Soil with high plant available water capacity can mitigate the risk of wheat growth under drought conditions in southeastern Australia

Abstract

The soil's variable capacity to store water, known as plant available water capacity (PAWC), may mitigate the adverse effects of drought on crop yields. Nonetheless, the extent to which this mitigation can decrease the probability of crop productivity loss under various drought scenarios, as well as the specific thresholds at which drought begins to restrict crop growth, remains unclear. In this study, we used the Agricultural Production System sIMulator (APSIM) model to simulate wheat growth and plant available water for 10 different soils with different PAWCs in the New South Wales (NSW) wheat belt, southeastern Australia. By combining copula functions, we estimated the probability of wheat biomass loss under various drought scenarios. We found that simulated wheat yield and biomass were elevated in areas characterized by soils with high PAWC. The probability of biomass loss decreased by 20 -50% as the PAWC of soil increased under various drought conditions. Moreover, the drought mitigation capacity of soils with higher PAWC demonstrated a more pronounced effect in high-rainfall areas compared to arid regions. We identified that the drought mitigation effects became weak when the PAWC threshold exceeded 207mm. Adopting sustainable farming strategies is required to enhance soil water retention in the high-rainfall regions of the NSW wheat belt, thereby minimizing the risk of crop biomass losses. The framework presented in this study is intended to offer valuable guidance to stakeholders seeking to improve management strategies for sustaining wheat production in dryland agricultural regions.