Climate-adapted companion cropping increases agricultural productivity in East Africa

Production of cereals, the main staple and cash crops for millions of farmers in sub-Saharan Africa (SSA) is severely constrained by parasitic striga weed Striga hermonthica, stemborers and poor soil fertility. A companion cropping system known as 'push-pull' overcomes these constraints while providing additional soil fertility and forage grass benefits to smallholder farmers. To ensure the technology's long-term sustainability in view of the current and further potential aridification as a consequence of climate change, drought-tolerant crops, Brachiaria cv mulato (border crop) and greenleaf desmodium (intercrop), have been identified and incorporated into a 'climate-adapted push-pull'. The aims of the current study were to evaluate effectiveness of the new system (i) in integrated control of striga and stemborer pests and (ii) in improving maize grain yields, and to evaluate farmers' perceptions of the technology to assess potential for further adoption. 395 farmers who had adopted the technology in drier areas of Kenya, Uganda and Tanzania were randomly selected for the study. Each farmer had a set of two plots, a climate-adapted push-pull and a maize monocrop. Seasonal data were collected in each plot on the number of emerged striga plants, percentage of maize plants damaged by stemborers, plant height and grain yields. Similarly, farmers' perceptions of the benefits of the technology were assessed using a semi-structured questionnaire. There were highly significant reductions in striga and stemborer damage to maize plants in the climate-adapted push-pull compared to the maize monocrop plots: striga levels were 18 times lower and stemborer levels were 6 times lower. Similarly, maize plant height and grain yields were significantly higher. Mean yields were 2.5 times higher in companion planting plots. Farmers rated the climate-adapted push-pull significantly superior in reducing striga infestation and stemborer damage rates, and in improving soil fertility and maize grain yields. These results demonstrate that the technology is effective in controlling both weeds and pests with concomitant yield increases under farmers' conditions. It thus provides an opportunity to improve food security, stimulate economic growth, and alleviate poverty in the region while making agriculture more resilient to climate change.