Yield,Water And Nutrient Use Efficiency Of Dryland Crops In Northern China

Eryland farming plays an important role in the national food security,but the regional grain production faces the constraints of both water and soil nutrient supply.To further explore the characteristics and main driving factor of yield,water and fertilizer use of dryland crops,and identify their potential and pathways for improvement,we carried out the related research based on a large sample of field experiments carried out from 1970 to 2015 in China,and got the main conclusions are as follows:The study identified the average yield,WUE and NUE of wheat and maize during the year 1980-2015.the average yield of wheat and maize were 3902 kg/ha and 7785 kg/ha,WUE were 11.6 kg/ha.mm and 19.1 kg/ha.mm,and NUE were 30.7%and 35.1%,respectively.Since 1980s the crop yield and WUE gradually increased.In the year 2011-2015 the average yield of wheat and maize were increased by 60.2%and 54.5%,WUE were increased by 37.0%and 70.5%,respectively.Since 1980s,NUE of wheat and maize were increased firstly and then decreased,and reached the highest value in 2000s and 1990s,respectively.The yield and WUE of dryland wheat increased significantly with the increase of regional precipitation,and the yield and WUE of maize decreased significantly in tHe area of annual precipitation<350 mm regions.NUE of maize and wheat were decreased both in the relative lower and higher precipitation regions.PFP-N and PFP-P were significantly affected by water conditions,which increased significantly with the increase of regional annual precipitation.Since the year 1980,meteorological changes led to a reduction in crop yield.The increase of fertilizer input and the improvement of soil fertility led to the improvement of crop yield and WUE.However,the increase of fertilizer input resulted in the decrease of PFP and NUE of crops.The difference of crop yield,WUE and NUE in different regions was mainly affected by ET,especially for wheat.Difference in yield,WUE and NUE of wheat and maize in different regions were also caused by the imbalance use of fertilizer and soil fertility.Technical progress is an important factor for the promotion of crop yield and WUE.On an average,the contribution of technology to yield of wheat and maize were 19.1%and 18.2%,and the contribution to WUE of wheat and maize were 15.3%and 15.3%.With the increase of time and regional precipitation,contribution of technology to yield and WUE were decreased;Contribution of technology on NUE were increased with the regional precipitation increase.For single technology,plastic film mulching,straw mulching,no tillage,subsoiling,and balanced fertilization have positive effect on the yield and WUE.The potential yield of wheat and maize were 6823 kg/ha and 13149 kg/ha,respectively,and farmers attained 48.4%and 53.4%of the potential yield.The potential WUE of wheat and maize were 20.4 kg/ha.mm and 34.2 kg/ha.mm,respectively.The main causes of yield gaps were water deficit,lower fertilizer input and poor soil fertility.