Increasing Productivity Through Maize–Legume Intercropping in Central Kenya
Mugwe, J. N.
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Declining land productivity is a major problem facing smallholder farmers in Kenya today. This decline results from a reduction in soil fertility caused by continuous cultivation without adequate addition of external inputs. Improved agronomic measures integrating grain legumes into maize cropping systems can enhance overall system’s productivity. Trials were established in two sites in central Kenya (Mukuuni and Machang’a) to evaluate contribution of various legumes (beans, cowpea, and groundnut) and plant spacing to overall productivity of the intercropping system. The conventional spacing (a legume row alternating a cereal row) was compared to managing beneficial interactions in legume intercrop (MBILI) spacing (two legume rows alternating two cereal rows), both with and without phosphorus (P). In Mukuuni (more fertile), neither legumes nor maize responded to P application; legume yield was increased by on average 100% and maize yields more than doubled by P application in Machang’a. In Mukuuni, groundnut production was poor (<500 kg ha–1); in Machang’a, highest legume yields were obtained with cowpea. In both sites, legume yields tended to be higher in the conventional intercrop, irrespective of legume species or P application, though not consistently significant in all seasons. In contrast, in Machang’a, maize yields were generally highest when planted using MBILI spacing, provided P was applied. Without P application, higher yields were observed for maize in the conventional intercrop, but only when intercropped with beans. Maize yields were significantly higher with conventional intercrop when intercropped with groundnut, while in MBILI spacing, highest yields were observed for maize intercropped with beans. In Mukuuni, benefit–cost ratio (BCR) was higher in treatments without P and in the MBILIs. In Machang’a, BCR was not significantly different between the MBILI and the conventional intercrop. Return to labour was higher in the MBILI in Mukuuni.