No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Watermelon intercropped with cereals under semi-arid conditions: An on-farm study
Abstract
Intercropping is a common practice in Africa, but the advantage compared to sole cropping depends on the crop plants and local agro-ecological conditions.The potential of intercropping maize (Zea mays) or sorghum (Sorghum bicolor) with watermelon (Citrullus lanatus) was tested in two on-farm trials in Southern Mozambique under semi-arid conditions in an area with low and unpredictable rainfall. In the first experiment, plant density, yield and monetary value of sole and intercropping plots of maize with watermelon were determined in 17 farmers’ fields in an area where all crops developed to maturity and harvest. There was a significant reduction in yield of both maize (28.8%) and watermelon (57.8%) in the intercrop compared with the sole crop yields. However, the mean land equivalent ratio of 1.13 for yield showed that intercropping had advantages as, on average, an area planted with sole crops would require 13% more land than an intercrop production to generate the same outcome. In the second experiment, carried out in another area with 16 farmers’ fields, drought was more pronounced and only watermelon developed to maturity. Intercroppings with maize and sorghum resulted in 70% and 69% yield reduction, respectively. In conclusion, watermelon is a good companion crop for intercropping with cereals to mitigate the risk of total crop failure due to drought.
... Recently, watermelon is cultivated as the most promising crop in the study areas of Dacope upazila due to its quick adaptability, economic profit, and high national demand. Many cultivars of watermelon are grown in diverse agroecological zones (Munisse et al. 2012). Watermelon can be able to tolerate salt exposure (Bijalwan et al. 2021).These Rabi season crops in coastal area using different risk mitigation strategies such as mulching, zero tillage, intercropping (Paul et al. 2020;Sarkar et al. 2019;Shahadat et al. 2019;Sarangi et al. 2018), selection of suitable cropping pattern (Mandal et al. 2020;Saha et al. 2019), use of storage ponds for water harvesting and selection of suitable varieties , have demonstrated strategies that are likely to increase productivity, cropping intensity and profitability. ...
A better understanding of area-specific adaptation is crucial to develop and implement proper adaptation strategies that can alleviate the threats of climate change. This study examined the climate change perceptions, determinants and impact of adaptation strategies in saline coastal areas of Bangladesh. Cross-sectional data collected from 100 households producing watermelon in the Rabi season were used for the analysis. Heavy rain was reported as major climate risks of crop loss by the farmers. Mulch was the most widely used climate risk adaptation technique in the study area. Age had a positive influence on farmers’ adoption of the use of mini ponds for irrigation while negative influence on adoption of suitable saline tolerance varieties. Experience in watermelon farming influenced the adoption of suitable salt-tolerant varieties. Multinominal probit and Propensity Score Matching (PSM) results indicated that ‘farmland size owned’ is less likely to use the pond for irrigation and suitable salt tolerant varieties. Membership of a farmer association and perception of decreasing rain influenced farmers’ adoption of mulching, intercropping, use of mini ponds for irrigation, and suitable salt tolerant varieties as adaptation strategies. Policy focuses on the provision of agricultural services and strengthening strong partnerships with different collaborators and development partners for adaptive capacity of climate adaptation strategies would be of effective.
... About 50-53% of watermelon cultivation area during that period was cultivated in new reclaimed land using drip irrigation. Due to wider spacing between the watermelon plants and the large unutilized inter-space can be exploited for growing inter and mixed crops successfully to increase land use efficiency, farmers income, food security, reduction of soil erosion, pest, disease and weed control (Munisse et al., 2012). ...
... Despite most data being on a relatively small number of practices, significant data are available for practices of high interest to the development community. For example, 28% of the data is on practices that diversify production systems such as rotations, intercropping and agroforestry (e.g., Myaka et al. 2006;Munisse et al. 2012;Thierfelder et al. 2013;Nyamadzawo et al. 2008;Chamshama et al. 1998). Therefore, some information exists to reduce the uncertainty about implementing such interventions. ...
