Effects of straw and plastic film mulching on soil nitrogen fractions and corn yield in the Weibei rainfed highland

Mulching with straw and plastic film has been widely used to conserve soil water,increase temperatures,and increase crop yield in the dryland areas.However,its influence on soil nitrogen fractions is not well known.Based on a 7year field experiment in the Weibei rainfed highland area of Loess Plateau of China,we compared the long-term effects of straw and plastic mulching on soil total nitrogen（STN）,particulate organic nitrogen（PON）,potential nitrogen mineralization（PNM）,microbial biomass nitrogen（MBN）,and mineral nitrogen（NO3--N and NH4+-N）as well as on corn yield.Three treatments were included:no mulching,straw mulching,and plastic film mulching.Averaged across 5-7 years,the concentrations of STN,PON,PNM,MBN,and NO3--N at 0-10 cm depth increased by 13.11%,64.29%,17.51%,16.94%,and 55.37%,and the STN,PON,MBN,and NO3--N concentrations at 10-20 cm increased by 5.93%,33.33%,15.78%,and 27.57% with straw than with no mulching（P