Fertilizer response to climate change: Evidence from corn production in China.

Corn is the third most cultivated food crop in the world, and climate change has important effects on corn production and food security. China is the top user of chemical fertilizer in the world, and analyzing how to effectively manage fertilizer application in such a developing country with resource constraints is crucial. We present empirical evidence from China to demonstrate the nonlinear impact of temperature on fertilizer usage in corn production based on a panel dataset that shows 2297 corn-growing counties during 1998-2016. Our findings indicate that fertilizer usage barely changes with increasing temperatures that are below 28 °C; however, exposure to temperatures above 28 °C leads to a sharp increase in fertilizer use. The increase in temperatures in the sample period implies that fertilizer usage per hectare for corn increased by 1.5 kg. Summer corn fertilizer application in the Yellow-Huai River Valley is more sensitive to warming than in the North region. Moreover, nitrogen, phosphorus, and potassium fertilizers have different temperature thresholds of 32 °C, 20 °C, and 20 °C, respectively, that cause significant changes.