More than 500 million USD will soon be invested in climate-smart agriculture (CSA) programmes in sub-Saharan Africa. Improving smallholder farm management is the core of most of these programmes. However, there has been no comprehensive information available to evaluate how changing agricultural practices increases food production, improves resilience of farming systems and livelihoods, and mitigates climate change—the goals of CSA. Here, we present a systematic map—an overview of the availability of scientific evidence—for CSA in five African countries: Tanzania, Malawi, Mozambique, Zimbabwe and Zambia. We conducted a systematic literature search of the effects of 102 technologies, including farm management practices (e.g., leguminous intercropped agroforestry, increased protein content of livestock diets, etc.), on 57 indicators consistent with CSA goals (e.g., yield, water use efficiency, carbon sequestration, etc.) as part of an effort called the “CSA Compendium”. Our search of peer-reviewed articles in Web of Science and Scopus produced 150,567 candidate papers across developing countries in the global tropics. We screened titles, abstracts and full texts against predetermined inclusion criteria, for example that the investigation took place in a tropical developing country and contains primary data on how both a CSA practice and non-CSA control affect a preselected indicator. More than 1500 papers met these criteria from Africa, of which, 153 contained data collected in one of the five countries. Mapping the studies shows geographic and topical clustering in a few locations, around relatively few measures of CSA and for a limited number of commodities, indicating potential for skewed results and highlighting gaps in the evidence. This study sets the baseline for the availability of evidence to support CSA programming in the five countries.
... As a potential drought tolerant plant (Kawasaki et al., 2000;Yokota et al., 2002), it is of particular interest in semi-arid areas of Africa. Under such conditions, it is mostly intercropped with cereals to reduce the risk of complete crop failure and thereby ensuring food security (Munisse et al., 2012). Knowledge on the genetic diversity and differentiation of watermelon resources is useful to develop and implement effective strategies for conservation and sustainable use. ...
Landraces of seed and dessert type watermelons from three provinces of Mozambique with distinct agro-ecological conditions, including humid and semi-dry areas from the north to the south of the country, were analysed to assess their genetic differentiation. Ninety-six accessions (269 plants) were tested with 24 microsatellite markers resulting in 110 alleles. Analysis of molecular variance showed that 63% of the total variation in the plant material could be explained among the accessions, while 37% of the variation was within accessions. Molecular variance between material used for seed extraction and dessert consumption explained 34% of the total variation whereas villages explained 27% of the molecular variation among the sampled locations. Structure analysis revealed that the material could be differentiated into three genetic groups. The seed types clustered in one genetic group, irrespective of provincial origin. Dessert type accessions from the semi-arid south and the central part were assigned to a second genetic group, while accessions from the northern more humid region of the country were assigned to a third genetic group. The observed genetic diversity may reflect farmer selection under different agro-ecological conditions or an introduction of material from different sources into the growing areas.
A greater understanding of the relationship between soil microorganisms and intercropping systems could contribute to the optimization of land use, fostering sustainable and efficient agriculture. This study entails a comparative intercropping assay using cowpea (Vigna unguiculata) and melon (Cucumis melo) under organic management with different patterns and 30% less organic fertilization than that used in monocrops in the first year.
The intercropping system changed the bacterial community structure independently of the intercropping pattern and contributed to an increase in soil nitrogen, phosphorous content and melon crop yield. The intercropped systems were characterized by a higher abundance of Pseudomonas (Proteobacteria), which are related to nutrient cycling, and other beneficial microorganisms.
Mixed cropping of teff (Eragrostis tef ) with faba bean (Vicia faba) was compared with sole cropping in the 2002 and 2003 growing seasons at Holetta Research Centre, in the central highlands of Ethiopia. The treatments were sole teff (25 kg seed ha−1), sole faba bean (200 kg seed ha−1) and 12.5, 25, 37.5, 50 and 62.5% of the sole seed rate of faba bean mixed with a full teff seed rate. A randomized complete block design replicated four times was used. Treatment effects were significant for seed and biomass yields of
each crop species. Increasing the seed rate of faba bean in teff/faba bean mixture increased faba bean seed yield but decreased teff grain yield. Nonetheless, mixed cropping of faba bean with teff increased land use efficiency and gave higher total yields compared to growing either species in sole culture. Teff yield equivalent, land equivalent ratios (LERs) and system productivity index (SPI) of the mixtures exceeded those of sole crops especially when the seed rate of faba bean in the mixture was increased to 50 kg ha−1 (25%) or more. The relatively high crowding coefficient values indicated yield advantages from mixed cropping of the two species. The highest values of teff yield equivalent, LER and SPI were obtained when faba bean was mixed at a rate of 62.5% with the full seed rate of teff.We suggest that, at the current prices of the respective crops, up to 62.5% of faba bean can be mixed in normal teff to get better total yield and income than sole culture of either species.
