Effects Of Micro-water Spraying Fertilizer Integration On Soil Nitrogen Balance And Environment

There exist common problem such as the low utilization of water and nitrogen due to unreasonable irrigation method and nitrogen dosage in southern Shanxi province.The unreasonable pattern of water and nitrogen can not only hinder nitrogen hinder from playing its effect to increase crop production,also cause a series of environmental pollution problems such as water pollution,air pollution,which has become the main restriction to regional agriculture sustainable development in southern Shanxi province.In view of the above problems,a field experiment was carried out in Hancun Farm experimental base of Shanxi academy of agricultural sciences in 2017-2018.There are five treatments:CK,WN₀,WN₁,WN₂ and WN₃.The study studied the effects of water and fertilizer integration to soil water transport and distribution,enzyme activity,winter wheat yield,quality,nitrogen fertilizer utilization and gas emission to explore the best pattern of irrigation and nitrogen application and to provide technical support and theoretical basis in the increase of winter wheat yield and the reduction of environmental pressure.The main results of the experiment are as follows:?1?Soil moisture content under different water and nitrogen treatments changed significantly during the whole growth period of winter wheat.After a large amount of irrigation in the overwintering period and jointing period,the soil water content of 0-40cm under the treatment of flood irrigation within a short period was higher than that under micro-sprinkling irrigation.However,the water content in CK treatment decreased greatly over time and was finally lower than that under micro-sprinkling irrigation.In the later growth period of winter wheat,the overall water content of CK was lower than that under micro-sprinkling irrigation.Compared with traditional flood irrigation,integrated micro-water spraying fertilizer can save water of 2550m³/hm²,which is conducive to maintain soil water content during the whole growth period of winter wheat and ultimately promote crop growth and development.?2?The integration of micro-water spraying fertilizer increase the soil enzyme activity in the main growth period of winter wheat.The activity of leucine aminopeptidase?LAP?,acetylaminoglycosidase?NAG?and?-xylosidase?BXYL?was increased by plenty of irrigation in winter wheat.The activity of LAP,NAG,BXYL and-fibrous diglucosidase?CBH?was increased by plenty of irrigation in jointing period.The activities of CBH,LAP,NAG and BXYL in soil were improved after nitrogen fertilizer reduction.?3?Integration of micro-water spraying fertilizer is benefit to improve winter wheat yield and nitrogen utilization efficiency?PEPN?and maintain winter wheat quality.Compared with CK treatment,WN₂ treatment reduces irrigation by 63%,nitrogen application amount by 25%and yield by 16.25%.The reduction and backward shift of nitrogen fertilizer could improve the comprehensive quality index of winter wheat.The PEPN of WN₁ is 3.8 percent higher than CK's.WN₂ is 14.7%higher than PEPN of WN₃.?4?The integration of micro-water spraying fertilizer was conducive to reduce the cumulative emission of N₂O-N in different periods and the total cumulative emission of N₂O-N.The cumulative emissions in the growth period of N₂O-N treated by CK and WN₀were generally presented as the first fertilizer application>the second fertilizer application>the cumulative emissions in the growth period treated by WN₁,WN₂ and WN₃ were generally presented as the first fertilizer application>the second fertilizer application.The cumulative emission of N₂O-N of CK was 8.23%higher than WN₁,and WN₂ was 13.70%lower than WN₃.?5?The integration of micro-water spraying fertilizer was conducive to reduce the cumulative emission of N₂O-N in different periods and reduce the total cumulative emission of N₂O-N.The cumulative emissions of N₂O-N in each treatment generally showed basal period>first fertilizer application and>second fertilizer application.The cumulative total emission of N₂O-N of CK was 23.59%higher than WN₁ and 3.25%lower than WN₃.?6?The integration of micro-water spraying fertilizer can significantly reduce the nitrogen balance value.Compared with CK,WN₂ significantly reduced the nitrogen balance value of 111 kg·hm^-2,reduced the risk of nitrogen soil residue,leaching loss and gas loss,which had great environmental benefits.?7?Under the premise of maintaining the yield,the integration of micro-water spraying fertilizer can reduce the gas loss of soil nitrogen and reduce the air pollution.Compared with the conventional flood irrigation treatment?CK?,reducing nitrogen fertilizer measure?WN₂?can reduce nitrogen fertilizer by 25%,and reduce the cumulative nitrogen emission by 30%.To sum up,the winter wheat in southern Shanxi province was sprayed three times and in the way of the reduced amount of nitrogen application was the optimal treatment,that is,the overwintering water 450m³·hm^-2+water 600m³·hm^-22 in joint period+grouting water450m³·hm^-2,the nitrogen application was 225kg·hm^-2,the basal fertilizer was 135kg·hm^-2before sowing,and the top dressing was 90kg·hm^-2during jointing.This treatment is beneficial to maintain the soil moisture content of 0-40cm,improve the soil enzyme activity in the main growth period of winter wheat,and then promote the increase of the yield components of winter wheat,and finally increase the yield.In addition,the optimized nitrogen application also reduced the nitrogen balance value,reduced the ammonia volatilization and the nitrous oxide cumulative emissions,and reduced the air pollution.