亚热带稻田土壤微生物生物量碳、氮、磷状况及其对施肥的反应特点

Microbial Biomass C,N and P and Their Responses to Application of Inorganic and Organic Fertilizers in Subtropical Paddy Soils

以湖南省6个稻田长期定位监测点为对象,研究了亚热带地区稻田土壤微生物生物量碳氮磷(C、N、P)状况及其对施肥(包括化肥、秸秆还田和有机肥)的反应状况。结果表明,在相同施肥条件下,稻田土壤微生物生物量C、N、P含量(分别为310—1270、33.0—193、5.9—28mg/kg土)明显高于报道的旱作土壤的含量,说明稻田有较好的土壤微生物生物量维持能力。各监测点土壤微生物生物量C、N、P含量及其对施肥的反应存在很大的差异。施化肥(NPK)对半数监测点的土壤微生物生物量C、N、P含量影响不大,秸秆还田或施用有机肥则均有明显提高,但各监测点的提高幅度差别很大。尽管如此,增加新鲜有机物的投入(如秸秆还田和施有机肥)是提高稻田土壤微生物生物量及其对养分的固持能力的主要途径。土壤微生物生物量C、N、P平均占土壤有机C、全N和全P的2.9%、3.6%和2.1%,且受施肥的影响较小。

The amounts of the microbial biomass C?N?P and their responses to the application of inorganic and organic fertilizers in subtropical paddy soils were studied, using 6 longterm field experiments.Results demonstrated that under the same fertilizer practices, the amounts of microbial biomass C?N?P(310-1270? 33.0-193? 5.9-28 mg/kg soil,respectively)in paddy soils were generally larger than those in upland arable soils, as indicated in previous publication.This suggests that paddy soil has relatively strong ability to maintain the microbial biomass.However,the amounts of the microbial biomass C,N,and P and their responses to the application of fertilizers varied largely with the types of soil and fertilizers.In over a half of the experiments investigated, the amounts of the microbial biomass C,N,and P in the soils was not significantly affected by the application of inorganic fertilizers (NPK) but generally increased by straw incorporation and the application of manure, although the extent of increases varied largely between experimental sites.It is thus proposed that increasing the input of organic mater(e.g.straw and manure) is an effective way to enhance the size of the microbial biomass and its capacity to restore nutrients in paddy soils.The amounts of the microbial biomass C,N and P in the soils accounted,in averages,for 2.9%,3.6%, and 2.1% of total organic C, N and P. These percentages were little affected by the application of the fertilizers.