Sole crops and intercrops of maize (Zea mays L.) and cowpea (Vigna unguiculata L.) were studied at eight planting ratios of maize: cowpea (100:100, 50:100, 100:50, 25:75, 75:25, 50:50, 0:100 and 100:0 ) and two harvest times (milky stage and doughy stage). This experiment was carried during two years (2007 and 2008) on Research Center, University of Zabol, Iran, to investigate the influence of cowpea on the microclimate of their intercrop and sole maize (SM) as control. Measurements of photosynthetically active radiation (PAR), soil temperature (ST), soil moisture (SM) and crop yield were carried out to study the effects of intercropping on crop yield in a cowpea-maize intercropping system in Sistan at southeast of Iran. We found that intercropping increased the amount of absorption PAR compared to sole crop of maize. The highest amount of PAR was obtained at 100% cowpea + 100% maize with no significant difference to 100% cowpea + 50% maize. The lowest amount of PAR was obtained at 75% maize + 25% cowpea. Intercropping system had significant effects on soil temperature and soil moisture (P<0.01). The highest soil temperature was obtained at sole maize and the lowest temperature was at sole cowpea. Soil moisture was lowest at sole maize and highest at sole cowpea. LER (land equivalent ratio) values were greater in all intercropping systems with different planting ratios which indicated yield advantage of intercropping over sole cropping of maize. Results indicate that intercropping can increase light interception and increased shading in intercropping system compared to sole maize and reduce water evaporation and improve conservation of soil moisture. Based on high grain and suitable environmental condition, intercrop productivity compared to sole crop could be selected for improving the productivity of maize/cowpea mixture in the Southeast of Iran.
Farmers in Sistan region experience low crop yields of crops due to low soil fertility. Sole crops and intercrops of maize (Zea mays L.) and cowpea (Vigna unguiculata L.) were studied at eight planting ratios of maize: cowpea (100:100, 50:100, 100:50, 25:75, 75:25, 50:50, 0:100 and 100:0) and two harvest times (milky stage and doughy stage). This experiment was carried during two years (2007 and 2008) on Research Center, University of Zabol, Iran, to investigate the influence of cowpea on the soil fertility and sole maize (SM) as control. Measurements of nitrogen, phosphorous, potassium soil and crop yield were carried out to study the effects of intercropping on crop yield in a cowpea-maize intercropping system in Sistan at southeast of Iran. We found that intercropping increased the amount nitrogen (N), phosphorous (P) and potassium (K) contents compared to sole crop of maize. The highest amount of N, P, and K in soil was obtained at sole cowpea and 100% cowpea + 100% maize with no significant difference to 100% cowpea + 50% maize. The lowest amount of N, P, and K was obtained at sole maize and 75% maize + 25% cowpea. Intercropping system had significant effects on soil fertility and crop yield. LER (land equivalent ratio) values were greater in all intercropping systems with different planting ratios which indicated yield advantage of intercropping over sole cropping of maize. Results indicate that intercropping can increase nutrient elements of soil compared to sole maize and improve conservation of soil fertility. Based on high grain and improve soil fertility intercrop productivity compared to sole crop could be selected for improving the productivity of maize/cowpea mixture in the Southeast of Iran.
Changes in earthworm activity, water runoff, soil erosion, soil physical properties and fertility, and crop growth and yield caused by intercropping either maize (Zea mays L.) and cassava (Manihot esculenta Crantz) (MC) or maize, cassava and ‘egusi’ melon (Citrullus lanatus Thunb.) (MCM) on no-tilled and handhoe-tilled plots were studied in an Alfisol in southwestern Nigeria. Runoff and erosion in no-tilled plots were negligible and were not affected by cropping system. Similarly, soil compaction and infiltration which were lower and higher, respectively, in no-tilled plots than in tilled plots were also unaffected by cropping system. With tillage, however, MCM resulted in lower penetrometer resistance in the soil and erosion than MC, although water infiltration was unaffected. Maximum diurnal soil temperatures were lower with MCM, with lowest values being observed when combined with no-tillage. Similarly, soil fertility was greater with MCM, with highest fertility occurring in no-tilled plots. Combination of no-tillage with MCM resulted, therefore, in a soil environment which was least compacted, most fertile, cooler, had higher water infiltration rates and where water runoff and soil erosion rates were negligible. Inclusion of melon in the crop mixture did not affect grain yield of maize, but reduced cassava tuber yield. Reduction in tuber yield was of the order of 19%.
