Responses of Wheat Yield under Different Fertilization Treatments to Climate Change Based on a 35-Year In Situ Experiment

Abstract

Fertilization, as one of many important field management practices, can increase crop yields. However, whether different levels of fertilization will affect the response of wheat yields to inter-annual climate variations and long-term climate trends is not clear. In this study, 35-year wheat yields were used to investigate the responses of wheat yield to inter-annual climate variations and long-term climate trends under different fertilization treatments. The first difference method was used to de-trend wheat yields and climate variables and stepwise regression analysis was used to quantify the yield–climate relationship. The experimental design consisted of a control treatment (CK without fertilization) and three fertilizer treatments: nitrogen, phosphorus, and manure (NPM with 120 kg ha−1 N, 26.2 kg ha−1 P, and 75 t ha−1 manure), nitrogen and phosphorus (NP with 120 kg ha−1 N and 26.2 kg ha−1 P), and manure (M with 75 t ha−1 manure). Compared to the CK treatment, the NPM, NP, and M treatments increased wheat yield by an average of 201.9, 161.7, and 130.6% and increased yield inter-annual variability by an average of 191.2, 149.3, and 144.2%, respectively, during the study period (1985–2020). Inter-annual climate fluctuations in the study area explained 45, 38, 27, and 29% of wheat yield variations and 35-year climatic trends contributed to wheat yield decreases of 0.3, 0.7, 1.6, and 1.8% for the NPM, NP, M, and CK treatments, respectively. The results show the impact of inter-annual climate fluctuations on yield increases with the increasing level of fertilization, while the effect of long-term climate trends on yield decreases with the increasing level of fertilization.