Crop conversion as a strategy for enhancing water efficiency and nutrient management under climate change

Abstract

Global climate change poses significant challenges to water resource allocation and food production. This study focuses on the Fengshan River basin in northern Taiwan, where changing rainfall patterns pose a risk to water availability and ecosystem services. High water-demand crops, particularly rice and tea, face the risk of declining yields and higher nutrient runoff under the RCP2.6L and RCP8.5L scenarios. Using the Soil and Water Assessment Tool (SWAT) and entropy-weighted agro-environmental indicators, this study examines the impacts of climate change on crop water footprints and nutrient use efficiency. The results indicate that converting rice and tea fields to sweet potatoes or soybeans significantly reduces water consumption and improves nutrient efficiency, thereby enhancing overall agro-environmental sustainability under the RCP2.6L and RCP8.5L scenarios. Converting 30 % of rice and tea fields to soybeans leads to substantial improvements, reducing the blue water footprint by up to 30 % and 25 % and the green water footprint by 16 % and 33 % under RCP2.6L and RCP8.5L, respectively. Conversion to both sweet potatoes and soybeans significantly increases nutrient use efficiency, with soybeans achieving the greatest gains: nitrogen use efficiency increases by 72 % and 68 %, and phosphorus use efficiency by 197 % and 188 % under RCP2.6L and RCP8.5L, respectively. This crop conversion strategy not only helps mitigate climate change but also supports sustainable agricultural development. By providing targeted management recommendations for regions with high water demand, this study offers a framework for optimizing crop production and resource allocation in the face of global climate challenges.