Background: In search of options to cope with climate change and variability, a trial combining fertilization and improved varieties of millet and cowpea (intercropped or as sole crop) was conducted on three sites (Lemnogo, Tibtenga and Ramdolla) in the northern region of Burkina Faso. The application of cattle manure (3tha1), micro-dose (3ghole1 equivalent to 62kgha1) of a mineral fertilizer composed of 14% N, 23% P2O5 and 14% K2O (NPK), their combination and a control (no manure and no NPK) as four soil fertilization options, two improved varieties of millet (SOSAT-C88 and IKMP5), two varieties of cowpea (KVX 396-4-5-2D and KVX 61-1) and two cropping systems (millet-cowpea intercropping, sole crop) were tested on-farm for two seasons (2013 and 2014). During the third season a survey was conducted on the acceptability by farmers of the tested combinations as a way of buffering or coping with rainfall variability. Results: Two-year trial revealed that the combination of manure and NPK applied to the intercropping of millet and cowpea significantly increased crop production (land equivalent ratio=1.83±0.18 and 1.78±0.20, intercropping millet variety IKMP5 with cowpea KVX 61-1 and intercropping millet variety SOSAT-C88 with cowpea KVX 396-4-5-2D, respectively). During erratic rainfall year, intercropping millet IKMP5 and cowpea KVX 61-1 performed the best, while under well-distributed rainfall conditions, intercropping millet SOSAT-C88 with cowpea KVX 396-4-5-2D displayed higher production, respectively, for millet and cowpea. Some varieties were not well accepted by most farmers (based on a survey of 36 farmers) mainly because of loss in grains before harvest for millet IKMP5 (97%) and high grain attacks by insects in storage for cowpea KVX 61-1 (89%). The alternative for farmers rejecting these varieties could be the intercropping of millet SOSAT-C88 and cowpea KVX 396-4-5-2D fertilized with manure. Conclusions: Making weather forecasts and related agronomic advices available to farmers in this region will allow them to better plan their agricultural practices such as mineral fertilizer application and will also be a great move toward climate-smart agriculture. Developing more performant storage measures that drastically reduce insect attacks for some of the tested varieties (cowpea KVX 61-1, for instance) could contribute to promoting their adoption.
Tag: cropping systems
Impact of Gliricidia sepium intercropping on soil organic matter fractions in a maize-based cropping system
The gliricidia (Gliricidia sepium)/maize intercropping system holds promise for increasing productivity in maize-based cropping systems on depleted soils in Southern Africa. The effect of the intercrop on soil properties was investigated to better understand soil processes underlying maize yield response, soil nutrient recapitalization and soil carbon sequestration. Soil organic matter (SOM) fractions, particulate organic matter (POM), POM-carbon, POM-nitrogen, soil nutrient status and underlying soil characteristics were quantified on the 14th year of a gliricidia/maize intercrop establish in 1991 on a Ferric Lixisol in southern Malawi. A factorial design compared the intercrop and a sole maize crop at three rates of added inorganic nitrogen (N) and phosphorus (P). Gliricidia leaf biomass was incorporated into the maize three times per year. Soil was sampled to a 20 cm depth, post-harvest to analyze biophysical and chemical characteristics of soil organic matter, POM, POM-C and POM-N, as well as inorganic N, available P, exchangeable K+ and particle size distribution. The gliricidia/maize intercrop had a significant and positive effect on SOM, POM, and SOM fractions: SOM was 12% higher, POM 40%, POM-C 62%, and POM-N 86% higher in the gliricidia intercrop compared to sole maize, indicating nitrogen enrichment of POM. Nitrogen fertilizer was associated with modest increases in POM, 15% in gliricidia and 27% in sole maize. The impacts of these changes were directed mostly at increasing maize yields and increasing storage of soil nutrients over the short term, while decreasing the proportion of organic matter stored over the long term. Both the gliricidia/maize intercrop and increasing soil clay content were associated with significantly increased soil CEC. The gliricidia intercrop maintained CEC in coarse-textured soils over a 14-year time span, indicating a role for legume trees in intensified cropping of coarse-textured soils.
