Simulation of yield and quality of malting barley

A computer simulation model was developed to determine the likely response of grain yield and quality of malting barley crops to differing availability of water or nitrogen (N) and differing soil and climatic conditions. The model was validated for New Zealand conditions by comparing the results of model simulations with data from malting barley crops grown in the Manawatu. Simulations were then performed to determine the best water and N management strategies for producing quality grain for malting (low N concentration and large grain size) as well as minimising the production risks and variability across seasons. Predictions were obtained for plant development, biomass production, and crop quality variables. Without irrigation there was a high risk of producing high grain N concentration, and therefore poor malting quality, irrespective of N management. With irrigation, the probability of producing grain with less than 2% N was greatly increased. Good quality grain could be produced even on high fertility sites or with high N inputs provided there was enough water to sustain growth processes at a near-optimal level. Additional key words: irrigation, nitrogen, modelling, response suifaces