Exploration and assessment of innovative farming options for sustainable improvement of soybean and maize production in Benin
(2025)
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- Nitrogen (N) and phosphorus (P) are essential nutrients for the growth and productivity of soybean and maize. However, these elements are often deficient in most soils in Sub-Saharan Africa, particularly in Benin. Sustainable agricultural practices (SAPs) including fertilizer microdosing (FM), seed inoculation with efficient symbiotic microorganisms, and intercropping systems could reduce the production cost and enhance the nutrient availability in soil for crop productivity, while minimizing environmental and health impacts of agriculture. Rhizobia and arbuscular mycorrhizal fungi (AMF) are widely known to contribute to fulfil the N and P need of soybean in nutrient deficient soils. The general objective of this study was therefore to explore and assess innovative farming practices for the sustainable enhancement of soybean and maize production in Benin. For this purpose, we combined three different approaches: (1) a diagnostic survey on the agricultural practices adopted by soybean and maize producers, (2) a study on the diversity of rhizobia associated with soybean roots, and (3) the assessment of the effects of double inoculation with AMF (Rhizophagus irregularis MUCL 41833) and Rhizobium etli (BANIL1B). combined with FM in two different row-configurations of soybean-maize intercropping systems. A survey conducted on 343 soybean and maize producers in three agroecological zones (AEZs: II, III, and V), revealed that farmers of AEZ V adopted SAPs, although moderately, while intensive farming was more practiced in the AEZs II and III. Seed inoculation was the less adopted SAP (13%) among those evaluated. The main constraints encountered by farmers included decreasing soil fertility, drought, and high costs of agricultural inputs. Based on these constraints, it seemed that the adoption of SAPs was more driven by economic or climatic constraints than by a sake of environmental sustainability. Regarding indigenous rhizobia screening, soybean roots were associated with Rhizobium and Bradyrhizobium species with high variability in symbiotic effectiveness and response to abiotic stress factors, with strains BANIL1b, BANIL2b, and NDTA1a exhibiting significantly higher symbiotic effectiveness compared to the other strains. Additionally, the results showed that the available N, P and C contents in the soil were the main soil properties influencing the diversity of rhizobial communities. Field trials using isolated Rhizobium strain (R. Etli_BANIL1b) with AMF combined with P-FM application on soybean showed positive and significant results. FM significantly increased soybean and maize growth parameters and yields compared to unfertilized treatment. Double inoculation with AMF and Rhizobium without P-FM significantly increased soybean grain yield by 140% and 59% relative to single inoculation with R. irregularis and R. etli., respectively. A similar trend was recorded with both soybean-maize intercropping systems assessed, where total land equivalence ratios (LER) for both intercropping systems were > 1, with the 2-row configurations recording the highest LER (1.40) compared to 1-row configuration (1.21). Species complementarity effect on grain yields contributed more to the net effect as shown by minimal or negative values of selective effect. Overall, we concluded that the 2-row configuration of each crop ²with reduced fertilizer rate combined with double inoculation, could optimize interspecific interactions and improve system productivity of soybean-maize intercropping. This research offers a foundation for adopting innovative farming practices aimed at sustainably enhancing soybean and maize productivity and resilience in nutrient-deficient soils in Benin. Participatory experimentation involving producers is required to facilitate the dissemination and adoption of these significant findings.
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Sinhouenon, B. G. (2025). Exploration and assessment of innovative farming options for sustainable improvement of soybean and maize production in Benin. https://hdl.handle.net/2078.5/274816