In organic agriculture, intercropping is receiving increasing attention as it offers potential advantages for increasing sustainability in crop production. However, intercropping can increase competition between crops and weeds. In this study, we analyzed the effects of maize–legume intercrops on the weed community in an organic cropping system. We were concerned only with competition between crops and weeds for light. We recorded a statistically significant negative correlation between the fraction of photosynthetically active radiation (F int PAR) intercepted by the canopy, and both weed density and weed dry matter. Maize–legume intercropping led to a higher soil canopy cover (leaf area index) than sole crops. The lowest values for F int PAR were received in sole crops. Thus, in maize–legume intercrops the decrease in available light for weeds led to a reduction of weed density and dry matter, compared to sole crops. Intercropping maize and legumes considerably reduced the weed density in the intercrop compared with the maize pure stand. Weed suppression by crops was also greater on a low-productivity site than on a high-productivity site. Our results indicate that intercropping could be useful for weed suppression in organic row-crops such as maize and cotton.
The paper analysed how climate change (CC) has shaped African agriculture in the past and how it might impact on African farm economies in the future and what adaptation strategies African farmers have adopted to cope with these changes. The analyses covered all key farming systems and agro-climates of Africa in 11 countries in which data were collected from over 10,000 farm household surveys. Results provided evidence that African agriculture and the welfare of its rural population are vulnerable to CC. The highest risk of future CC damages is associated with specialised crop and livestock farming (mono systems) particularly under dryland conditions in arid and semi-arid regions. This indicates how difficult it is to achieve an African green revolution under the current high reliance on dryland systems (more than 95% of the land) given predicted harsh future climates (warmer and dryer projections) for most of the dryland areas in Africa. It will require substantial public and private investments in expanding irrigation and development of crop varieties and animal breeds that are tolerant to heat, water and low fertility stresses, and in building roads and marketing infrastructures that will improve access to critical inputs (e.g., fertiliser) and output trade. This essentially requires mainstreaming climate sensitivity as an integral component of all agricultural and broader economic development planning and policy design. Although the expected damages are large, many farming systems and communities in Africa face serious limiting conditions which reduce their ability to adapt and hence increase their vulnerability. Among the key factors found to constrain African farmers' ability to adopt effective adaptation measures are poor access to information, capital, technology and markets. Policies aimed at promoting farm-level adaptation need to emphasise the critical role of farmers' education; provision of improved climate, production and market information and the means to implement adaptations through affordable credit facilities. Other needed public interventions to help promote adaptation measures and reduce vulnerability include insurance against climate risks to farmers and provision of safety nets. Copyright The author 2010. Published by Oxford University Press on behalf of the Centre for the Study of African Economies. All rights reserved. For permissions, please email: journals.permissions@oxfordjournals.org, Oxford University Press.
World population is growing exponentially and it has to fulfill their food requirements. An attractive strategy for increasing productivity and labour utilization per unit area of available land is to intensify land use. Intercropping is advanced agro technique of cultivating two or more crops in the same space at the same time have been practiced in past decades and achieved the goal of agriculture. It increases in productivity per unit of land via better utilization of resources, minimizes the risks, reduces weed competition and stabilizes the yield. Several factors influence the intercropping such as maturity of crop, selection of compatible crop, planting density, time of planting as well as socio economic status of farmers and the region. In intercropping, land is effectively utilized and Land Equivalent Ratio (LER) is used to measure the productivity of land. Several findings show the advantages of intercropping by using LER. Cereal-legume intercropping is commonly practiced in world wide. Maize has reorganized as a component crop in most intercropping. In this study, the work carried out by various researches in maize based intercropping are discussed. This work would be useful to the researchers who involves in this field.
A survey was carried out in Berege village, a typical village in the semi-arid area of central Tanzania, to investigate the cultivation methods, productivity, types, storage and uses of water melons (Citrullus vulgaris). Different varieties are grown for human consumption (Tikiti maji) and for livestock feeding (Mahikwi). Production of the livestock variety ranged from 1.6–5.1 tonnes/ha, equivalent to 1.5–4.8 tonnes of water. An experiment to investigate the potential of water melons (Mahikwi) as an alternative to free drinking water for cattle during the dry season in central Tanzania was carried out at the peak of the dry season. Six growing Mpwapwa bulls (1.5 years old), in individual pens, were fed a Cen-chrus ciliaris -based diet supplemented with Acacia tortilis pods (1.5 kg). Three animals received drinking water ad libitum and the remainder received fresh water melons ad libitum for 4 weeks. Intakes of free water (14.6 kg) and water from the water melons (18.4 kg) were not significantly different (P> 0.05). Hay intakes of the 2 groups were similar (3.6 vs 3.4 kg). It is concluded that water melons can be used as an alternative source of water for growing cattle for at least one month during the dry season, with one hectare supplying enough water for a growing bull for about 3–5 months. Further studies with lactating animals for longer periods are warranted.
