Diversification and intensification are synergistic: field trials evidence from nitrogen-managed maize–cowpea intercropping in Malawi

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dc.creatorOmondi, J.O.
dc.creatorSimwaka, P.
dc.creatorKamwana, F.
dc.creatorSiyeni, D.
dc.creatorSika, G.
dc.creatorKadwala, P.
dc.creatorMsukwa, W.
dc.creatorKyei-Boahen, S.
dc.creatorAkinwale, G.
dc.creatorAlene, A.
dc.date2026
dc.date2026-05-20T12:16:26Z
dc.date.accessioned2026-06-27T16:05:27Z
dc.descriptionContext Sustaining maize productivity on nitrogen (N)-depleted soils while enhancing system efficiency and profitability remains a central challenge in sub-Saharan Africa. Maize–legume intercropping can improve soil health and land-use efficiency, yet its performance under intensified mineral N management and rhizobial inoculation remains insufficiently quantified. Objective This study evaluated the productivity, physiological responses, land-use efficiency, farmer preference and profitability of maize–cowpea intercropping under contrasting fertilizer-applied N rates and cowpea inoculation across agro-ecological zones in Malawi. Methods Maize-based trials were conducted at two research stations during 2020/2021 and 2021/2022 seasons, followed by farmer-managed validation across seven districts during 2022/2023 and 2023/2024 seasons. Treatments combined maize N rates (0, 100 and 200 kg N ha⁻¹) with cowpea N fertilization or rhizobia inoculation. Grain yield, chlorophyll content (SPAD), nodulation traits, and leaf nutrient status were measured. Land equivalent ratio (LER), mixed-model analysis, relative-importance analysis and structural equation modelling were used to quantify treatment effects and yield pathways; farmer participatory evaluation and partial budgeting assessed acceptability and profitability. Results Maize yield increased strongly with fertilizer-applied N and improved cowpea management. On-station, the zero-N maize control averaged 4.4 t ha−1 at Chitala and 0.45 t ha−1 at Makoka, whereas the best integrated treatment (200 kg N ha−1 maize + inoculated cowpea) yielded 12.0 and 13.7 t ha−1, respectively. On-farm, the same treatment reached 4.7–7.6 t ha−1 in high-performing districts during 2023/2024, compared with < 2 t ha−1 for zero-N maize in several sites. Cowpea yield and nodulation were more strongly associated with inoculation and leaf N status than with direct mineral N addition, although high maize N reduced nodule dry weight. LER exceeded 1.0 in 80% of intercropping treatments and 1.2 in 70% of cases. Integrated high-N + inoculation treatments generated the highest farmer preference and increased net returns by 2–5 folds relative to low-inputs systems. Conclusions and Implications Diversification and intensification function synergistically when mineral N management is integrated with functional legumes. Moderate-to-high N rates combined with inoculation offer strong performance, but trade-offs related to nitrogen-use efficiency and risk must be considered. System-based N recommendations that incorporate rhizobial inoculation within maize–cowpea intercropping can enhance productivity, nitrogen-use efficiency, land-use efficiency, and profitability. This approach provides a scalable resilience pathway for sustainable intensification in sub-Saharan Africa.
dc.identifierhttps://hdl.handle.net/10568/183008
dc.identifier.urihttp://hdl.handle.net/123456789/122222
dc.languageen
dc.rightsLimited Access
dc.sourceOmondi, J.O., Simwaka, P., Kamwana, F., Siyeni, D., Sika, G., Kadwala, P. ... & Alene, A. (2026). Diversification and intensification are synergistic: field trials evidence from nitrogen-managed maize–cowpea intercropping in Malawi. Field Crops Research, 345, 110549, 1-12.
dc.subjectcropping systems
dc.subjectlegumes
dc.subjectinoculation
dc.subjectsustainable intensification
dc.subjectsub-saharan africa
dc.subjectmaize
dc.titleDiversification and intensification are synergistic: field trials evidence from nitrogen-managed maize–cowpea intercropping in Malawi
dc.typeJournal Article

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Instituto Internacional de Agricultura Tropical (IITA)