused complement to each other. However, increasing integrating mitigation and adaptation strategies in terms of climate changes are not completely new idea in India and especially in north-western India. This region is characterised by severe and frequent droughts from centuries. And given the rich cultural values of north-western region, local population through their indigenous knowledge systems, have developed a unique from of skills to reduce their vulnerability to variability in local climate. However, this knowledge is rarely taken into consideration in the design and adaptation of modern mitigation and adaptation strategies. This paper is an attempt to highlight some indigenous mitigation and adaptation skills that have been praticesed in North-western India. Paper also attempts to put forward arguments for integrating indigenous knowledge into formal climate change and mitigation strategies.
In an age series (6 to 20 years old; total 10 age groups) effects of Acacia nilotica trees on growth and yield of gram crop was evaluated in a traditional agroforestry system in sub-humid region of Chhattisgarh state. The crown diameter and DBH of trees increased with increasing age of trees. The growth and productivity parameters were taken in three directions and at three distances (1, 3 and 5 m from the tree base). The impact of tree was maximum at 1 m distance from the tree trunk which significantly declined with increasing the distance indicating that greater the distance lesser the effect of the tree. Data were also compared with the growth and yield in the open field. With increase in age, crown diameter and DBH of the Acacia nilotica tree the productivity of gram reduced from 37.73% (in 6 year old tree) to 68.49% (in 20 year old tree). The tree canopy also reduced the density, aboveground biomass, belowground biomass of gram crop. Percent yield reduction showed significant positive co-relation with tree age, crown diameter and DBH of Acacia nilotica trees. These results suggest that Acacia nilotica trees in a traditional agro forestry system need to be pruned regularly during the crop growing season.
A study was conducted in an age series of Acacia
nilotica (L.) Willd. ex Del (6–28 years old)-based traditional
agroforestry system in the sub-humid region of
Chhattisgarh. The effects of this tree on different rice
(Oryza sativa) crop parameters (plant density, plant
height, effective tillers, total aboveground biomass and
grain yield) under natural conditions (without any
management practices in trees) and under tree management
conditions (cutting of 10% of basal tree
branches) were evaluated. The growth and productivity
parameters were taken in three directions (a central
line passing from the centre of the tree bole, and right and left to this central straight line) and at four distances
(1, 3, 5 and 7 m from the tree base). The impact
of the tree on the crop was maximum at 1 m distance
from the tree trunk. The data were also compared
with different crop parameters in the open field (beyond
the reach of the tree canopy). With increase in tree
age, crown diameter and diameter at breast height
(DBH), rice productivity reduced from 4.7 (under 9-
yr-old tree) to 28.8% (under 28-yr-old tree). Whereas
under 6-yr-old tree, there was an increase (4%) in
grain yield. With increase in tree canopy size the plant
density and effective tillers also reduced. Per cent
yield reduction showed significant positive correlation
with tree age, crown diameter and DBH. After the
removal of 10% of basal tree branches (in 12–28-yr-old
trees), the crown diameter of trees was reduced (0.81–
3.77%), plant density (0.05–1%), effective tillers (1.19–
5.8%) and grain yield (1.52–2.92%) increased significantly
and plant height decreased (0.09–1.32%) over
the unmanaged (without cutting the tree branches)
condition.
Conservation agriculture (CA) technologies involve minimum soil disturbance, permanent soil cover through crop residues or cover crops, and crop rotations for achieving higher productivity. In India, efforts to develop, refine and disseminate conservation-based agricultural technologies have been underway for nearly two decades and made significant progress since then even though there are several constraints that affect adoption of CA. Particularly, tremendous efforts have been made on no-till in wheat under a rice-wheat rotation in the Indo-Gangetic plains. There are more payoffs than tradeoffs for adoption of CA but the equilibrium among the two was understood by both adopters and promoters. The technologies of CA provide opportunities to reduce the cost of production, save water and nutrients, increase yields, increase crop diversification, improve efficient use of resources, and benefit the environment. However, there are still constraints for promotion of CA technologies, such as lack of appropriate seeders especially for small and medium scale farmers, competition of crop residues between CA use and livestock feeding, burning of crop residues, availability of skilled and scientific manpower and overcoming the bias or mindset about tillage. The need to develop the policy frame and strategies is urgent to promote CA in the region. This article reviews the emerging concerns due to continuous adoption of conventional agriculture systems, and analyses the constraints, prospects, policy issues and research needs for conservation agriculture in India.
