Sabri Joshua Lado, Japhet Onyando, Dr. Anthony Karanja
Abstract: This experiment was conducted from June to September, September to December 2016 at the Agricultural Engineering Department/ demonstration farm/ Egerton University Nakuru Kenya. The objective of the study was to calibrate validate aqua crop model for full and deficit irrigation of French bean. The modified FAO Peneman Montieth method was used to calculate ETo by adapting ETo calculator, Crop coefficient was used to calculate evapotranspiration ETc, the water application levels was 100 % of evapotranspiration (ETc), 80 % ETc, 60 %ETc, and 40 %ETc, based on these irrigation levels. The experiment was laid out in Randomized Complete Block Design (RCBD) with four treatments and three replications. Data collection during the experiment was including weather data (Temperature, wind speed, relative humidity and rainfall) and other variables (soil moisture content, irrigation depth) as well as crop data (crop height, number of branches, leaf area index, biomass and final yield). Highest yield was found in treatment 100 % ETc (9.180 t/h) and the lowest yield was found in treatment one 40 % ETc (3.9 t/ha) the deficit irrigation was observed throughout the season except crop establishment (initial stage). The performance of the model was efficient in simulation of final biomass, pod yield and canopy cover but it performed less in simulation biomass and pod yield of the treatments less than 60 % ETc ( under the severe water stress throughout the season). Aqua Crop model require less inputs and easy to use and its good degree of simulation and accuracy make it useful decision making tool for investigation deficit irrigation and French bean growth in the region.
Keywords: Deficit irrigation, French bean, Aqua Crop, Calibration, Yields, Water requirement