On the relation between soil water holding capacity and dryland crop productivity

Abstract

Abstract Plant available water holding capacity (PAWC) influences the efficiency of rainfall used by crops and consequently crop productivity in dryland cropping systems. However, how soil PAWC interacts with rainfall to determine crop yield has not been quantified systematically. In this study, we used an agricultural production systems model (APSIM) and wheat as an example to quantify crop growth and yield in response to a wide range of soil PAWCs. Results show that wheat yield increased with soil PAWCs following a negative exponential curve. There is a critical PAWC above which PAWC has no impact. A summary model incorporating the impact of soil PAWC, annual rainfall and the fraction of rainfall during growing season together could explain over 95% variations in long-term averaged wheat yield. The results and the summary model provide the scientific basis to systematically explain crop yield variation in response to soil PAWC change across contrasting climates.