The need to maintain high yields and improved use efficiency has fueled the use of decision tools such as leaf colour chart (LCC) and chlorophyll meter (SPAD meter) in managing fertilizer nitrogen (N) based on leaf colour. Field experiments were conducted during 2011 to 2013 at Ludhiana, India. The objectives of this study were to assess the need for basal N application and to establish critical threshold values of leaf greenness as measured by LCC and SPAD meter for formulating strategies for in-season management of fertilizer N in dry direct-seeded rice (DDSR). Avoiding application of N at planting did not adversely affect rice grain yield, indicating that basal N application in DDSR is not necessary and may lead to reduced N-use efficiency. Monitoring N uptake rate (g m-2 day-1) suggested that during the growing season of DDSR, N uptake rate peaks at two growth stages: at maximum tillering (42 to 56 days after sowing (DAS)) and at panicle initiation stage (70 to 84 DAS). Using the Cate-Nelson procedure, critical LCC and SPAD meter values for fertilizer N application were worked out to be 4 and 37, respectively. Real time fertilizer N management strategy based on applying 30 kg N ha-1 whenever the SPAD meter or LCC readings fell below the critical values maintained rice yields with higher N-use efficiency vis-à-vis the blanket recommendation in the region. The fixed-time variable dose strategy consisted of applying prescriptive doses of 20 kg N ha-1at 14 DAS and 30 kg N ha-1 at 28 DAS and corrective N doses of 30, 40 or 50 kg N ha-1at 49 and 70 DAS depending upon LCC shade to be ≥ 4, between 4 and 3.5 or < 3.5 and SPAD meter readings to be ≥ 40, between 40 and 35 or < 35, respectively. This strategy also resulted in optimal rice yield along with higher N-use efficiency as compared to the blanket recommendation. This study revealed that in DDSR, fertilizer N can be managed more efficiently using LCC and SPAD meter than the current blanket recommendation.
Groundwater recharge sustains the groundwater resources on which there
is global dependence for drinking water and irrigated agriculture. For
many communities, groundwater is the only perennial source of water.
Here, we present a newly compiled 55-year record of groundwater-level
observations in an aquifer of central Tanzania that reveals the highly
episodic occurrence of recharge resulting from anomalously intense
seasonal rainfall. Episodic recharge interrupts multiannual recessions
in groundwater levels, maintaining the water security of the
groundwater-dependent communities in this region. This long-term record
of groundwater storage changes in the semi-arid tropics demonstrates a
nonlinear relationship between rainfall and recharge wherein intense
seasonal rainfall associated with the El Niño Southern
Oscillation and the Indian Ocean Dipole mode of climate variability
contributes disproportionately to recharge. Analysis of the
Intergovernmental Panel on Climate Change AR4 and AR5 multi-model
ensembles for the twenty-first century indicates that projected
increases in extreme monthly rainfall, responsible for observed
recharge, are of much greater magnitude than changes to mean rainfall.
Increased use of groundwater may therefore prove a potentially viable
adaptation to enhanced variability in surface-water resources and soil
moisture resulting from climate change. Uncertainty in the projected
behaviour of the El Niño Southern Oscillation and associated
teleconnections remains, however, high.
If one accepts that climate change is caused by excess carbon dioxide emissions mainly related to excessive energy consumption, reducing it is clearly one very useful way of mitigating climate change. The present work explores how mitigation as well as adaptation strategies for climate change might be transformed by enlisting the help of nanotechnology, the most significant breakthrough technology of the new century. A warning against the premature affirmation of benefits is given. © 2011 Collegium Basilea.
