长期施肥对不同有机质含量农田黑土活性有机氮组分的影响

为了阐明长期施肥后不同有机质含量农田黑土活性有机氮组分的变化,探讨农田黑土肥力演变对施肥的响应机制,本研究利用黑土生产力长期定位试验,以5个不同有机质(SOM)含量11%(北安)、6%(嫩江)、5%(海伦)、3%(德惠)、1.7%(梨树)农田黑土为研究对象,对比研究了连续施用8年化肥后对土壤全氮及土壤活性氮库不同组分颗粒有机氮(POM-N)、微生物量氮(SMBN)、可溶性有机氮(DON)及轻组有机氮(LFOM-N)的影响。结果表明:与无肥处理相比,长期施用化肥可提高土壤全氮、POM-N、SMBN、LFOM-N的含量(P0.05),对DON的影响不显著。土壤全氮、POM-N、LFOM-N、SMBN含量随土壤有机质含量的降低而降低。在土壤活性有机氮的组分中,颗粒有机氮的贡献率最大。长期施肥对不同有机质含量的农田黑土活性有机氮之间的相关性无影响。

Effects of Long-term Fertilization on Soil Labile Organic Nitrogen in Arable Moliisols Under Different Organic Matter Levels

The paper aims to illustrate the changes of labile organic nitrogen in arable mollisols under different organic matter levels after long-term fertilization and discuss the evolvement mechanism of farmland mollisols fertility responding to fertilization. Using the long- term experiment on mollisols productivity, the authors investigated the effects of 8-year continuous application of chemical fertilizers on labile organic nitrogen in arable mollisols under different organic matter levels. Farmland mollisols with five different soil organic matter (SOM) levels, 11% (Beian), 6% (Nenjiang), 5% (Hailun), 3% (Dehui) and 1.7% (Lishu), were taken as the study objects. Compared with none-fertilization treatment, the long-term application of chemical fertilizers increased the contents of soil organic nitrogen, including microbial biomass nitrogen, particulate organic nitrogen, and light fraction organic nitrogen (except dissolved organic nitrogen). Soil organic nitrogen, microbial biomass nitrogen, particulate organic nitrogen, and light fraction organic nitrogen all decreased with the decline of SOM. Particulate organic nitrogen contributed the most to labile organic nitrogen in all mollisols. Fertilization had no effect for the correlation between organic nitrogen and active organic nitrogen in the studied mollisols.