裂缝对稻田土壤溶液中氮运移的影响

采用温室中土柱培养试验方法，研究了裂缝对稻田土壤溶液中N元素动态运移规律。结果表明，青紫泥和黄斑田从开裂到稳定，土壤溶液中的硝态氮浓度随着时间的延长而降低，亚硝态氮浓度随时间而波动，而这2种氮的浓度在没有开裂的小粉土中却随着时间而呈乘幂增加。在自然干燥过程中产牛的裂缝性质对土壤溶液中的硝态氮和、亚硝态氮浓度变化有显著影响，但是对铵态氮浓度的变化没有影响。裂缝从产生到稳定的过程中，深层土壤巾的硝态氮浓度一直在减少，这样有利于减少硝态氮的下渗，减少硝态氮对地下水的污染。

Effect of Cracks on Nitrogen Transport in Paddy Soil Solutions

Three kinds of paddy soils were added enough water, then dried under natural condition in a greenhouse in the soil columns incubation experiments. The experiments showed Qingzini and Huangbantian with high clay contents produced cracks, but the cracks didn't appear in Xiaofentu with low clay contents. The concentrations of total nitrogen and nitrate decreased with the incubation time, and the nitrite concentration fluctuated in cracked Qingzini and Huangbantian 0.9m depth soil solution; while, in no cracked Xiaofentu 0.9m depth soil solution, their concentrations increased by power curves. The important properties of soil cracks, namely volume of cracks, internal crack surface and soil- crack depth had significant effects on the change of nitrate and nitrite concentrations but not ammonium in the soil solutions. From cracks producing to stabilizing, the concentration of nitrate in the deep depth soil decreased continually, which was helpful to decrease the leakage of nitrate and pollution of groundwater.