Characterizing spatial and temporal variability of crop yield caused by climate and irrigation in the North China Plain

Grain yields of wheat and maize were obtained from national statistics and simulated with an agricultural system model to investigate the effects of historical climate variability and irrigation on crop yield in the North China Plain (NCP). Both observed and simulated yields showed large temporal and spatial variability due to variations in climate and irrigation supply. Wheat yield under full irrigation (FI) was 8?t?ha^?1 or higher in 80% of seasons in the north, it ranged from 7 to 10?t?ha^?1 in 90% of seasons in central NCP, and less than 9?t?ha^?1 in 85% of seasons in the south. Reduced irrigation resulted in increased crop yield variability. Wheat yield under supplemental irrigation, i.e., to meet only 50% of irrigation water requirement supplemental irrigation (SI)] ranged from 2.7 to 8.8?t?ha^?1 with the maximum frequency of seasons having the range of 4?C6?t?ha^?1 in the north, 4?C7?t?ha^?1 in central NCP, and 5?C8?t?ha^?1 in the south. Wheat yield under no irrigation (NI) was lower than 1?t?ha^?1 in about 50% of seasons. Considering the NCP as a whole, simulated maize yield under FI ranged from 3.9 to 11.8?t?ha^?1 with similar frequency distribution in the range of 6?C11.8?t?ha^?1 with the interval of 2?t?ha^?1. It ranged from 0 to 11.8?t?ha^?1, uniformly distributed into the range of 4?C10?t?ha^?1 under SI, and NI. The results give an insight into the levels of regional crop production affected by climate and water management strategies.