Nitrate Accumulation And Nitrogen Balance Of Drip And Sprinkler Irrigated Potato In Northern Yin Mountains Of Inner Mongolia

The Northern of Yin Mountain is located in Chinese farming and pastoral ecotone.In recent years,with the development and utilization of groundwater,some of the traditional dry farming agriculture gradually shifted to water-saving irrigation agriculture.However,applying excessive nitrogen fertilizer in farmland may cause environmental risk.In order to clarify the accumulation of nitrate and nitrogen balance in the water-saving irrigation of potato fields in the northern of Yinshan Mountain,this paper combines the methods of household research and field sampling to study the nitrogen balance of cooperatives,large farmers and small farmers in Wuchuan County and Siziwangqi potato planting areas in the northern of Yinshan Mountain,and to detect the nitrate content in soil and groundwater.It aims to provide reference and guidance for the application of reasonable nitrogen fertilizer in potato planting in the northern part of Yinshan Mountain,Inner Mongolia,to avoid or reduce nitrate pollution.The main results are as follows:1.In the northern part of Yinshan Mountain,the nitrogen input of irrigated potato field is mainly chemical fertilizer,accounting for 42.7%-54.4%of the total nitrogen input,with an average of 48.7%.The amount of nitrogen input varies depending on the planting area,the type of growers and the year of planting,and the crop yield is taken as the main output pathway,accounting for more than 72%of total nitrogen output(72.9%～80.1%);Leaching loss accounted for 17.7%-24.9%of total nitrogen output;ammonia volatilization and denitrification of nitrogen loss is the smallest,accounting for the total output of nitrogen 2.1%to 2.4%.2.The nitrogen in the irrigated potato field in the northern part of Yinshan Mountain is in surplus state,about 277.1-494.4 kg/ha,with an average of 289.0 kg/ha.The nitrogen surplus and variation of the cooperatives are the highest,and the variation range is 18.6-742.9 kg/ha,with an average value of 343.7 kg/ha.3.The content of Nitrate-N in the potato field of the northern part of Yinshan Mountain is different with the variation in farmlands and the soil depth.The Nitate-N mainly concentrated in the 30-90 cm soil layer,about 4.4-192.9 kg/ha,with an average of 80.4 kg/ha.The variation of Nitrate-N content in 60-90 cm soil layer is larger than that of the control group,and the average value decreased from 95.1 kg/ha to 54.2 kg/ha in 2015,and decreased by 43.0%.4.The variation of nitrate content in groundwater of irrigated potato field in the northern part of Yinshan Mountain is 5-250 mg/L,with an average of 34.5 mg/L,of which 95.7%up to the national drinking water standard(≤80 mg/L),82.9%up to EU standards(≤50 mg/L);Excess standard rates of China and EU are 4.3%and 17.1%,respectively.In summary,reducing the loss of chemical nitrogen fertilizer and nitrogen leaching loss,especially the cooperatives and large farmers of nitrogen inputs can effectively reduce nitrogen surplus.The Nitrate-N was mainly concentrated in 30-90 cm,which had a trend of infiltration.