Modelling Nutrient Dynamics and Maize Yield sunder Different Cropping Systems and Organic Amendments Using APSI Min Central Kenya

Abstract

A simulation study was carried out using APSIM model to assess the maize yield and soil nutrients to changes in temperatures and rainfall in Kabete and Kiserian areas of central Kenya. To obtain data for model calibration and validation, on-station (Kabete) and on-farm experiments (Kiserian) were set out during the short rain season of 2013. The experimental design was a randomized complete block (RCBD) with a split-plot arrangement where the main plots were three cropping systems; monocropping, intercropping and crop rotation and the split plots were farmyard manure (FYM) and Minjingu Rock Phosphate (MRP), and a control. The effect of the changesin rainfalland temperature on maize yields was considered, i.e. current temperature combinations in accordance to the International Panel on Climate Change projections.The model performed better for Kabete (ME=0.6) than Kiserian (ME=0.9). Simulations of crop rotations correlated most (R2=0.48) with observed results at Kabete and Kiserian. Simulations of the intercrops correlated favourable with coefficientofdetermination(R2)valuesof>0.4showingareasonablerelationshipbetweenobserved and simulated values. However, mono-crop simulation varied highly from observed yields (R2<0.3). TheAPSIMsimulatedmatched well withtheobserveddata in thetrial;rootmeansstandarderror