交替冻融对东北地区典型土壤氮磷浓度的影响

研究了交替冻融对东北地区黑土、暗棕壤和水稻土中的全氮、有效氮、全磷和有效磷的影响。结果表明，经过15次交替冻融后，三种类型土壤的全氮浓度均未发生明显变化，说明在交替冻融过程中，硝化与反硝化共同作用并不明显。由于冻融作用增强土壤释水性和水分渗透性，经15次交替冻融后，黑土、暗棕壤和水稻土的有效氮浓度均有所升高，以水稻土最显著，上升了31.25%。三种土壤全磷浓度均在初次冻融后大幅增高，总体呈升高趋势，分析原因主要是冻融作用破坏了土壤团聚体，增加了与消化液反应的机会。经15次交替冻融后，黑土和水稻土的有效磷浓度分别上升17.72%和56.16%，暗棕壤的有效磷浓度下降35.19%，这说明交替冻融过程中土壤有效磷的变化不但取决于土壤的C/P，还受土地利用类型的影响，林地的有效磷浓度可能由于发生磷的净固定而降低。

Freeze-thaw Cycle Effects on Nitrogen and Phosphorus Content in Typical Soils of Northeast China

The influence of freeze-thaw cycles (FTC) on the total nitrogen, available nitrogen, total phosphorus and available phosphorus of black soil (BS), dark brown soil (DS) and paddy field soil (PS) were studied. The result demonstrated that the total nitrogen degree of the three types of soil had no significant changes after 15 times of FTC, which suggested that nitrification and denitrification had no obvious co-effect during this process. After 15 times of FTC, the available nitrogen degree of the three types of soil increased as a result of intensifying of soil water releasing and water permeability caused by FTC, and was the most remarkable for the available nitrogen of the PS which was increased by 31.25%. The total phosphorus degree of the three types of soil increased significantly after the first FTC, and then showed the increased tendency gradually, which was probably due to the damage of soil aggregate by FTC and the increased opportunities of reacting with the digestive system. After 15 times of FTC, the available phosphorus degree rose by 17.72% and 56.16% in BS samples and PS samples, respectively, and descended by 35.19% in DS samples. This showed that the change of available phosphorus degree was not only influenced by the C/P degree of soil but also by the land use pattern, and the available phosphorus degree could descend due to the net immobilization of phosphorus in forest land.