ASSESSING THE POTENTIAL OF MAIZE GROWING SEASONS FOR WESTERN KENYA USING AGRO-CLIMATIC INDICES

Abstract

This paper evaluates the trends of meteorological and agrometeorological indices for Lake Victoria basin of Kenya. The criteria for selecting indices were aimed at determining the potential effects of climatic changes on agricultural water requirements and management. Identification of stations used in the study was based on the length and entirety of the data series and the homogeneous spatial coverage of the region. The daily rainfall, minimum and maximum temperature data collected at the stations were elaborated to calculate meteorological and agrometeorological indices for maize crop (staple food) in the region. Trend analyses of meteorological and agro-meteorological indices using the Mann Kendall test for the various seasons (MAM, JJA, SON and DJF) indicate that rainfall is generally decreasing over the region and temperature is increasing (tested at 0.01 and 0.05 significant levels). These climate change effects will exacerbate crop water stress through increased frequency of dry spell occurrences over the region. The AquaCrop model employed for simulating crop development and performance parameters was calibrated using the 2009 season-crop, soil and climate data collected over the region. Simulation results using AquaCrop indicate that some stations within the study area have high seasonal net irrigation requirements of 225 mm (Kisumu), and 123 mm, 150 mm, 325 mm for Eldoret, Moi University, and Narok stations respectively mainly spread in the vegetative and grain filling stages. However, most humid stations within the basin show low net irrigation requirements that could be mitigated through insitu rainfall runoff water harvesting and use of traditional field management practices. These results reveal that application of supplemental irrigation to meet the net irrigation requirements could substantially improve the yields by 1.3, 1.5, 5.7, and 5.3 tons/ha for Moi University, Eldoret, Kisumu, and Narok stations respectively. This study could enable introduction of responsive supplemental irrigation agriculture within the maize growing zones in the Lake Victoria basin region of Kenya.