Abstract:

【Objective】By analyzing the spatial and temporal changes of winter wheat yield and nitrogen management differences in North China Plain, the evolution of winter wheat yield, efficiency and environmental impacts in the five provinces of North China Plain from 2005 to 2014 were clarified. 【Method】 Based on the farmer household survey data in 2005-2014, the time and space variation of yield, yield gap and nitrogen management differences of winter wheat in the five provinces of North China Plain was analyzed. In addition, the evaluation system of nitrogen sustainable management in North China was designed from three dimensions of food security resource efficiency and environmental protection, and the current status of nitrogen management in the five provinces of North China Plain was evaluated. 【Result】(1) The average of winter wheat yield in the five provinces of North China Plain from 2005 to 2014 was 6.5 t·hm ^-2, showing an increasing trend year by year, with an overall increase of 7% in ten years. The ten-year average of yield from high to low was Henan, Northern Anhui, Shandong, Hebei, Northern Jiangsu. The average yield gap of North China Plain in the past ten years was 1.4 t·hm ^-2, which was a downward trend. The decline in the decade was as high as 47%. The average of yield gap from high to low, it was Shandong, Hebei, Northern Jiangsu, Henan, Northern Anhui. The yield gap of Northern Anhui had the largest decline, which was the smallest; the difference of the yield gap in Shandong Province was large, showing a trend higher in the east than in the west. (2) The average nitrogen application in North China Plain was 226 kg·hm ^-2, which was increasing year by year except for Northern Jiangsu. The average growth rate was 3% in ten years. And the order of Northern Jiangsu＞Hebei＞Shandong＞Northern Anhui＞Henan was maintained. The nitrogen application in the same province had changed little and the inter-provincial difference was obvious. (3) The average nitrogen use efficiency (NUE) in North China Plain was 44%, from high to low was Henan, Northern Anhui, Shandong, Hebei, Northern Jiangsu. The spatial variation of NUE was large; while the NUE in areas with high nitrogen application was low. (4) The mean value of nitrogen surplus was 165 kg·hm ^-2. The order of Northern Jiangsu＞Hebei＞Shandong＞Henan＞Northern Anhui was maintained, which was similar to the regional distribution trend of nitrogen application. (5) Based on comprehensive evaluation of the North China Plain during 2005-2014, the number of counties that met the safety boundary of the sustainable management evaluation system for nitrogen was only 2% of the total. The nitrogen surplus and yield mean of the region were divided into four zones. The mean value of Henan was in the high yield area with low nitrogen surplus. The mean values of Shandong and Northern Anhui were in low nitrogen surplus and low yield zone. Hebei and Northern Jiangsu were in high surplus and low production zone. 【Conclusion】 During 2005-2014, the yield of winter wheat in North China Plain increased year by year, and the yield gap decreased year by year. At the same time, the input of nitrogen application increased, the nitrogen surplus was too high, and the nitrogen use efficiency was low. The nitrogen management in Henan was relatively reasonable, while nitrogen surplus in Northern Anhui and Shandong were low, and there were a large space for production improvement. High nitrogen fertilizer input in Hebei and Northern Jiangsu led to high environmental pressure of low nitrogen use efficiency, which would be the key areas for nitrogen management in North China Plain in the future.

Key words: winter wheat, North China Plain, nitrogen fertilizer, grain yield, nitrogen use efficiency, nitrogen surplus, spatiotemporal variation