Spatio-temporal patterns of winter wheat yield potential and yield gap during the past three decades in North China

To develop strategies for sustainable intensification of agricultural production, it is necessary to obtain precise and spatially explicit knowledge of crop potential and yield gap at a large scale. In this study, we estimated the yield potential for winter wheat by county during the period of 1981-2008 in North China using an ensemble simulation of a well validated large-scale crop model, MCWLA-Wheat, for each 0.5° × 0.5° grid. An ensemble simulation was used to better represent the heterogeneous conditions in climate, soil and cultivars over a large area. The spatio-temporal patterns of winter wheat actual yield, yield potential and yield gap were evaluated according to the simulation results. We found that more than 90% of counties had experienced an overall increase in wheat yield. However, 30.1% of counties have already experienced yield stagnation. The mean yield potential ranged generally from approximately 5000 to 8000 kg/ha. The yield potential under water-limited conditions showed considerably smaller values, ranging from about 2000 to 5000 kg/ha. Yield gaps in about 62% of counties were generally lower than 40% of potential yields, indicating a relatively small potential for yield improvement. During the study period, yield potential decreased in most counties because of a significant increase in temperature and decrease in solar radiation. In contrast, the increase of yield potential in the west and southeast areas could be attributed to the increase of solar radiation during the growing season. Overall, yield gap in the past decades showed a substantial decrease due to the changing pattern of yield potential and the rapid increase of actual yield, especially in the North China Plain, with a rate of 1-3% per year. These patterns imply a shrinking of space for further yield improvement. Our results highlight the necessity of applying advanced management technologies to realize a high yield, as well as adopting technical progress and policy support to overcome the yield bottleneck. Moreover, breeding climate-resilient cultivars to further increase yield potential should be of equal importance.