Water conservation is essential to prevent salinity and land degradation in Central Asia. Therefore, field-testing and evaluation
of water conservation methods, i.e. laser land leveling in new farming systems of Central Asia is important task. This in
mind the International Water Management Institute (IWMI) and its regional partner on IWRM FV (IWRM FV project – Integrated
Water Resources Management in Ferghana Valley project is funded by Swiss Development Cooperation (SDC) and conducted jointly
with IWMI and Scientific Information Center of Interstate Coordination Water Commission (SIC ICWC) in the Ferghana Valley
of Central Asia) project SIC ICWC have conducted 3year study of impacts of the Laser leveled land leveling on water use,
productivity and crop yields in northern Tajikistan. The major research question was laser land leveling an effective water
saving tool in the new context of land use and ownership on smaller private plots. Can farmers afford the costs of laser land
leveling and how economically viable is it? These research questions were studied in 5ha laser leveled and neighboring non-leveled
(control) fields for 2004–2006. The results showed that laser land leveling can reduce the water application rate in 2004
by 593M3/ha, in 2005 by 1509M3/ha and in 2006 by 333M3/ha in comparison with the unleveled field, located in the similar agro-ecological conditions. The deep percolation was 8%
lower and run off 24% less than in non-leveled field. The average annual net income from the laser field was 22% higher than
that from the control field. The gross margin from the laser-leveled field were 16. 88 and 171% higher compared to that from
the control field for 2004, 2005 and 2006, and on average was 92% higher. In spite of these positive results, there are hindrances
on wide application of laser land leveling in Tajikistan. These are absence of initial capital of farmers and scattered land
location.
Agriculture is the human enterprise that is most vulnerable to climate change. Tropical agriculture, particularly subsistence
agriculture is particularly vulnerable, as smallholder farmers do not have adequate resources to adapt to climate change.
While agroforestry may play a significant role in mitigating the atmospheric accumulation of greenhouse gases (GHG), it also
has a role to play in helping smallholder farmers adapt to climate change. In this paper, we examine data on the mitigation
potential of agroforestry in the humid and sub-humid tropics. We then present the scientific evidence that leads to the expectation
that agroforestry also has an important role in climate change adaptation, particularly for small holder farmers. We conclude
with priority research questions that need to be answered concerning the role of agroforestry in both mitigation and adaptation
to climate change.
The impact of different arable farming practices on soil erosion is only partly resolved, and the effect of conservation tillage practices in organic agriculture on sediment loss has rarely been tested in the field. This study investigated rainfall-induced interrill sediment loss in a long-term replicated arable farming system and tillage experiment (the FAST trial) with four different cropping systems: (1) organic farming with intensive tillage, (2) organic farming with reduced tillage, (3) conventional farming with intensive tillage, and (4) conventional farming with no tillage. Measurements were carried out under simulated heavy rainfall events with runoff plots in 2014 (fallow land after winter wheat) and 2017 (during maize growth). Organic farming decreased mean sediment delivery compared to conventional farming by 30% (0.54 t ha⁻¹ h⁻¹). This study demonstrated that reduced tillage in organic farming decreased sediment delivery (0.73 t ha⁻¹ h⁻¹) compared to intensively tilled organic plots (1.87 t ha⁻¹ h⁻¹) by 61%. Nevertheless, the combination of conventional farming and no tillage showed the lowest sediment delivery (0.24 t ha⁻¹ h⁻¹), whereas intensively tilled conventional plots revealed the highest delivery (3.46 t ha⁻¹ h⁻¹). Erosion rates were much higher in June during maize growth (2.92 t ha⁻¹ h⁻¹) compared to those of fallow land after winter wheat (0.23 t ha⁻¹ h⁻¹). Soil surface cover and soil organic matter were the best predictors for reduced sediment delivery, and living plant cover from weeds in reduced organic treatments appeared to protect soil surfaces better than plant residues in conventional, no-tillage plots. Soil erosion rates were significantly lower when soil cover was above 30%. In conclusion, this study demonstrates that both organic farming and conservation agriculture reduce soil losses and showed for the first time that reduced tillage practices are a major improvement in organic farming when it comes to soil erosion control.