Yield stability of cowpea cultivars in rice-based cropping systems: Experimentation and simulation
There is potential in cultivating cowpeas (Vigna unguiculata (L.) Walp.) in rice-based cropping systems in the humid tropics as a source of proteins for humans, forage for ruminants, and for improvement of soil fertility. Seasonal and yearly variability is, however, a major constraint. A statistical stability model and a mechanistic simulation model were used to quantify yield variability of early and medium maturity groups of cowpea cultivars in pre- and post-rice environments at Los Baños, Philippines.Four field experiments, with 24 cultivars in each experiment, were conducted in pre- and post-rice environments, to determine the response of the cultivars to varying moisture and to water table depth regimes, and a stability analysis was performed across the regimes using a statistical model. In the post-rice environment, irrespective of moisture and water table depth regimes, the medium maturing cultivars tended to outyield early maturing cultivars, whereas in the pre-rice environment, early maturity demonstrated a distinct yield advantage.The statistical stability model indicated that medium maturing cultivars performed well in high-yielding environments, whereas in low-yielding environments their yields were comparable with those of early maturing types. However, results of the statistical stability model are limited because of the short time series of basic data. To broaden the analysis, a simulation model of the cowpea crop was calibrated and validated for its performance. Measured and simulated dry weights of crop parts (leaves, stems and pods) and soil moisture contents at 10-cm soil depths throughout the growing season indicated satisfactory performance of the simulation model. Long-term simulation results using the validated model indicate that TVX1948-012F (medium maturity) performs betters (800–2250 kg ha1) than IT82D-889 (early maturity) (430–1620 kg ha1) with a fluctuating shallow water table in the post-rice environment, whereas IT82D-889 is superior (80–1150 kg ha1) to TV1948-012F (30–1150 kg ha1) in the pre-rice environment. Yields are highest and least variable for the 15 January planting in the post-rice environment, and for the 15 April planting in the pre-rice environment.
Cowpea production in rice-based cropping systems of the Philippines—Extrapolation by simulation
There is a growing interest in cultivating cowpeas (Vigna unguiculata (L.) Walp.) in the tropics to meet the protein requirements of small farmers, forage requirements of ruminants, and to attain more sustainable agricultural systems. A mechanistic crop growth model was used to estimate yields of partially irrigated and strictly rainfed crops of IT82D-889, an early maturing cowpea cultivar, and TVX1948-012F, a medium maturing cowpea cultivar. Average yield and yield stability of these cultivars were determined for fields with a shallow and a deep water table before and after the growth of rice (Oryza sativa) in various parts of the Philippines. Long-term simulation results indicated that the yield of TVX1948-012F varied from 100 to 2250 kg ha1, and that of IT82D-889 varied from 50 to 1600 kg ha1 for fields with a shallow water table and for partially irrigated conditions. Yields were greater for the post-rice than for the pre-rice season. Partial irrigation increased long-term biomass compared with those for strictly rainfed situations by 30% in the pre-rice season and by 104% in the post-rice season. Yields were more stable at Davao than at Los Baños or Iloilo. The two maturity classes of cowpea cultivars appear to have somewhat different extrapolation domains. The study demonstrates that mechanistic simulation modelling can be a useful tool to delineate the extrapolation domains of crops and cultivars.
Light interception and evaporation in hedgerow agroforestry systems
Quantifying water lost through evaporation and transpiration in a cropping system is an important tool in adapting a system for semi-arid conditions. During two cropping seasons in eastern Kenya, light interception and soil water content were measured in several different cropping systems: monocultures of cowpea (Vigna unguiculata (L.) Walp.), maize (Zea mays cv. Katumani), Senna spectabilis cv. Embu managed as a hedge, and hedge intercrops of cowpea and maize. These systems differed with respect to plant population density, maximum light interception (44–75%) and canopy height (0.5–2.0 m). Parameters in the EPIC model for leaf area development were derived from periodically-measured light interception in the different systems. Daily light interception predicted from the leaf area was used to partition potential evapotranspiration into potential evaporation and potential transpiration. A simple water balance model was used to predict actual transpiration and actual soil evaporation. Predicted values of water loss during the two seasons correlated closely with measured values (r2 = 0.85 and 0.91; slope = 1.00 and 1.01). In both seasons, the model predicted that soil evaporation comprised approximately half (42–58%) of the estimated evapotranspiration. This study suggests that evapotranspiration can be predicted for a variety of cropping systems when light interception measurements are used in conjunction with a simple model of plant water uptake. It also demonstrates the difficulty of maximizing plant water use in agroforestry systems in semi-arid environments when the canopies of both annual crops and hedges develop simultaneously.
