小麦-玉米轮作体系长期施肥对(土娄)土微生物量碳、氮及酶活性的影响

Effects of long-term fertilization on carbon and nitrogen and enzyme activities ofsoil microbial biomass under winter wheat and summer maize rotation system

以20年(土娄)土小麦-玉米轮作体系长期肥料定位试验为平台,探讨不同施肥模式下土壤化学肥力要素、微生物量碳、氮及酶活性的响应。试验包括不施肥(CK)、单施氮肥(N)、氮磷(NP)、磷钾(PK)、氮磷钾(NPK)、NPK+秸秆(SNPK)以及不同量有机肥+NPK(M1NPK、M2NPK)等8种施肥模式。结果表明,与CK相比,长期施用氮、磷肥提高土壤有机碳含量达34.0%、全氮34.0%、全磷58.5%、速效磷608.9%、微生物量碳23.3%、微生物量氮54.0%、蔗糖酶活性53.9%、脲酶132.6%、碱性磷酸酶29.9%以及脱氢酶40.9%。NPK处理与NP处理效果相似,钾素效果甚微。作物秸秆还田配合氮、磷、钾化肥与施氮、磷、钾肥相比没有明显影响土壤有机碳、氮和磷水平,但是显著提高微生物量碳的含量(29.5%)、碱性磷酸酶(23.0%)和脱氢酶(26.9%)的活性。有机肥配合氮、磷、钾与其他施肥处理相比,显著提升土壤化学肥力要素,微生物量碳、氮和酶活性,特别是引起了磷素的大量富集(速效磷含量大于150 mg/kg)。因此,(土娄)土不施有机物情况下,氮磷配合可以提高土壤化学和生物肥力,作物秸秆还田配合氮磷钾化肥的培肥效果优于氮磷钾化肥配合,而合理的有机无机肥配合是(土娄)土提升化学肥力和保证土壤生物健康的最佳施肥模式。

Fertilizer management has significant effects on both soil chemical and biological properties. This study was designed to examine the effects of continuous fertilization, straw incorporation, and manuring on the soil chemical fertility, microbial biomass and activities of enzymes involved in mineralization of C, N, and P on a long term （20 years） field trial with winter wheat and summer maize rotation system under temperate conditions in Shaanxi of China. Treatments at the site included applications of the recommended doses of nitrogen （N） , nitrogen and phosphorus （NP）, phosphorus and potassium （PK）, nitrogen, phosphorus and potassium （NPK）, wheat/maize straw （S） with NPK （SNPK） , dairy manure （M） with NPK （ M1NPK and M2NPK） and un-amended control （CK）. Compared with the CK, the contents of soil organic carbon, total nitrogen, total phosphorus, available phosphorus, microbial biomass carbon and microbial biomass nitrogen are increased by 34. 0% , 34.0% , 58.5% , 608.9% , 23.3%, and 54.0% under the long-term application of the NP, respectively, and the activities of invertase, urease, alkaline phosphatase and dehydrogenase are increased by 53.9% , 132.6% , 29.9% and 40. 9%. Nevertheless, the NPK has similar effects on above parameters as the NP. In comparison with the NPK, the SNPK has no significant effects on levels of soil organic carbon, nitrogen and phosphorus, but considerably increases microbial biomass C （29.5 % ）, alkalinephosphatase （23.0%） and dehydrogenase （26.9%） activities. The soils with longterm applications of MNPK have the maximum levels of soil organic carbon, nitrogen and phosphorus, and highest microbial biomass and enzyme activities, while, large concentration of phosphorus in MNPK soils is accumulated. It concludes that the application of the NP could enhance soil fertility in the circumstance of inorganic fertilization, the SNPK is superior to the NPK in improving soil biological health, and the MNPK is the best fertilizer management in enhancing both soil chemical and biological fertility on Lou soil.