有机肥和化肥长期施用对土壤活性有机氮组分及酶活性的影响

本文以中国农业科学院山东禹城长期定位施肥试验为平台，研究了长期施用有机肥和化肥26年后对土壤活性氮库不同组分［颗粒有机氮（POM-N）、 可溶性有机氮（DON）、 微生物量氮（SMBN）及轻组有机氮（LFOM-N）］及土壤酶活性的影响。结果表明，与不施肥相比，长期施肥显著提高了土壤全氮、 颗粒有机氮、 可溶性有机氮、 微生物量氮以及轻组有机氮的含量，长期施有机肥效果好于化肥，施用高量有机肥效果好于施用常量有机肥。常量施用量下，50%有机肥和50%化肥配施处理其土壤全氮和活性有机氮库各组分含量与高量化肥处理的相当。长期施化肥处理土壤全氮及活性有机氮库各组分含量随施肥量的增加而显著增高。POM-N对土壤全氮的贡献率最高，且明显受施肥方式的影响，LFOM-N对土壤全氮的贡献率不随施肥方式的改变而变化。长期施肥处理土壤脲酶、 碱性磷酸酶和蔗糖酶活性显著增加，它们之间及与土壤全氮、 速效磷及有机碳含量间呈现显著或极显著相关性，脲酶活性与土壤各活性氮组分间也存在显著或极显著相关性； 但长期施肥后土壤过氧化氢酶的活性低于不施肥

Long-term effects of mineral versus organic fertilizers on soil labile nitrogen fractions and soil enzyme activities in agricultural soil

In this paper,  the effects of long-term application of organic fertilizer and chemical fertilizer on soil labile nitrogen fractions and some kinds of soil enzyme activities (urease,  catalase,  alkaline phosphatase and sucrase) were studied based on a 26-year long-term field experiment in Chinese Academy of Agricultural Sciences Research Station in Yucheng City,  Shandong province,  China. The results show that,  compared with CK,  long- term fertilization significantly increases soil total nitrogen,  particle organic nitrogen (POM-N),  dissolved organic nitrogen (DON),  microbial biomass nitrogen (MBN) and light fraction organic nitrogen(LFON) contents. Treatments of applying organic fertilizers alone could improve soil total nitrogen and labile nitrogen fractions contents more effectively than the treatments of applying mineral fertilizers alone. The highest soil total nitrogen and labile nitrogen fractions contents appear in treatment of double organic fertilizer input,  then is the treatment of common organic fertilizer input. The similar soil total nitrogen and labile nitrogen fraction contents are in treatment of applying 50% organic fertilizer and 50% mineral fertilizer and the treatment of applied double amount of mineral fertilizers. The soil total nitrogen and labile nitrogen fraction contents are improved with the increased input levels of mineral fertilizers. POM-N is the main contributor of the soil total nitrogen,  affected by fertilizer types and input levels. There is no difference in the contribution of LFOM-N to the soil total nitrogen among all the treatments,  suggesting that fertilizer application types and input levels couldn’t affect the contribution of LFOM-N to the soil total nitrogen. The activities of soil urease,  alkaline phosphatase and sucrase are increased significantly by the application of fertilizers. The three enzyme activities are correlated significantly with each other,  and also correlated with soil total nitrogen,  available phosphorus and organic carbon,  and closer correlation exists between the urease activity and soil labile nitrogen fractions contents. But the activity of soil catalase is decreased after long-term application of fertilizers