Soy-Maize Crop Rotations in Sub-Saharan Africa: A Literature Review

Abstract

Empirical evidence shows complementarity between maize and soybean as a sustained agricultural system across North and South America as well as Eastern Europe. The potential application to sub-Saharan Africa motivates this literature review. Maize is one of the most important crops on the African subcontinent, accounting for over half of daily caloric intake in some regions. However, continuous cropping of maize has led to extensive degradation of soil and decrease in crop productivity and endangers household food and nutritional security. The cultivation of soybean holds great promise in improving agricultural systems in sub-Saharan Africa. Introducing soy into rotation with maize is a method to diversify diets, better nutritional status, reduce abiotic and biotic stresses, and improve soil fertility, while enhancing crop productivity and generating more income for farmers. However, limited access to extension services and other sources of technical support constrains adoption of the more complex rotation cropping system involving a new crop, soybean. Rotating soybean with maize too challenges farmers as there is not a specific prescription that can guide farmers operating across Africa’s diverse agroecological environments. Finally, soybean is an input-intensive crop requiring significant investment at planting, which may not allow small holders with limited resources and no access to credit.

Long‐term soybean–maize rotation experiments in cereal‐based farming systems at Bako, Western Ethiopia

“…This is constant with the prior study, which shows that a soybean–maize rotation improves yield (Boomsma et al, 2010; Franke et al, 2018; Lauer et al, 1997; Nyambo et al, 2020; Uzoh et al, 2019). When compared to cereals grown continuously, soybean–maize rotations boost SSA cereal yields by 0.49 tons ha −1 or more in fields planted following a legume (Acevedo‐Siaca & Goldsmith, 2020). Furthermore, after 4 years of trial, soybean–maize rotations may preserve high levels of maize productivity when compared to continuous maize farming (Kanton et al, 2017), making this approach very useful and sustainable over time, where maize production is a key agricultural practice in SSA.…”

“…Maize is a key food security and vital crop (Falconnier et al, 2023) accounting for more than half of daily calorie intake in some parts of the African continent (Acevedo‐Siaca & Goldsmith, 2020), with more farmers relying on maize production in eastern Africa. However, the mono‐cropping of maize has resulted in substantial soil deterioration and decreased soil productivity.…”

“…However, the mono‐cropping of maize has resulted in substantial soil deterioration and decreased soil productivity. The utilization of soybean–maize rotations in the tropics has several agronomic benefits, including increased soil fertility, less biotic pressure, and increased maize and soybean yields (Acevedo‐Siaca & Goldsmith, 2020; Franke et al, 2018; Yuan et al, 2022). Maize is the main staple food crop in rural Ethiopia, notably in the western and southwestern parts of the country (Yami et al, 2020).…”

Lime, inoculum, and phosphorous input supplementation under rain-fed soybean in Ghana's northern savannas

“…However, the benefits of lime are not limited to economic gains only but residual and non-economic benefits that sustain farmers (Asodina et al, 2020). The long-term benefits of lime include the residual benefits of enhancing seedling development, nutrient availability, and improving soil pH for the sustenance of smallholder agriculture (Acevedo-Siaca and Goldsmith, 2020;Dabesa and Tana, 2021). Lime is known to have a long-term benefit; hence the yearly evaluation may not reflect the profitability and economic benefits desired associated with the cost of the lime product.…”