化肥减量对麦田土壤微生物量及微生物区系的影响

为了解化肥减量和有机培肥配施对冬小麦田土壤微生物的影响,以单施常量化肥(表示为NPK,分别施尿素、磷酸二铵和硫酸钾251.8、255.7和375.2kg.km-2)为对照,设置不同化肥(不减量、减量30%、减量50%和减量70%)和有机肥(18 000、25 500和34 500kg.km-2,分别用LM、MM和HM表示)配施处理,采用系列稀释平板法和氯仿熏蒸培养法分别测定了不同处理下土壤微生物量碳、氮以及微生物区系分布的差异。结果表明,有机无机肥配施显著增加了麦田土壤微生物量碳、氮以及细菌、固氮菌、放线菌等微生物数量,但不影响土壤真菌数量。施肥效果在化肥不减量时随有机肥施用量增加呈上升趋势,在化肥减量时以50%NPK+MM处理最佳。说明化肥适度减量和配施有机肥能够改善土壤微生物量,有利于提高土壤肥力。

Effects of Chemical Fertilizer Reduction on Soil Microbiological and Microbial Biomass in Wheat Field

In order to explore the effects of chemical fertilizer reduction with organic fertilizer application on soil microbes,winter wheat was planted under diffierent fertilizer treatments.4 chemical fertilizer(NPK) levels of 100%,70%,50% and 30%,and three organic fertilizer(M) level of 18 000,25 500 and 34 500 kg·km-2(representing with LM,MM and HM,respectively) were selected in the experiment with single NPK application as CK.In the treatments with 100% NPK,the explicating amount of urea,diammonium phosphate and potassium sulfate per hectare were 251.8,255.7 and 375.2 kg·km-2,respectively).The serial dilution plate culture method and chloroform evaporated method were used to determine the difference of soil microbial carbon,nitrogen contents and the distribution of microbial flora with different treatment.The results indicated that the together application of organic and inorganic fertilizers significantly increased the content of soil microbial carbon and nitrogen,the number of microbes such as bacteria,nitrogen-fixing bacteria,actinomyces,but did not affect the number of soil fungus.The effect of fertilizers rose with the increasing of organic fertilizer under no reducing of chemical fertilizer.the best treatment was 50%NPK + MM when reducing chemical fertilizer.It illustrated that moderate fertilizer reduction with matching application of organic fertilizer could improve soil microbial biomass in favor of soil fertility.