The economics of short rotation improved fallows: evidence from areas of high population density in Western Kenya
This study assesses the economics of improved fallow in the densely-populated areas of western Kenya, where soils are nutrient-depleted. A formal survey of 71 farmers showed that half periodically fallow 10–50% of their land for at least one season, mainly for soil fertility restoration. This is a higher proportion than expected for areas of high population density. An improved-fallow prototype, established by direct seeding Sesbania sesban, an indigenous tree, into the maize crop preceding the fallow, was subjected to an economic analysis, based on twenty farmer-managed trials where the technology was tested. One would intuitively expect that the yield of maize grown after a fallow would need to be at least double that obtained before the fallow in order to compensate for the lost production during the fallow period. Instead, the break-even yield increase following the one-season fallow, compared to continuous cropping, was only 21% of the long rains yield of 600 kg/ha for the base scenario. It was relatively, low, because the foregone maize yield during the fallow was compensated by savings in crop labour. Improved fallow is a promising technique for reclaiming depleted land, especially for households with access to off-farm income or having low labour-to-land ratios. The farm trials facilitated a realistic economic analysis and farmers’ input into the design of the technology to help focus research on improving the practice
Alternatives to slash and burn: a pragmatic approach for mitigating tropical deforestation
How climate-smart is conservation agriculture (CA)? – its potential to deliver on adaptation, mitigation and productivity on smallholder farms in southern Africa
Climate resilient cropping systems are required to adapt to the increasing threats of climate change projected for Southern Africa and to better manage current climate variability. Conservation agriculture (CA) has been proposed among technologies that are climate-smart. For a cropping system to be labelled “climate-smart” it has to deliver three benefits: a) adapt to the effects of climate and be of increased resilience; b) mitigate climate effects by sequestering carbon (C) and reducing greenhouse gas emissions (GHG); and c) sustainably increase productivity and income. Research on smallholder farms from Southern Africa was analysed to assess if CA can deliver on the three principles of climate-smart agriculture. Results from Southern Africa showed that CA systems have a positive effect on adaptation and productivity, but its mitigation potential lags far behind expectations. CA systems maintain higher infiltration rates and conserve soil moisture, which helps to overcome seasonal dry-spells. Increased productivity and profitability were recorded although a lag period of 2–5 cropping seasons is common until yield benefits become significant. Immediate economic benefits such as reduced labour requirements in some systems will make CA more attractive in the short term to farmers who cannot afford to wait for several seasons until yield benefits accrue. The available data summarizing the effects of CA on soil organic C (SOC) and reductions in greenhouse gases, are often contradictory and depend a great deal on the agro-ecological environment and the available biomass for surface residue retention. There is an urgent need for more research to better quantify the mitigation effects, as the current data are scanty. Possible co-interventions such as improved intercropping/relay cropping systems, agroforestry and other tree-based systems may improve delivery of mitigation benefits and need further exploration.
The Challenge of Improving Soil Fertility in Yam Cropping Systems of West Africa
Yam (Dioscorea spp.) is a tuber crop grown for food security, income generation, and traditional medicine. This crop has a high cultural value for some of the groups growing it. Most of the production comes from West Africa where the increased demand has been covered by enlarging cultivated surfaces while the mean yield remained around 10 t tuber ha1. In West Africa, yam is traditionally cultivated without input as the first crop after a long-term fallow as it is considered to require a high soil fertility. African soils, however, are being more and more degraded. The aims of this review were to show the importance of soil fertility for yam, discuss barriers that might limit the adoption of integrated soil fertility management (ISFM) in yam-based systems in West Africa, present the concept of innovation platforms (IPs) as a tool to foster collaboration between actors for designing innovations in yam-based systems and provide recommendations for future research. This review shows that the development of sustainable, feasible, and acceptable soil management innovations for yam requires research to be conducted in interdisciplinary teams including natural and social sciences and in a transdisciplinary manner involving relevant actors from the problem definition, to the co-design of soil management innovations, the evaluation of research results, their communication and their implementation. Finally, this research should be conducted in diverse biophysical and socio-economic settings to develop generic rules on soil/plant relationships in yam as affected by soil management and on how to adjust the innovation supply to specific contexts.
A preliminary classification of fruit-based agroforestry in a highland area of northern Thailand
Tree fruit crops are an increasingly important component of highland cropping systems in northern Thailand. A survey was conducted in three highland hill tribe villages in an upland watershed in Mae Hong Son Province to examine and classify the fruit-based cropping activities used by villagers. Members of ten households in each village were interviewed to establish activities and crop histories for each plot of land held by the household. From the sample of 85 ‘gardens‘ (plots with ten or more fruit trees), a field-level classification structure was developed reflecting function of trees, use and nature of herbaceous intercrops, and pattern of components. Through the classification process, four groups and 11 subsystems of highland tree fruit-based agroforestry were identified. The single most abundant subsystem was ‘mixed home gardens‘. A strong commercial element was also obvious. The survey indicates a very diverse ‘customized’ use of the fruit cropping system. The classification has potential for use in more extensive surveys of the nature of fruit cropping activities in the highlands and as a tool for further analysis in the study area.