土壤中硝态氮迁移转化的数值模拟研究

为了揭示不同灌溉强度下土壤中硝态氮浓度的变化规律,选取常德市典型浅层土壤为研究对象,以动态土柱淋滤试验和静态反硝化试验为基础,运用HYDRUS-1D软件建立数值模型对不同灌溉强度下硝态氮浓度的变化进行模拟分析。结果表明:当灌溉强度大于4 cm/d时,灌溉强度超过土壤下渗能力,灌溉水按下渗能力下渗,多余的水会形成地面积水,进而形成地表径流,模拟10 d各组土壤中硝态氮的浓度差异不大;当灌溉强度小于等于4 cm/d时,灌溉水全部下渗到土壤中,模拟10 d后土壤中硝态氮的浓度随灌溉强度的增加而增大。

Numerical simulation study on nitrate-nitrogen transportation and transformation in soil

To reveal the mechanisms of nitrate-nitrogen transformation in soil, the typical shallow soil in Changde area, Hunan Province was selected as research subject. Based on indoor static denitrification test and dynamic soil column leaching test, a mathematical model was established by using HYDRUS-1D software and the concentration variation of nitrate-nitrogen under different irrigation intensity was simulated and analyzed. The results showed that when the irrigation intensity is larger than 4 cm/d that exceeds the soil infiltration capacity, the irrigated water infiltrates according to infiltration capacity and the surplus water yields surface runoff. The nitrate-nitrogen concentrations of various soil samples are tend to be even after 10 days simulation; when the irrigation intensity is less than or equal to 4 cm/d, all irrigation water infiltrates into soil and the nitrate-nitrogen concentrations increases with the increase of irrigation intensity after 10 days.