Life Cycle Assessment (LCA) methodology was used to estimate the environmental impacts and identify the most critical stages (hotspots) of cultivation of three cereal crops typically used for animal feed purposes – barley, rye and sorghum – in the Lombardy region, the most productive crop and livestock area in Northern Italy. The crop variety (out of 3 and 4 varieties of barley and rye, respectively) and cultivation regime (single vs. double cropping of sorghum) with the lowest impacts per kg of crude protein (mass-based functional unit) were identified. Environmental impact categories reported by ReCiPe method were used. According to the results, both Reni and Dank Nowe were the varieties with the lowest environmental impacts for barley and rye varieties, respectively; single cropping of sorghum had lower impacts than double cropping. Impact hotspots included field emissions, agricultural activities and agrochemical (fertilisers and herbicides) production regardless the cropping system considered. Moreover, among the cereals studies, rye was identified as the best environmental alternative. Use of land-based and economic functional units did not change the ranking of systems according to their impacts.
The sensitivity of agricultural output to climate change has often been estimated by modelling crop yields under climate change scenarios or with statistical analysis of the impacts of year-to-year climatic variability on crop yields. However, the area of cropland and the number of crops harvested per growing season (cropping frequency) both also affect agricultural output and both also show sensitivity to climate variability and change. We model the change in agricultural output associated with the response of crop yield, crop frequency and crop area to year-to-year climate variability in Mato Grosso (MT), Brazil, a key agricultural region. Roughly 70% of the change in agricultural output caused by climate was determined by changes in frequency and/or changes in area. Hot and wet conditions were associated with the largest losses and cool and dry conditions with the largest gains. All frequency and area effects had the same sign as total effects, but this was not always the case for yield effects. A focus on yields alone may therefore bias assessments of the vulnerability of agriculture to climate change. Efforts to reduce climate impacts to agriculture should seek to limit production losses not only from crop yield, but also from changes in cropland area and cropping frequency.
The present study was conducted with the objective of documenting and assessing the potential of indigenous knowledge towards adaptation to climate change covering a sample of 200 farmers, hundred each from Himachal Pradesh and Rajasthan representing Himalayan and Arid ecosystems respectively. Documentation of ITK was done using both primary and secondary source of information. In-depth study was designed by combining survey and anthropological approach of participant study. The major documented indigenous knowledge was ‘mind’ cultivation, ‘chal’ to harvest water, ‘apple paste’ to control diseases and ‘siddu’ to protect from extreme cold in Himachal Pradesh. Similarly, the major documented indigenous knowledge of Rajasthan were–Khadin’ farming system to manage drought, ‘kanabandi’ to manage soil and wind storm, ‘tanka’ to harvest water, ‘jupka’ and ‘kothi’ for storing the grain and feed, etc. Beside these, the people of both the ecosystems observed the movement of insects and animals (butterfly, ant, and termite) to forecast the rainfall and other climatic parameter. As the indigenous practices hold high potential to address the issue of climate change, these may be promoted after establishing their scientific validity and rationality. © 2015, National Institute of Science Communication and Information Resources (NISCAIR). All rights reserved.
The purpose of this article is to discuss impact of climate change on nutrient-use efficiency, and dimensions of and strategies to improve nutrient-use efficiency. This article specifically covers site-specific nutrient management to improve nutrient-use efficiency and agronomic strategies to improve nitrogen-use and phosphorus-use efficiency. Plant-based strategies as well as agronomic strategies to improve phosphorus-use efficiency and nitrogen-use efficiency are also discussed. It is suggested that the development of nutrient-use efficient crops using conventional and novel plant breeding methods will bring about improvements in the short to medium term. However, in the long term, improved efficiency alone may not ensure food security. Whole-system changes are needed to develop new products or to relocate land-use activities to different areas as new agro-ecological zones develop as a result of climate change. Productivity growth in agriculture is the key strategy to preserve food security, without expanding production areas. The 4Rs of nutrient stewardship, i.e., balanced nutrition with the Right product at the Right rate in the Right place and at the Right time, must be adopted to enhance nutrient-use efficiency and combat climate change.
