利用染色分析法确定农田土壤中硝态氮垂直运移的研究

Study on Vertical Transport of Nitrate-N with Soil Coloration Analysis in Farmland

利用农田土壤剖面染色并结合田间硝态氮示踪的方法，研究了太湖地区典型的水稻土一白土剖面中优势流和硝态氮在土壤剖面中的运移规律。结果表明：染色法可以分析土壤剖面中大孔隙的分布状况和优势流的路径；染色面积越大的土层，表明该土层的大孔隙含量就越高。在白土剖面上，表层的大孔隙含量最高，20～30cm和55～100cm土层以下大孔隙含量都很低。在田间条件下，优势流是影响硝态氮迁移的主要因素；白土剖面中优势流直接影响的最大深度为78cm，对地下水的影响很大。本试验中地下水的硝态氮含量比未试验前增加了10多倍，这对环境安全影响极大。

The objective of this paper is to study preferential flow and transport rule of nitrate--N in Bai soil pro- file with the soil coloration analysis and nitrate tracing. The results were as follows： the macropore distribution and preferential flow ways could be analyzed by coloration. The larger colored area indicated higher macropore content in every soil layer. In Bai soil profile, the macropore contents of surface layer were the highest. The macropore contents below the third and the fifth soil layers were low. In farmland, preferential flow was the main ways of nitrate--N transport. The preferential flow could affect to about 78 cm in soil profile. The groundwater was affected obviously by preferential flow and nitrate-N content in groundwater was multiplied more than 10 times in this experiment.