Consequences of variable rainfall on farming outcomes for dryland maize farmers

Abstract:

Smallholder farmers who plant with limited resources and are highly reliant on a stable climate need to carefully select management strategies that are well suited for local environmental conditions. Maize varieties once suitable for a particular climate can lead to heavy crop loss if rainfall seasonality changes—as is experienced by many smallholder farmers, particularly in east Africa. To better understand the impact of cultivar choice on crop growth, we present a new ecohydrological model. We apply the model to analyze the growing conditions of smallholder farmers in central Kenya, which is a drought-prone and semiarid region with spatially heterogeneous rainfall. We simulated seasonal rainfall dynamics using a 40-year daily rainfall data set and modeled stochastic seasonal water availability for cultivars with different maturation lengths. In agreement with past studies, we find that storms are becoming more intense and less frequent in historical rain gauge records. Maize is prone to water deficit in the later part of the season when crop water requirements are highest and we showcase the susceptibility of maize to total crop failure in systems with highly variable rainfall. In light of shifting rainfall conditions, we show that the historical probability of crop failures was previously lower and crop failures are becoming more likely. We find that increasingly variable rainfall conditions, namely the distribution of rainfall during the season, have important consequences on farming outcomes for dryland maize farmers.