Effects of different fertilization and irrigation measures on nitrogen distribution and leaching in unsaturated zone

YANG Zhixiang; LIU Xiaohan; ZHENG Xilai; FANG Yunhai

doi:10.13984/j.cnki.cn37-1141.2025.04.019

Abstract：Nitrogen pollution of groundwater is a global environmental problem,and fertilization and ir-rigation measures are the key factors affecting nitrogen leaching.On the basis of field investigation and laboratory test,this paper quantitatively studied the distribution characteristics and leaching failure ef-ficiency of dissolved organic nitrogen,ammonium and nitrate in the unsaturated zone by different ferti-lization and irrigation measures.The results showed:(1)The concentrations of dissolved organic ni-trogen,ammonium and nitrate in the soil surface increased with the proportion of organic fertilizer,but in the root zone and vadose zone,the concentration of nitrate nitrogen increased with the proportion of organic fertilizer;however,the concentration distribution of dissolved organic nitrogen and ammonium was not affected by any fertilization measures;(2)Under the same irrigation amount,irrigation fre-quency was the main factor affecting the amount of nitrogen leaching into the ground,the lower the ir-rigation frequency,the higher the amount of nitrogen leaching;however,the ratio of organic fertilizer-inorganic fertilizer and the number of top dressings could only affect the amount of nitrogen leaching in the surface and root zone,and the amount of nitrogen stored in the vadose zone;(3)Only the ratio of organic fertilizer-inorganic fertilizer could affect the contribution rate of dissolved organic nitrogen and ammonium to nitrate leaching.When the proportion of organic fertilizer was 25％,50％and 75％,the contribution rate was 32％,50％,71％and 31％,23％,13％.This study provides reliable technical support for the prevention and assessment of groundwater pollution.