Subsistence input rates limit farming systems’ potential in a longterm on-farm trial in Central Kenya

In Sub-Saharan Africa, where most farmers are subsistent, crop productivity has gradually declined mainly due to a decrease in soil fertility and erratic rainfall. Therefore, there is a need to evaluate the long-term response of common farming systems to varied seasonal conditions under ideal farm conditions. We tested the performance of Organic, Conventional, and Integrated farming systems in farmers` fields under low-input rates in a maize-based 3-year crop rotation from 2012 to 2023. There were seasonal variations in crop yields with occasional crop failure, especially with legumes. This was mainly occasioned by damping off during early growth stages due to high rainfall amounts, and flower abortion during reproductive stages caused by dry spells, ultimately resulting in yield distress. Maize grain and potato tuber yields were significantly higher ( p < 0.01) in Integrated compared to Organic and Conventional farming systems. On the other hand, bean grain yield was significantly higher (< 0.01) in the Organic compared to the other farming systems in all the seasons. The Organic farming system had significantly higher pH, zinc, phosphorus, and calcium ( p < 0.01) at the end of the experimental period. Overall, none of the farming systems attained the yield potential of the test crops. Moreover, all the farming systems did not enhance soil properties. Therefore, subsistence input levels of all farming systems do not suffice to sustain soil health and crop productivity, especially under rainfed conditions.