The effects of combinations of maize, cassava and egusi melon and/or okra on the economic yields of the vegetable crops were studied in Ibadan, Nigeria in 1981–1982.Intercropping significantly reduced the seed yield of egusi melon by 66%, 75%, 78% and 78% in melon/cassava, melon/cassava/okra, melon/cassava/maize and melon/cassava/maize/okra intercrops, respectively, where a high leaf area index (LAI) cassava was used. Similar decreases in the fruit yield of okra under the high LAI cassava were 72%, 90%, 69% and 91% in okra/cassava, okra/cassava/maize, okra/cassava/melon and okra/cassava/maize/melon intercrops, respectively. On average, seed yield of egusi melon and fruit yield of okra were consistently higher where a low LAI cassava was used. The maize component significantly reduced the yields of the vegetable crops. Linear correlation between egusi melon seed yield and LAI (r = 0.889∗∗) was highly significant and higher than that between okra fruit yield and LAI (r = 0.644∗).This study suggests that high LAI cassava morphotypes would not be suitable for intercropping if the farmer expects reasonable intercrop yields from the vegetable components. Cassava cultivars with low LAI and high root yield characteristics and maize varieties that permit sufficient light to the middle and bottom canopy layers would enhance higher intercrop yields of the vegetable components.
In semi-arid areas, pearl millet is an important staple food crop that is traditionally intercropped with cowpea. This study evaluated the water competition between pearl millet and cowpea using deuterated water. At vegetative stage, pearl millet biomass production was lower in the pearl millet-cowpea (PM-CP) combination than in the pearl millet-pigeon pea (PM-PP) and pearl millet-bambara nut (PM-BN) combinations. PM-CP used more water than PM-PP and PM-BN under well-watered conditions; however, all combinations used similar amounts of water under dry conditions. The biomass production, photosynthetic rates, transpiration rates, and midday leaf water potential of pearl millet at early flowering stage were not significantly reduced by mixed planting with cowpea sown two weeks later as compared with single planted pearl millet. When pearl millet and cowpea were sown at the same time, mix planting significantly increased the recovery rates of recently irrigated heavy water in pearl millet, but not in cowpea in both vegetative and early flowering stages. Midday leaf water potential and transpiration rates in pearl millet were lowered by mixed planting but those in cowpea were not. These indicate that the water source of pearl millet is shifted to the recently irrigated and easily accessible water. By contrast, when cowpea was sown two weeks later than pearl millet, this trend was not observed. These results provide new evidence on water competition in the PM-CP intercropping system; cowpea has higher ability to acquire existing soil water than pearl millet when both crops are sown at the same time.
Cassava (Manihot esculenta Crantz)/Maize (Zea mays L.) intercropping is so popular in Nigeria that a cassava/maize intercropping package is recommended to small-scale farmers. Farmers insist on including low-growing vegetables like okra (Abelmoschus esculentus Moench) and egusi melon (Citrullus lanatus Thunb.) in the complex. Studies were conducted in Ibadan to investigate the effects of inclusion of either or both vegetables on gross economic yields and total land productivity of the cassava/maize-plus-vegetables mixture.Tuber yield of cassava in cassava/maize/okra (15.8 t/ha), cassava/maize/egusi melon (15.1 t/ ha) and cassava/maize/okra/egusi melon (14.5 t/ha) did not differ significantly from that in cassava/maize (16.4 t/ha). Maize grain yield was not depressed by intercropping with vegetables. The economic yields of intercropped okra and egusi melon were reduced by more than 50% of their respective sole crop yields.The cassava/maize cropping system yielded highest calories per hectare per day (18.6 × 104 cal ha−1 day−1) but land productivity, based on land equivalent ratio (ler), was higher where the cassava/maize system () included both okra and egusi melon ().
A diagnostic survey carried out in 1997 to obtain baseline information on the farming situation in Transkei area of South Africa, showed that agriculture in this area was characterized by low technological inputs which invariably led to low agricultural outputs. The main farming system of the majority of the farmers (98%) was based on intercropping involving maize, beans and pumpkin combined in an haphazard fashion.
