Maize-grain legume intercropping for enhanced resource use efficiency and crop productivity in the Guinea savanna of northern Ghana

Smallholder farmers in the Guinea savanna agroecological zone of northern Ghana practise maize-grain legume intercropping to mitigate the risks of crop failure in sole cropping, and to safeguard household food, nutrition and income security. The productivity of maize-grain legume intercrops is influenced by soil fertility status and the spatial arrangement of the intercrop components. Although maize-grain legume intercrops have been studied in the Guinea savanna, these have been limited to distinct alternate arrangements on experimental stations. The impact of soil fertility on intercrop productivity has not been studied in the Guinea savanna despite the large variability in soil fertility status observed in farmers’ fields. Therefore, we studied the impact of different spatial arrangement of maize and grain legume intercrops (Figure 1) and soil fertility status on resource use efficiency, crop productivity and economic profitability under on-farm conditions in the southern and northern Guinea savanna agroecological zones of northern Ghana.

In Podcaster (no. 39), I presented the intercrop grain yields of cowpea and maize as affected by the spatial arrangement of the intercrops and soil fertility status while the full manuscript for publication was under preparation. The paper has now been published as:

Kermah, M., Franke, A.C., Adjei-Nsiah, S., Ahiabor, B.D.K., Abaidoo, R.C., Giller, K.E., 2017. Maize-grain legume intercropping for enhanced resource use efficiency and crop productivity in the Guinea savanna of northern Ghana. Field Crop Res. 213, 38-50.

Here I present the economic evaluation (Figure 2) of cowpea and maize intercrops and sole crops from the paper. The within-row intercrop pattern was more profitable than the distinct row arrangement. Intercropping maize and grain legumes generally led to larger net benefits compared with sole cropping of maize or a grain legume. Economic profitability of the cropping patterns declined with decreasing soil fertility. However, land equivalent ratios were greater in the low fertility fields, indicating that the intercrops used environmental resources more efficiently to produce grain yield in the low fertility fields (see paper). These results demonstrate that smallholder farmers in the Guinea savanna can intensify grain legume production by intercropping them with maize (largely the main crop) and preferably in a within-row arrangement to increase resource use efficiency, crop productivity and economic profitability.

Michael Kermah, Wageningen University & Research, The Netherlands