Modeling urea, ammonium, and nitrate transport and transformations in flooded soil columns
Modeling urea, ammonium, and nitrate transport and transformations in flooded soil columns
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模拟尿素、铵和硝酸盐在淹没土柱中的传输和转化
DOI：
10.1097/00010694-199902000-00007
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
H. Selim
中科院分区：
文献类型：
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作者：
Liwang Ma;C. Lindau;C. Hongprayoon;W. Burhan;B. Jang;W. H. Patrick;H. Selim
了解有机氮（尿素，铵和硝酸盐）引入湿地的命运是重要的湿地恢复和环境质量。然而，氮在湿地中的转化是复杂的氧化和还原土壤条件的共存。在这项研究中，我们研究了15 N-尿素，其降解产物（15 NH 4和15 NO3）在实验室柱填充克劳利粉壤土，在路易斯安那州西南部的主要水稻土的运输和转化。在实验过程中保持2厘米的洪水层，以模拟湿地条件。用添加了脲酶抑制剂[N-（正丁基）硫代磷酰三胺]的灭菌土柱测定了尿素在土壤中的扩散。尿素转化进行了研究，使用15 N-尿素，并在0.5，1，2，4，和6天后，尿素应用的降解产物（铵和硝酸盐）进行了测量。在无菌条件下，采用间歇实验法测定了尿素和NH 4的吸附等温线.建立了描述尿素、NH 4和NO3在土壤中扩散转化的扩散方程组。假定尿素水解仅发生在土壤剖面中，硝化作用发生在洪水和表层土壤中。反硝化作用可能会发生在洪水和土壤剖面取决于氧气消耗。尿素和铵态氮在土壤剖面中的分布预测值与试验值相关性均很好（r 2 > 0.91）。虽然在每个采样时间的硝酸盐浓度被低估，该模型高估了8.7%的硝酸盐的量在6天的实验期间。
Understanding the fate of organic nitrogen (urea, ammonium, and nitrate) introduced into wetlands is important for wetland restoration and environmental quality. However, the transformation of nitrogen in wetlands is complicated by the coexistence of oxidized and reduced soil conditions. In this study, we investigated the transport and transformations of 15 N-urea, and its degradation products ( 15 NH 4 and 15 NO 3 ) in laboratory columns packed with Crowley silt loam, a major rice soil in southwest Louisiana. A 2-centimeter floodwater layer was maintained during the experiments to simulate wetland conditions. Sterilized soil columns with the addition of urease inhibitor [N-(n-butyl) thiophosphoric triamide] were used to measure urea diffusion in the soil. Urea transformations were studied using 15 N-urea, and the degradation products (ammonium and nitrate) were measured at 0.5, 1, 2, 4, and 6 days after urea application. Adsorption isotherms for urea and NH 4 were determined using batch experiments under sterile conditions. A system of diffusion equations (DEs) was formulated to describe urea, NH 4 , and NO 3 diffusion and transformation in soil. Urea hydrolysis was assumed to take place in the soil profile only, and nitrification in the floodwater and the surface soil layer. Denitrification may take place in both the floodwater and soil profile depending on oxygen depletion. Predicted urea and ammonium distributions in the soil profile following urea application were highly correlated to their experimental values (r 2 > 0.91). Although nitrate concentrations at each sampling time were underpredicted, the model overpredicted by 8.7% the amount of nitrate denitrified during the 6-day experimental period.