建三江地区不同土地利用类型的反硝化潜力

Denitrification Potential of Different Land-use Types in Jiansanjiang District

建三江地区农业用地的扩张和大量氮素化肥的使用,导致农田外环境中硝酸盐含量的增加,而减少硝酸盐含量的一种重要方式是在农田与接收水体间合适的地方恢复自然湿地,以通过反硝化作用去除径流中的硝酸盐含量。本文应用硝态氮剩余量法,测定建三江地区不同土地利用类型的反硝化潜力。结果表明,湿草甸反硝化潜力最高,其次是水田、旱地、林地及各级渠道,荒草地的反硝化潜力最小。在有机质、总氮、硝酸盐这几个影响因子中,有机质含量对与土壤的反硝化潜力影响较大,在P<0.05下的相关系数为0.80,土壤中添加硝酸盐对土壤的反硝化潜力有一定的促进作用,总N的含量对其有一定影响。从结果中可以看出建三江地区湿草甸是恢复自然湿地较合适的位置。

Expansion of agricuhural land and excessive nitrogen fertilizer use in Jiansanjiang has resulted in increasing of the nitrate load of the river. One way to reduce this nitrate load is to restore natural wetlands at suitable locations between croplands and receiving water body to remove run-off nitrate through denitrification. Denitrification potential（DP） of different land-use types in Jiansanjiang District was determined using the nitrate surplus quantity method. The results showed that DP of wet meadow was the highest of those land-use types; Paddy field, dry farmland, woodland and ditch followed; waster grassland was the lowest. Soil organic matter significantly affected DP. Its correlation coefficient with DP was 0.8 at P〈0.05. Nitrate addition in soils increased the DP. It was evident from these results that wet meadow in Jiansanjiang district was more suitable locations to restore natural wetland for mediating nitrate loss from agricultural runoff.