Nitrogen (N) input is one of the most important factors in maximizing yields and economic returns to farmers. Of the essentials nutrients, N is required in large quantities, and it is the most mobile and dynamic nutrient in soil systems. It is well-documented that soil physical and chemical properties are spatially variable and affect N dynamics and the mechanisms for its losses. For example, N dynamics could vary from high denitrification N2 losses from ponded areas with low drainage to high NO3 leaching losses from coarse-gravelly areas of the field. Recent developments in new technologies are allowing us to identify, measure, and map these changes across the field. We found that N management using site-specific management zones (SSMZ) that account for soil variability and productivity provides the amounts of N needed to increase yields and maximize the agronomic use efficiency of the applied N. The SSMZ-based N application outperformed treatments that used yield-goal-based and uniform N application rates. Grid-based N application treatments performed as well as the SSMZ for yields but were more inefficient as far as the unit of yields produced by unit of N fertilizer applied. The SSMZ can be used to improve N management and use efficiency of the applied N to increase yields and reduce N losses to the environment.
The impact of increasing atmospheric CO2 concentrations has been studied in a number of field experiments, but little information exists on the response of semiarid rangelands to CO2, or on the consequences for forage quality. This study was initiated to study the CO2 response of the shortgrass steppe, an important semiarid grassland on the western edge of the North American Great Plains, used extensively for livestock grazing. The experiment was conducted for five years on native vegetation at the USDA-ARS Central Plains Experimental Range in northeastern Colorado, USA. Three perennial grasses dominate the study site, Bouteloua gracilis, a C 4 grass, and two C3 grasses, Pascopyrum smithii and Stipa comata. The three species comprise 88% of the aboveground phytomass. To evaluate responses to rising atmospheric CO2, we utilized six open-top chambers, three with ambient air and three with air CO2 enriched to 720 μmol/mol, as well as three unchambered controls. We found that elevated CO2 enhanced production of the shortgrass steppe throughout the study, with 41% greater aboveground phytomass harvested annually in elevated compared to ambient plots. The CO2-induced production response was driven by a single species, S. comata, and was due in part to greater seedling recruitment. The result was species movement toward a composition more typical of the mixed-grass prairie. Growth under elevated CO2 reduced the digestibility of all three dominant grass species. Digestibility was also lowest in the only species to exhibit a CO 2-induced production enhancement, S. comata. The results suggest that rising atmospheric CO2 may enhance production of lower quality forage and a species composition shift toward a greater C3 component.
The canopy temperature of rice at the flowering stage and the soil water content were investigated under different soil water treatments (the soil water contents were 24%, 55%, 90% and 175% at the flowering stage). The canopy temperature was lower than air temperature, and the soil water content significantly influenced the canopy temperature. The lower the soil water content, the higher the canopy temperature, the less the accumulative absolute value of canopy-air temperature difference. Moreover, the maximum difference between treatments and CK in the accumulative absolute value of canopy-air temperature difference appeared at 13:00 p.m. in a day, thus, it could be considered as a suitable measuring time. Under the lowest water content treatment, the peak flowering occurred in the first three days (about 70% of panicles flowered), resulting in shortened and lightened panicle of rice. As to the CK and the high water content treatments, the peak flowering appeared in the middle of flowering duration, with longer panicle length and higher panicle weight. Results indicated the lower the soil water content, the less the filled grain number and grain yield.
