典型地区饱和土壤中硝态氮垂直运移及拟合

采用室内土柱模拟的方法, 研究了封丘地区农田土壤中硝态氮垂直运移规律. 结果表明: 在饱和条件下, 不同浓度硝态氮溶液(100mg·L^-1、200mg·L^-1)处理的土壤, 硝态氮运移的穿透曲线间无明显影响. 用含有不同价态陪伴阳离子(K⁺和Ca²⁺)的硝态氮溶液处理黄潮土0～30cm土层和风沙土, 硝态氮运移的穿透曲线基本重合; 而陪伴Ca²⁺硝态氮溶液处理的黄潮土30～60cm、60～90cm土层中硝态氮出流时间具有滞后效应. 硝态氮溶液全部运移出土体所需时间越长, 穿透曲线越平缓、峰值越低. CXTFIT2.0数学模型估算的稳定水流条件下饱和土壤中硝态氮淋失量具有较高精度, 相关系数均达到极显著水平.

Nitrate Vertical Transport and Simulating Model in Saturated Soils in Typical Region

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).