Based on the above findings, two field experiments were set up in 1998 designed to bring out the best planting combinations for maize/beans and maize/pumpkin intercrops which could be introduced to the farmers. Effect of weeding on the intercrops was also investigated.
In both intercrops, intercropping adversely affected the plant heights and circumferences of the component crops. Also, the yield of the individual crop in each intercrop was depressed by intercropping compared with its sole yield. In maize/beans intercrop, the yield of maize was depressed by 15% and that of beans by 13%. However in both intercrops, productivity as measured by Land Equivalent Ratio (LER) was the highest with maize at 10000 plants/ha combined with beans at 150000 plants/ha (2·60) with weeding while the combination with the best LER (1·50) in maize/pumpkin intercrop was at 30000 plants/ha of maize combined with pumpkin at 2500 plants/ha, with weeding. However, before any final recommendation is made, the profitability of each combination has to be considered.
Weeding was found to enhance intercrop yields in maize/bean combination by 35% and by 30% in maize/pumpkin combination.
The effects of various intercropping patterns of maize and melon on soil temperature and moisture content and crop growth and yield were compared in field trials over a two year period. Intercropping raised soil temperature in the upper 10 cm at 0600 h and reduced it at 1000, 1400 and 1800 h, and also increased soil moisture content by about 30%, compared with maize sole cropping. Melon biomass and seed yields were reduced by intercropping but maize growth characters were unaffected. However, the reduction in melon yields was less when grown with maize in widely spaced rows. Maize intercropped with melon in alternate pairs of rows (2:2) gave the best land equivalent ratio (LER).
Intercropping of pearl millet (Pennisetum
glaucum) with clusterbean (Cyamopsis
tetragonoloba) is a common practice in the arid zone of northwestern India. Field experiments were conducted for two years to examine the performance of two contrasting genotypes of each of these crops grown both as sole crops and as intercrops using all possible genotypic combinations of the pearl millet with the clusterbean. The seed yields of both crops were always lower in intercropping than in sole cropping, though the degree of reduction in the seed yield of each intercrop component was influenced greatly by the genotype of its companion crop. The seed yield of both clusterbean genotypes was reduced more when intercropped with the tall and late-maturing pearl millet, MH 179, than with the medium-statured and early-maturing HHB 67. On the other hand, the two clusterbean cultivars had similar effects on intercropped pearl millet. As a result, the highest land equivalent ratios (LERs) were obtained with intercrops containing pearl millet HHB 67 rather than MH 179, while the genotype of clusterbean had little overall effect on LER. The results obtained are discussed in the context of developing cultivars for intercropping.
Symbiotic N2-fixation, N uptake efficiency, biomass- and crop production of cowpea and maize as affected by P source, sole- and intercropped,
and introduction of break crops were studied on a farmer’s fields in semi-arid Tanzania. Cowpea fixed around 60% of its N
from the atmosphere amounting to 70kg Nha−1 under sole and 36kg Nha−1 under intercropping as estimated by the 15N isotope dilution method around peak biomass production. The amount of N2-fixed was 30–40% higher when P was applied as either TSP or MRP whereas cowpea yield were unaffected. Intercropped maize
with 19,000 plant ha−1 accumulated the same amount of N as 38,000 sole cropped maize plants although intercropping reduced the dry matter accumulation
by 25%. The N uptake efficiency of the applied 15N labelled fertiliser was 26%, which equal a total pool of early available plant N of 158kg Nha−1. Under the N deficient conditions, P application did not increase the grain yield of maize. The LER indicate that sole cropping
required 18% more area than intercropping in order to produce the same grain yield, and 35% more land when LER was based on
N uptakes. Introduction of break crops in the maize systems, more than doubled accumulation of dry matter and N in the grain
compared to continuous maize cropping. During maturation sole crop cowpea shedded leaves containing 41kg N ha−1. The current findings underline the importance of crop diversity in Sub Saharan Africa agriculture and emphasise the need
for including all residues, including shedded leaves, in nutrient balance studies.