Agroforestry is a land use option that increase livelihood security and reduce vulnerability to climate and environmental change. According to Planning Commission report "Greening India", that 33% forest cover can only be achieved through agro-forestry. Agro-forestry has many potential, such as enhance the overall (biomass) productivity, soil fertility improvement, soil conservation, nutrient cycling, micro-climate improvement, carbon sequestration, bio drainage, bio energy and bio fuel etc. Nowadays agro-forestry has gained popularity among farmers, researchers, policy makers and other for its ability to contribute significantly in meeting deficit of tree products, socio-economic and environmental benefits.
This paper provides a case study in which Indigenous knowledge and traditional stories relating to cloud formation, lightning, wind direction, rains, drought, disaster prediction, response, mitigation, and effects of weather on crops are applied in a contemporary context by the tribal peoples of Rajasthan, India. The state of Rajasthan falls in an area of high climate sensitivity, maximum vulnerability and low adaptive capacity. The study documents how individuals in these tribal communities (including Bhil, Meena, Banjara, Kathodi, Rabaris, Sansi and Kanjar) perceive and manage natural disasters and extreme weather events, including their strategies for early detection of coming events and for coping with these events, as well as their perceptions of their short and long term impacts on biodiversity.
The term ‘carbon sequestration’ is commonly used to describe any increase in soil organic carbon (SOC) content caused by a change in land management, with the implication that increased soil carbon (C) storage mitigates climate change. However, this is only true if the management practice causes an additional net transfer of C from the atmosphere to land. Limitations of C sequestration for climate change mitigation include the following constraints: (i) the quantity of C stored in soil is finite, (ii) the process is reversible and (iii) even if SOC is increased there may be changes in the fluxes of other greenhouse gases, especially nitrous oxide (N2O) and methane. Removing land from annual cropping and converting to forest, grassland or perennial crops will remove C from atmospheric CO2 and genuinely contribute to climate change mitigation. However, indirect effects such as conversion of land elsewhere under native vegetation to agriculture could negate the benefit through increased CO2 emission. Re-vegetating degraded land, of limited value for food production, avoids this problem. Adding organic materials such as crop residues or animal manure to soil, whilst increasing SOC, generally does not constitute an additional transfer of C from the atmosphere to land, depending on the alternative fate of the residue. Increases in SOC from reduced tillage now appear to be much smaller than previously claimed, at least in temperate regions, and in some situations increased N2O emission may negate any increase in stored C. The climate change benefit of increased SOC from enhanced crop growth (for example from the use of fertilizers) must be balanced against greenhouse gas emissions associated with manufacture and use of fertilizer. An over-emphasis on the benefits of soil C sequestration may detract from other measures that are at least as effective in combating climate change, including slowing deforestation and increasing efficiency of N use in order to decrease N2O emissions.
Fertilizer nitrogen (N) is one of the major inputs in rice–wheat production systems in South Asia. As fertilizer N has generally
been managed following blanket recommendations consisting of two or three split applications of preset rates of the total
amount of N, improvement in N use efficiency could not be achieved beyond a limit. Feeding crop N needs is the most appropriate
fertilizer N management strategy to further improve N use efficiency. Since plant growth reflects the total N supply from
all sources, plant N status at any given time should be a better indicator of the N availability. The chlorophyll meter and
leaf colour chart have emerged as diagnostic tools which can indirectly estimate crop N status of the growing crops and help
define time and quantity of in-season fertilizer N top dressings in rice and wheat. Supplemental fertilizer N applications
are thus synchronized with the N needs of crop. The chlorophyll meter may not be owned by South Asian farmers individually,
but it can be made available to farmers through village cooperatives, extension specialists, and crop consultants. Leaf colour
chart, a simple and cost-effective device has already penetrated into South Asian farming and increasing numbers of farmers
are finding it helpful in efficiently managing N fertilizers. This paper reviews the results of investigations carried out
using these diagnostic tools in managing need based N applications in rice and wheat in South Asia.
