Effects Of Straw Returning On The Yield Of Winter Wheat And The Capacity Of Preserving Nitrogen

Guanzhong Plain is a conventional wheat-corn rotation area,and straw returning had become a routine agricultural measure.In order to provide a scientific basis for the production of winter wheat and the optimal management of nitrogen fertilizer,the test objectives were set up in the Guanzhong aregion,and the main treatments included all the maize straw return to soil(N+S)and straw removal(S),and the treatments were N0,84,168,252 and 336 kg/ha for five different nitrogen application rates.The main conclusions are as follows:1?Results of field experiment which lasted five years in Zhouzhi county showed that,the two curves of nitrogen fertilizer response function that straw returning or straw removal intersected at 153,187,99,146 and 115 kg/ha respectively.When the nitrogen fertilizer rate was lower than that of the intersection point,the yield of wheat with straw return would reduce the yield of wheat compared with straw removal.On the contrary,the yield of wheat would increase with straw return.The 5-year maximum yield was decreased 3.0%,8.4% and18.8%,14.5% and 9.1% respectively.The highest increased yield was 7.2%,5.6%,9.5%,5.8% and 7.5% respectively when the nitrogen fertilizer rate was higher than that of the intersection point.In the other experiment,the law of nitrogen fertilizer in Wugong county agreed well with that of Zhouzhi.The intersection of nitrogen and fertilizer effect curves in Wugong in 2013 and 2015 were 119 and 77 kg/ha,respectively.Compared with straw removal,straw return increased the yield of wheat was 9.5% and 8.9%.2?Straw return to soil with appropriate amount of nitrogen fertilizer can increase the nitrogen and potassium contents of different organs of winter wheat,phosphorus content of stem and leaf and glume.Straw returning to the soil can increase the uptake of nitrogen,phosphorus and potassium in the aboveground of winter wheat.The amount of potassium uptake was increased 7.2%~13.7% in Zhouzhi county,and was increased 12.2%~26.0% in Wugong county.3?The content of soil organic matter with straw return is higher than that of straw removal.The increase rate of organic matter was 4.4%,6.6%,4.2%,7.0% and 6.8%,respectively from 2012 to 2016.The highest growth rate treatment was N168,N0,N84,N84 and N0,respectively.The results showed that the soil organic matter was the same as that of straw,N84 and N0,the increase was 15.9%,10.7%,11.0%,22.5% and 7.0%.4?With the increase of nitrogen application rate,the accumulation of nitrate nitrogen in the soil will increase after harvest,straw return had obvious effect on preserving nitrogen.From the average value,the corn stalks are beneficial to the accumulation of nitrate nitrogen in the winter wheat after the harvest,and the straw return ratio in 2012~2016.The increase of nitrate accumulation in the soil was 25.1,8.9,64.5,65.8 and 7.5 kg/ha,respectively.The increase rates were 25.4%,3.4%,13.5%,24.0% and 1.7%,respectively.During the period from 2013 to 2016,the accumulation of NO3-N in the soil pretreated with N0 was increased year by year,and the 2-year straw The accumulation of NO3-N in the soil increased by 117.8kg/ha and increased by 175.3%.The accumulation of NO3-N was increased by 108.8 kg/ha,or161.0%.