The capture and utilization of water by sole and intercrops are compared by decomposing crop production/unit area into uptake/unit area (capture) and production/unit uptake (utilization efficiency). Data are from published studies. Comparisons are made by contrasting data from the intercrops against weighted means from the sole crops, with weights based on the proportion of each species in the intercrop. Water capture by intercrops differs from water capture by sole crops only slightly (usually between −6 and +7%). Water-utilization efficiency by intercrops, however, greatly exceeds water-utilization efficiency by sole crops, often by more than 18% and by as much as 99%. Four mechanisms that may account for the consistent increases in water-utilization efficiency by intercrops are postulated on the basis of crop water relations theory but empirical data from intercropping studies are not adequate to test them. The water-utilization efficiency response by intercrops to increased levels of seasonably available water differs from the response by sole crops. Variation in plant density often affects water-utilization efficiency.
Intercropping system of cereals with legume is common in semi-arid tropics of India. However, little attention has been paid to assessing nutrient competition in the system. Seasonal changes in relative dry matter yield (RDY), relative nitrogen yield (RNY), relative phosphorus yield (RPY) and relative potassium yield (RKY) are useful indices to estimate the N, P and K status in intercropping system. The competitive effect of soybean (Glycine max L.) in association with sorghum (Sorghum bicolor L. Moench) was assessed using these indices under six nutrient treatments (0, 75% NPK, 100% NPK, 75% NPK + 5 Mg farmyard manure, 75% NPK + 5 Mg phosphocompost and 75% NPK + 1.5 Mg poultry manure) from a 5-year field experiment conducted in a N and P deficient Vertisol of Central India. The RDY and RNY of sorghum were greater than the values of RDY and RNY of soybean indicating inter-species competition for N between component crops, peak competition being at 80 days after sowing (DAS). Using the concept of RDY and RNY, it was observed that having coincided the maturity period and peak demand for N of both the crops, soil N was exhausted by sorghum because of its strong competitive ability and N was liming for soybean at 80 DAS. Strong competitive ability of sorghum was also evident from higher biomass, root mass, root length density and contribution to the mixture yield. Once sorghum entered its maturity phase, its competitive effect on soybean was greatly reduced. Competition for P between two species is more prominent up to 60 DAS and P was not limiting to none of the species after 60 DAS as the RPY values were equal to corresponding RDY values. Based on RKY value, none of the component species suffered from K deficiency at any stage even if it was not applied. This implied that competition exists for soil N and P but not for K up to 60–80 DAS in soybean/sorghum intercropping system. The result showed that competition between two crops measured in terms of RNY, RPY and RKY under organic-fertilizer was less; however, recorded higher soybean equivalent yield and monetary advantage index than inorganic-fertilizer. The study thus suggests that in soybean/sorghum intercropping system to minimize competition between two crops in N and P deficient Vertisol, application of 75% NPK + FYM/poultry manure/phosphocompost is a viable nutrient management option.
The impacts of climate change, drought and desertification are closely interlinked, and most acutely experienced by populations whose livelihoods depend principally on natural resources. Given the increases in extreme weather events projected to affect the Southern Africa region, it is essential to assess how household and community-level adaptations have been helped or hindered by institutional structures and national policy instruments. In particular, there is a need to reflect on efforts related to the United Nations’ environmental conventions to ensure that policies support the maintenance of local adaptations and help retain the resilience of socio-economic and environmental systems. This paper examines three interlinked drivers of adaptation: climate change, desertification and drought, assessing the extent to which international and national policy supports local adaptive strategies in three countries in southern Africa. We show that while common ground exists between desertification and climate change adaptations at the policy level, they are insufficiently mainstreamed within broader development approaches. Similarly, there are some overlaps between policy-driven and autonomous local adaptations, but the mutually supportive links between them are poorly developed. Further efforts to integrate local adaptation strategies within policy could increase local resilience to environmental change, while also contributing to wider development goals.
Smallholder farmers in East-Africa commonly intercrop maize (Zea mays L.) with grain legumes to maximize utilisation of land and labour, and attain larger crop yields. Conventionally, one legume line is intercropped between each pair of maize lines. This study evaluated the potential of a modified two-by-two staggered arrangement (MBILI) to increase crop yields and economic benefits in two sites in Central Kenya with contrasting soil fertility levels during 7 consecutive seasons. Common beans (Phaseolus vulgaris L.), cowpea (Vigna unguiculata (L.) Walp.) and groundnut (Arachis hypogaea L.) were grown as legume intercrops. The MBILI system resulted in increased maize yields in both sites, and increased cowpea yields in the poor site. In the fertile site, using beans as an intercrop was most profitable, and the MBILI system increased net benefits by 40%, relative to the conventional system. In the poor site, groundnut and cowpea were better adapted, and the MBILI system increased net benefit by 12–37%. Positive effects of the MBILI system were most pronounced in the poor site, but occurred independent of soil fertility level. Rainfall amounts and distribution varied widely, but the MBILI system increased yields both under conditions of ample and inadequate rainfall. N balances were negative with beans and groundnut, but neutral with cowpea as the intercrop. A modest N fertilizer application is therefore essential to sustain yields in the long term, especially when beans or groundnuts are intercropped. In conclusion, the MBILI system, when combined with adjusted nutrient inputs, resulted in superior and robust improvements in crop yields and economic benefits, relative to the conventional intercropping system.
