Effects of nitrogen fertilization on leaching characteristics of NO₃^--N and base cations in latosol

Reasonable selection of different nitrogen fertilizers has an important influence on the increases of crop yield and rural incomes and the improvement of soil acidification. Taking the latosol in Haikou, Hainan province as research object, a soil column leaching experiment was conducted to study the leaching characteristics of NO-3-N and Ca2+, Mg2+, K+ and Na+. The results show that the cumulative leaching amounts ofNO-3-N are in order, ammonium sulfate ammonium nitrate urea N0, and have a positive correlation with fertilizer rate in a linear equation, y=3.3064x+315.74 (R2=0.8848). The cumulative leaching amounts of base cations of all treatments are in order Ca2+Mg2+K+Na+, and the total cumulative leaching amounts of base cations ( kg/ha) are in the tendency of ammonium sulfate (1821.12)ammonium nitrate (1080.27)urea (872.24)N0 (417.23). The migration rates of base cations of latosol are in order: ammonium sulfate (26.28%) ammonium nitrate (13.37%) urea (11.78%), and the best fitting equations for the base cations migration rates of latosol in the urea, ammonium nitrate and ammonium sulfate treatments are linear equation, y=0.1178x+123.18 (R2=0.9121), power equation, y=15.634x0.4423 (R2=0.9259), and logarithmic equation, y=128.38e0.0007x (R2= 0.9244), respectively.