Efforts were made to reach the planned outcomes of enhancing soil-crop-water and nutrient interactions for improving the efficiency of nutrients and water as well as organic materials (woody litter, composted urban waste) used alone or in combination with mineral fertilizers. For this, studies were carried out in Burkina Faso and Senegal either with sole crops (sorghum, millet, cowpea and groundnut) or their combinations. The findings revealed an increased soil carbon stock, millet yield, NPK fertilizer efficiency, better performance of millet/cowpea association and millet/groundnut rotation which might all result from improved nutrients and water efficiency. The issue of biotic stresses was also addressed through reducing agro-chemical inputs in controlling pests and diseases by tailoring their management components according to the regions. This work covers West Africa and South Asia and includes testing the efficiency of plant extracts, parasitoids, fungicides, genetics for both varieties and pathogens, and finally assessing changes in disease incidence linked with climate change.
In West Africa, treatment of seeds with plant extracts led to: (1) increased early suicidal germination of Striga hermonthica induced by cowpea and (2) increased yield of sorghum. Eight cowpea varieties are being screened using the same method. Biocontrol by releasing parasitoids for cowpea pod borer in Benin and Burkina Faso induced very low populations of the parasite. In South Asia, climate variability was found to affect the incidence of disease in pigeonpea (1975 to 2017) and chickpea (1972-2017). For diagnostics of fungal pathogens by the LAMP assay, primers were designed from the ITS and EF-1α genes of the chickpea pathogens R. bataticola and F. oxysporum, respectively. For each pathogen, a set of 6 primers comprising 2 outer, 2 inner and 2 loop primers were designed.
To sustainably intensify and diversify the cropping systems, a network of participatory field trials under smallholder (less than 1 ha) conditions across various livelihood contexts were established. From these, at least two options per site per country were jointly validated by the local communities and researchers in the tested crop production systems, as follows:
- Intercropping systems for maize and cowpea in combination with N application, groundnut and pigeonpea. Land equivalent ratios (LERs) of all intercrop combinations were greater than unity, indicating more efficient and productive use of environmental resources by intercrops. The economic returns from groundnut and pigeonpea were estimated at US$ 205/ha and US$ 221/ha, respectively as sole crops, compared to US$ 316/ha for intercrops. Similarly, benefit-cost ratio for intercrops was 0.50 compared to 0.40 and 0.65 achieved under sole groundnut and sole pigeonpea, respectively.
- Rotations of maize-soybean led to a 2.4-fold increase in maize yield (2.9 t/ha) and maize-cowpea rotation increased maize yield by 83% (2.2 t/ha) compared to a maize-maize combination (1.2 t/ha). This is consistent with previous reports for southern and northern Guinea savannah of Nigeria, where maize yields after soybean increased 1.2-2.3-fold compared to maize yields after maize (Sanginga et al. 2002; Yusuf et al. 2009).
- Screening of indigenous Bradyrhizobial strains on soybean with the selection of three of them displayed similar or better impact on grain yield in comparison with commercial strains. This was concurrently done with capacity development activity on AMF production involving seven MSc and one PhD student, 3 technicians, one professor, extension agents and farmers.
- Developing mixed legume tree (Chloris gayana) agro-pastoral system improved the nutritional value of fodder by increasing the crude protein content from 8.4% to 16.1-19.8%.
Besides field testing, a set of activities were implemented to develop decision support tools on:
- Distinguishing awareness from perception in climate change adaptation for policy design.
- Assessing productivity, resources use efficiency and sustainability of GLDC-based smallholder systems.
- A methodological approach for innovation adoption analysis called ‘ALS typology-based adoption analysis’.
- Designing questionnaires for surveys on farm-household livelihood typologies, innovation adoption, impacts of legume-based technological interventions on smallholder production and livelihood performance (yet gender-responsive).
To capacitate farmers in applying tested, adapted and validated options for sustainable intensification and livelihood diversification, attempts were made to determine portfolios of household activities, enterprises and management practices that materially and equitably enhance livelihoods (as defined at sub-IDO level) while minimizing negative externalities. This was done through assessing the impact of such portfolios across scales and dimensions, evaluating the trade-offs, co-designing farming systems for enhanced resilience and income, and finally by generating the information and knowledge for targeting gender and nutrition under GLDC farming systems.
For co-developed livelihood options to generate the expected change/improvement, a set of activities were devoted to identifying the criteria/indicators for use in impact assessment activities. Therefore, sustainable intensification (SI) criteria, indicators and frameworks were reviewed. Activities to improve interface among farmers, agricultural extension workers and national agricultural research for greater awareness on sustainability dimensions and complementary approaches were also undertaken. Additionally, coping strategies for both biotic and abiotic stresses and doses of various compost vs mineral fertilizers for better production and improved nutritional quality of sorghum/millet grain and fodder were assessed. The activities also included modelling frameworks (crop modelling and whole farm bio-economic modelling) to evaluate trade-offs and co-design farming systems for enhanced resilience and income. Cropping system modelling tools were assessed/validated for their integration with breeding programs as a decision-making support tool on optimization of GxExM for target population of environments. Field testing of co-designed improved farm systems on integrated crop, composting and animal feed is ongoing with Malian farmers.
Sanginga N, Okogun J, Vanlauwe B and Dashiell K. (2002). The contribution of nitrogen by promiscuous soybeans to maize based cropping in the moist savanna of Nigeria. Plant Soil 251:1–9.Yusuf AA, Iwuafor NO, Abaidoo RC, Olufajo OO and Sanginga N. (2009). Grain legume rotation benefits to maize in the northern Guinea savanna of Nigeria: fixed-nitrogen versus other rotation effects. Nutr. Cycl. Agroecosyst. 84:129–139.