不同土地利用和施肥方式对土壤酶活性及相关肥力因子的影响

以中国科学院海伦农业生态实验站长期定位试验为平台，研究了不同土地利用和施肥方式对土壤酶活性和相关肥力因子的影响，结果表明，种植苜蓿和土地休闲两种方式与裸地相比脲酶、转化酶、磷酸酶、过氧化氢酶活性、土壤全碳、全氮含量和碱解氮、速效磷、速效钾含量均显著增加。其中，脲酶活性增加了24.5%和25.0%，转化酶活性增加了18.4%和18.9%，磷酸酶活性增加了54.6%和50.4%，过氧化氢酶活性增加了8.52%和59.3%，土壤全碳、全氮含量分别增加了13.8%、13.0%和36.8%、33.7%，但苜蓿和休闲两种方式间无显著差异。不同施肥方式相比，土壤酶活性、土壤全碳、全氮含量及土壤养分含量相差显著，其高低顺序为:NPKOM （氮磷钾肥＋有机肥）＞NPKST （氮磷钾肥＋秸秆）＞NPK（氮磷钾肥）＞CK （无肥）；施肥，特别是有机肥，显著提高了土壤酶活性，使土壤全碳、全氮、有效养分含量显著增加。表明黑土经自然恢复和人工恢复及施肥后土壤肥力提高，土壤质量得到改善。

Effects of land uses and fertilization systems on soil enzyme activities and nutrients

Soil enzymes play an essential role in catalyzing reactions necessary for the decomposition of organic matter and nutrient cycling in ecosystems, involving a range of plants, microorganisms, animals and their debris. In this paper, black soil samples at the depth of 0-20 cm were collected from the Hailun Agricultural Ecology Station of Chinese Academy of Sciences to study the effects of different land uses and fertilization systems on urease, invertase, phosphatase, and catalase activities, total carbon (TC), nitrogen (TN), alkaline hydrolytic nitrogen, available P and available K. The results showed that soil enzymes activity, TC, TN alkaline hydrolytic nitrogen, available P and available K in both clover land and fallow land significantly increased compared with bald land, in which urease activity increased by 24.5% and 25.0%, invertase activity 18.4% and 18.9%, phosphatase activity 54.6% and 50.4% and catalase activity 8.52% and 59.3%, TC and TN increased by 13.8%, 13.0% and 36.8%, 33.7%, respectively. However, there was no significant difference between clover land and fallow land. There was a significant difference of soil enzymes activities, TC, TN and available nutrients contents among the treatments under different fertilization systems, which followed same order: nitrogen, phosphorus and potassium fertilizers plus organic manure (NPKOM) > nitrogen, phosphorus and potassium fertilizers plus straw (NPKST) > nitrogen, phosphorus and potassium fertilizers combination (NPK) > control (CK). Fertilization, especially organic manure application, could significantly increased soil enzymes activities, TC, TN and available nutrients contents. These results suggested that black soil fertility and quality could be improved either by natural or artificial reclamation or by fertilization.