KeywordsCrop N demand-Leaf colour chart-N use efficiency-Rice-SPAD meter-Wheat
Conservation agriculture is claimed to be a panacea for the problems of poor agricultural productivity and soil degradation in sub-Saharan Africa (SSA). It is actively promoted by international research and development organisations, with such strong advocacy that critical debate is stifled. Claims for the potential of CA in Africa are based on widespread adoption in the Americas, where the effects of tillage were replaced by heavy dependence on herbicides and fertilizers. CA is said to increase yields, to reduce labour requirements, improve soil fertility and reduce erosion. Yet empirical evidence is not clear and consistent on many of these points nor is it always clear which of the principles of CA contribute to the desired effects. Although cases can be found where such claims are supported there are equally convincing scientific reports that contradict these claims. Concerns include decreased yields often observed with CA, increased labour requirements when herbicides are not used, an important gender shift of the labour burden to women and a lack of mulch due to poor productivity and due to the priority given to feeding of livestock with crop residues. Despite the publicity claiming widespread adoption of CA, the available evidence suggests virtually no uptake of CA in most SSA countries, with only small groups of adopters in South Africa, Ghana and Zambia. We conclude that there is an urgent need for critical assessment under which ecological and socio-economic conditions CA is best suited for smallholder farming in SSA. Critical constraints to adoption appear to be competing uses for crop residues, increased labour demand for weeding, and lack of access to, and use of external inputs.
Subtropical highlands of the world have been densely populated and intensively cropped. Agricultural sustainability problems resulting from soil erosion and fertility decline have arisen throughout this agro-ecological zone. This article considers practices that would sustain higher and stable yields for wheat and maize in such region. A long-term field experiment under rainfed conditions was started at El Batán, Mexico (2240 m a.s.l.; 19.31°N, 98.50°W; fine, mixed, thermic, Cumulic Haplustoll) in 1991. It included treatments varying in: (1) rotation (continuous maize (Zea mays) or wheat (Triticum aestivum) and the rotation of both); (2) tillage (conventional, zero and permanent beds); (3) crop residue management (full, partial or no retention). Small-scale maize and wheat farmers may expect yield improvements through zero tillage, appropriate rotations and retention of sufficient residues (average maize and wheat yield of 5285 and 5591 kg ha−1), compared to the common practices of heavy tillage before seeding, monocropping and crop residue removal (average maize and wheat yield of 3570 and 4414 kg ha−1). Leaving residue on the field is critical for zero tillage practices. However, it can take some time—roughly 5 years—before the benefits are evident. After that, zero tillage with residue retention resulted in higher and more stable yields than alternative management. Conventional tillage with or without residue incorporation resulted in intermediate yields. Zero tillage without residue drastically reduced yields, except in the case of continuous wheat which, although not high yielding, still performed better than the other treatments with zero tillage and residue removal. Zero tillage treatments with partial residue removal gave yields equivalent to treatments with full residue retention (average maize and wheat yield of 5868 and 5250 kg ha−1). There may be scope to remove part of the residues for fodder and still retain adequate amounts to provide the necessary ground cover. This could make the adoption of zero tillage more acceptable for the small-scale, subsistence farmer whose livelihood strategies include livestock as a key component. Raised-bed cultivation systems allow both dramatic reductions in tillage and opportunities to retain crop residues on the soil surface. Permanent bed treatments combined with rotation and residue retention yielded the same as the zero tillage treatments, with the advantage that more varied weeding and fertilizer application practices are possible. It is important small-scale farmers have access to, and are trained in the use of these technologies.
Many modelling studies examine the impacts of climate change on crop yield, but few explore either the underlying bio-physical processes, or the uncertainty inherent in the parameterisation of crop growth and development. We used a perturbed-parameter crop modelling method together with a regional climate model (PRECIS) driven by the 2071–2100 SRES A2 emissions scenario in order to examine processes and uncertainties in yield simulation. Crop simulations used the groundnut (i.e. peanut; Arachis hypogaea L.) version of the General Large-Area Model for annual crops (GLAM). Two sets of GLAM simulations were carried out: control simulations and fixed-duration simulations, where the impact of mean temperature on crop development rate was removed. Model results were compared to sensitivity tests using two other crop models of differing levels of complexity: CROPGRO, and the groundnut model of Hammer et al. [Hammer, G.L., Sinclair, T.R., Boote, K.J., Wright, G.C., Meinke, H., and Bell, M.J., 1995, A peanut simulation model: I. Model development and testing. Agron. J. 87, 1085–1093].
