Determination of the Best Planting Season for Green Gram in Kitui County - Kenya, Using Analytic Hierarchy Process

Abstract

Green gram has recently become an important crop in Kitui County because of its high economic returns and short growing season. The purpose of this study was to analyze the spatial variation of rainfall and temperature, and its effects on the potential for green gram production. The Analytical Hierarchy Process (AHP) decision-making tool was used to determine the perceived weights or influence that rainfall and temperature have on green gram production using information from literature and expert opinions. The seasonal rainfall totals and seasonal mean temperature for the ‘long rains’ (March – May; MAM) and ‘short rains’ (October – December; OND), were calculated from Worldclim data while the rainfall and temperature requirements for green gram were determined and grouped into four classes based on FAO (1976) guidelines. Using this information the green gram growing potentials were determined and corresponding maps generated. Results of the weighted overlay of rainfall and temperature show that during MAM 4.9%, 33.9% and 61.3% are highly, moderately and marginally, suitable for green gram production, respectively. During OND, two classes emerge with 75.6% and 24.4% being highly and marginally suitable, respectively. Due to the higher potential in OND the government should adequately prepare to ensure they maximize on the good environmental conditions.