Effect Of Fertilization On Farmland Nitrogen Loss And Balance In Hetao Irrigation Area

The irrational fertigation and irrigation in Hetao Irrigation Area resulted in a large amount of nitrogen loss and aggravating agricultural non-point source pollution.In recent years,the addition of soil conditioner has become an important means to reduce nitrogen loss of farmland and to control the pollution of agricultural surface source.In this experiment,we set up biochar,bentonite and polyacrylamide treatments on the basis of optimized fertilization.We systematically studied soil NH₃-N volatilization,N₂O-N emission and N leaching in 2-year maize and 1-year wheat rotation system and established farmland nitrogen balance bill in Hetao Irrigation District.The results show:1.Adding biochar and bentonite could significantly increase the content of soil organic matter.After harvest,the content of soil organic matter increased by 11.54%,14.73%.Application of biochar,bentonite and polyacrylamide significantly increased soil nitrate nitrogen content by 22.05%,16.89%and 13.91%respectively compared with the control.Long-term application of biochar significantly increased soil pH,an increase of 0.42 units in three years.2.Compared with the control,the average yield of crop was increased by 9.21%,14.77%,13.09%,the average yield of crop straw increased by 9.83%,16.01%,13.02%,and the aboveground nitrogen uptake increased by 10.46%,14.83%,13.54%respectively with the addition of biochar,bentonite and polyacrylamide.3.The nitrogen output from farmland in Hetao irrigation area was respectively crop uptake,nitrogen leaching,ammonia volatilization and nitrous oxide emission,accounting for 67.66⁸3.68%,12.78²5.41%,2.54⁷.42%and 0.58¹.28%.The average leaching loss of biochar,bentonite and polyacrylamide decreased by23.1%,35.45%,27.13%,and the average ammonia volatilization loss decreased by34.81%,52.72%,37.81%respectively compared with the control.The application of biochar did not affect the soil N₂O emission.The average nitrous oxide emission of bentonite and polyacrylamide decreased by 37.31%and 35.84%compared with the control.Based on the comprehensive consideration of environmental benefits and crop yields,bentonite and polyacrylamide are more suitable for application in Hetao Irrigation District.