Components of intercrops are often less damaged by pest and disease organisms than when grown as sole crops, but the effectiveness of this escape from attack often varies unpredictably.The presence of associated plants in the intercrop can lead to attack escape in three ways, all involving lower population growth rate of the attacking organism. In one, the associates cause plants of the attacked component to be less good hosts; in the second, they interfere directly with activities of the attacker; and in the third, they change the environment in the intercrop so that natural enemies of the attacker are favoured.Several mechanisms combine to allow multilines and variety mixtures to provide durable protection of cereal crops against specialised, fungal pathogens. Similar approaches may control insects, insect-borne viral pathogens and nematodes. Greater activity of natural enemies of pests in intercrops can control some insect pests and possibly at least one soil pathogen.Although few studies have linked observed changes in populations of the attacking organisms with yield loss, three principles are proposed to explain yield of intercrops to attack. The productivity of an attacked component may be increased several-fold through intercropping. The effect of attack on the land equivalent ratio (LER) is positive where escape occurs, especially if two or more components each escape from their own specific attacker. Use of symptomless carriers of disease can lead to low LERs.Under some conditions, intercropping can usefully contribute to the control of pest or disease populations and the reduction of yield loss. Models of the interaction between cropping systems and their attacking organisms may sometimes clarify issues in a way that many incomplete and short-term experiments fail to do. To overcome the difficulties of experimentation in this complex field, institutional cooperation seems essential.
maps, scale 1:8.800.000 Map(s) inclu.
Drought-affected plants experience more than just desiccation of their organs due to water deficit. Plants transpire 1000 times more molecules of water than of CO2 fixed by photosynthesis in full sunlight. One effect of transpiration is to cool the leaves. Accordingly, drought brings about such multi-stresses as high temperatures, excess photoradiation and other factors that affect plant viability. Wild watermelon serves as a suitable model system to study drought responses of C3 plants, since this plant survives drought by maintaining its water content without any wilting of leaves or desiccation even under severe drought conditions. Under drought conditions in the presence of strong light, wild watermelon accumulates high concentrations of citrulline, glutamate and arginine in its leaves. The accumulation of citrulline and arginine may be related to the induction of DRIP-1, a homologue of ArgE in Escherichia coli, where it functions to incorporate the carbon skeleton of glutamate into the urea cycle. Immunogold electron microscopy reveals the enzyme to be confined exclusively to the cytosol. DRIP-1 is also induced by treating wild watermelon with 150 mM NaCl, but is not induced following treatment with 100 microM abscisic acid. The salt treatment causes the accumulation of gamma-aminobutyrate, glutamine and alanine, in addition to a smaller amount of citrulline. Citrulline may function as a potent hydroxyl radical scavenger.
Sorghum/pigeonpea and millet/groundnut intercropping systems are described to illustrate temporal and spatial complementarity and the magnitude of yield advantages that can be achieved in intercropping compared with sole cropping. The concept of considering environmental resource use in terms of ‘resource capture’ and ‘resource conversion efficiency’ is outlined and is then used to examine the resources of light, water and nutrients. Some implications for sugarcane intercropping are considered with particular emphasis on complementarity, resource use and the need for clear evaluation of objectives.
The challenge of integrated water resource management for improved rural livelihoods: Managing risks, mitigating drought and improving water productivity in the water scarce Limpopo Basin
- R Brito
- S Famba
- P Munguambe
- N Ibraimo
- C Julaia
Brito, R., Famba, S., Munguambe, P., Ibraimo, N. and Julaia, C. (2009). Profile of Limpopo Basin in Mozambique (A
contribution to the Challenge Program on Water and Food, CPWF Project 17, 'The challenge of integrated water
resource management for improved rural livelihoods: Managing risks, mitigating drought and improving water
productivity in the water scarce Limpopo Basin', WaterNet Working Paper 11). Harare: WaterNet.