Preliminary Study on Nitrogen Loss and Dynamic Change of Farmland under Different Water and Nitrogen Measures

【Objective】 In view of the serious problem of nitrogen loss caused by improper management of corn water and fertilizer, the effects of different water and nitrogen measures on nitrogen leaching loss in farmland was studied with corn in Yellow Irrigation Area of Ningxia as the test material. 【Method】 Using the methods of field experiment, sampling, indoor analysis and biostatistics, five treatments were set up CON (conventional treatment), RN(nitrogen reduction), SRN(nitrogen reduction and water saving), SMN(water saving and increasing organic fertilizer application) and CRF(controlled-release fertilizer application). 【Result】 Soil water content was one of the factors affecting leaching capacity, while irrigation volume was the main factor affecting leaching capacity. Water-saving and controlled irrigation treatment (SRN and SMN) produced less leaching water than conventional irrigation treatment (CON, RN and CRF), and compared with conventional irrigation, the water amount of water leaching in water-saving controlled irrigation treatment decreased by 14.6%-18.4%; Total nitrogen, soluble total nitrogen and nitrate nitrogen concentrations in soil leached water showed a decreasing trend during the year, all of which showed peaks after base fertilization or the first topdressing of nitrogen fertilizer. It was the key period to control nitrogen loss, and it also showed that nitrogen application was the main factor affecting the nitrogen concentration in leaching water. From 2016 to 2018, the order of total nitrogen spray loss was CON> RN > SRN > SMM > CRF, and the total nitrogen spray loss of CRF decreased by 21.4-43.0 kg/hm² compared with CON. 【Conclusion】 CRF treatment in this test has the best effect on reducing nitrogen leaching loss. Compared with CON treatment, the reduction ratio of total nitrogen leaching loss is 68.4%-74.7%.