Trends of rainfed and irrigated crop yield influenced more by increased cultivated area than drought in Iran
摘要
Over recent decades, climate change has intensified drought, with pronounced effects on agriculture in arid and semi-arid regions. Here, we quantified the impact of drought and cultivated area on crop yield (wheat and barley) trends in Iran from 1995 to 2022. We moreover analyzed changes in crop yields due to drought and total cultivated area in irrigated and rainfed systems. To do this, we used data on annual crop yields, cultivated area, the Standardized Precipitation Evapotranspiration Index (SPEI) with the Mann–Kendall trend test, and a non-linear boosted regression tree model. Our results show that total cultivated area increased by up to 40% in irrigated systems and 38% in rainfed systems, and had a stronger influence on crop yields trends (i.e., explaining 71% to 87%) than drought (i.e., explaining 12% to 29%) across both rainfed and irrigated systems. Consequently, overall crop yields increased by 0.26 (t ha⁻1 yr⁻1) in irrigated systems and 0.075 (t ha⁻1 yr⁻1) in rainfed systems despite reductions from drought of 12–29%. Furthermore, our results demonstrate that rainfed systems are more vulnerable to drought than irrigated systems, especially for wheat. Our findings underscore the vulnerability of rainfed agriculture to climate stressors such as drought and highlight the urgent need for sustainable water management strategies, investments in drought-resistant crops, and improved irrigation efficiency to mitigate future agricultural losses and ensure agricultural sustainability.