Nitrate Vertical Transport and Simulating Model in Saturated Soils in Typical Region
典型地区饱和土壤中硝态氮垂直运移及拟合

By simulating soil column in laboratory, the nitrate vertical transport characteristics in farmland soil in Fengqu region of Henan Province were studied. The results show that, under saturated soil condition, the different concentrations of nitrate (100 mg x L(-1) 200mg x L(-1)) had no obvious influence on the breakthrough curves (BTCs) of nitrate vertical transport. When the soil columns were eluted by nitrate solution containing co-existing cations (K+ and Ca2+), the BTCs of nitrate vertical transport in the topsoil(0 - 30cm) of yellow fluvo-aquic soil and aeolian sandy soil were very similar. However, the outflow time of nitrate in the middle and bottom soil layers in the yellow fluvo-aquic soil was significantly extended, when the soil columns were eluted by nitrate solution containing Ca2+. The longer the outflow time of nitrate transport out of soil column was, the evener and lower the peak of the BTCs was. The mathematical model, CXTFIT2.0, could be applied to accurately estimate nitrate leaching mass in the saturated soil with steady-state flow condition. The fitted BTCs were in good agreement with the observed BTCs, which had high correlative coefficients (0.8594 - 0.9978).