Ollenburger, M. 2012. Modeling integrated soil fertility management options in Malawi under variable soil and climate conditions. Thesis, Michigan State University, East Lansing, Michigan, USA.

Citable PDF link: https://lter.kbs.msu.edu/pub/3408

Sustainable agriculture requires integrated soil fertility management, which relies to a considerable extent on the presence of legumes. On-farm participatory research in Africa has identified pigeonpea (Cajanus cajan) as a promising legume for improving fertility management in maize (Zea mays) systems. Including a long-duration legume like pigeonpea creates a tradeoff between improved soil fertility and increased water stress, and impacts of the legume on maize production will depend on soil type and rainfall regime. This effect is difficult to quantify using short-term field trials. Using the simulation model APSIM, results from on-farm research in Malawi were extended to evaluate maize-pigeonpea rotation and intercrop systems relative to continuous maize with modest (24kgN/ha) fertilizer inputs in all systems. Performance over multiple years from system establishment was evaluated in different soil types, utilizing long-term weather records from two sites. Despite trade-offs between soil fertility and moisture, maize diversified with pigeonpea produced over double the yields of continuous maize on sandy, low fertility soils, with very low risk of failure. System performance under climate change scenarios was evaluated through modification of weather station data, including changes in rainfall of +/- 10% and +/-25% and temperature increases of up to 4 °C to compare a maize-pigeonpea rotation to continuous maize at two nitrogen fertilization levels. Overall, maize yields in the rotation system were maintained under climate change scenarios, though declines were seen under some reduced rainfall scenarios. These results suggest that maize-pigeonpea systems can improve productivity in poor soils and are resilient to current and future climate variation.

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