Yields of staple crops such as maize (Zea mays), rice (Oryza sativa) and wheat (Triticum aestivum) have stagnated in many parts of Sub Saharan Africa resulting in large yield gaps which have exacerbated food insecurity.

A multi-disciplinary approach comprising of different data collection; soil sampling, field measurements, household surveys, on farm experiments, satellite imagery) and analysis methods; Generalized Linear Mixed Model (GLMM), Classification and Regression Tree analysis (CART), Factor Analysis (FA), Linear Mixed Effects Model analysis (LMER) and Spatial Analysis Techniques was used to investigate causes of yield gaps in Mukuyu-Kakamega and Shikomoli-Vihiga of Western Kenya.

The average maize yield and yield gaps for Mukuyu were 3.8 t ha-1 and 1.8 t ha-1 while for Shikomoli they were 2.7 t ha-1 and 2.6 ha-1. Factors influencing yield gaps included; education, age, membership to groups, access to markets, family labour, gender, credit facility, maize variety, crop residue, quantity of organic and inorganic fertilizer use, maize density, chlorophyll values, maize height, and depth to compact layer which were consistent across the study sites. Weed cover at early stages and maize density at late stages were the most limiting factors in maize production in Mukuyu and Shikomoli, respectively.

Large yield gaps > 30% exist on smallholder, and policy measures aimed at improving soil fertility, market accessibility, relaying agricultural information and encouraging family involvement in agronomic activities are needed to improve yields. Agro-ecology and field specific measures focused on improving particular soil nutrient types and levels, weed management and plant density are also required.

College Unit
Faculty of Agriculture