Soil emission of CO2 is closely linked to soil degradation, decrease in soil organic carbon (SOC) content and decline in soil quality. Enhancing soil quality through adoption of best management practices (BMPs) and soil restoration can increase SOC content and soil productivity, and partially mitigate the greenhouse effect. The C sequestration potential through judicious management of world cropland includes 0.08–0.12 Pg/yr by erosion control, 0.02–0.03 Pg/yr by restoration of severely degraded soils, 0.02–0.04 Pg/yr by reclamation of salt-affected soils, 0.15–0.175 Pg/yr by adoption of conservation tillage and crop residue management, 0.18–0.24 Pg/yr by adoption of improved cropping system and 0.30–0.40 Pg/yr as C offset through biofuel production. The total C sequestration potential of the world cropland is about 0.75–1.0 Pg/yr or about 50% of annual emission of 1.6–1.8 Pg by deforestation and other agricultural activities. This finite soil-C sink could be filled over a 20 to 50-year period, during which energy related emission reductions gradually take effect at global scale. Improving soil quality is a win–win strategy, while increasing productivity it also improves environment and partially mitigates the greenhouse effect. Intensification of farming and increasing biomass production can lead to increased sequestration of C in soils, and to partly meet commitments under the Kyoto Protocol at national and global scales. Global reduction in C emission may have to be substantial if the atmospheric concentration of CO2 is to be stabilized at 550 ppmv. However, realization of this potential would require developing channels of communication between scientists and land managers and policy makers, and providing economic incentives.
Fifty studies (156 experiments) of effects of CO2 concentration ([CO2]) on wheat (Triticum aestivum L.) yield (grain mass at maturity) were analyzed (24 were out-of-doors studies). Only studies controlling [CO2] during all (or most) of the wheat life cycle were considered. Studies were divided into five categories based on the method of controlling [CO2]: laboratory-chamber, glasshouse (greenhouse), closed-top field chamber, open-top field chamber (OTC), and a free-air (chamberless) field CO2 enrichment (FACE) system. Only three studies, all conducted in glasshouses, included subambient-[CO2] treatments , with yield positively related to [CO2] in all three. In superambient-[CO2] experiments with ample water and nutrients and with favorable temperature, [CO2] up to about 2000 ppm increased yield, with a maximum effect (+37%) at about 890 ppm CO2 (according to curve fitting with data from all methods pooled). On average, doubling [CO2] from 350 to 700 ppm increased yield about 31%. Differences in effects of [CO2] on yield between methods of controlling [CO2] could not be judged (or did not exist) because of large variation in yield across chamber (including glasshouse) experiments and too few FACE experiments. Side-by-side comparisons of different methods of controlling [CO2] in which yield was measured were notably lacking. The large variation in effect of [CO2] on yield, even with ample water and nutrients, probably reflected interactions between [CO2] and other factors. With mineral nutrient limitations, effects of [CO2] on yield were small, and with severe nutrient limitations increased [CO2] sometimes reduced yield. With ample nutrients and [CO2] greater than 2000 ppm, yield was also reduced, but this may be of limited significance to field crops for at least the next 100 years. Elevated [CO2] stimulated yield of water-stressed wheat, but usually did not fully compensate for water shortage, though few data were available. Elevated [O3] sometimes reduced positive effects of elevated [CO2] on yield, though again, few data were available. Usually, modest warming (1–4°C) counteracted positive effects of doubled [CO2] on yield. Combinations of rising temperature, [CO2], and [O3] may result in positive or negative effects on wheat yield, though the [CO2]-effect per se will normally be positive. Predictions of effects of rising [CO2] on wheat yield carry with them intrinsic uncertainty.