Effects of Long-term Different Fertilizations on Composition and Stability of Soil Aggregates in a Greenhouse Soil

The effects of different fertilizations on the content,distribution,and stability of soil aggregates were studied by a long-term fertilization experiment in a greenhouse soil.Results showed that the greatest size of wet stable aggregates of the greenhouse soil with organic fertilizer was in the 0.125~0.25 mm fraction,while the greatest size of wet stable aggregates of the greenhouse soil without organic manure was in the 0.053~0.125 mm fraction.The content of wet stable aggregates in 0.25 mm fraction was significantly lower than that in the 0.25 mm fraction.In the 0.125 mm fraction,the contents of wet stable aggregates with organic fertilization(AN0) and the combined organic and inorganic fertilization(ANPK) were higher than those with(BNPK) and without(BN0) inorganic fertilizer.The long-term application of organic fertilizer could enhance the formation of wet stable aggregates from macro-aggregates to micro-aggregates.The stability index of soil aggregates in different treatments was in the order of ANPK BNPK AN0 BN0.Fractal dimension(D),geometric mean diameter(GMD),and mean weight diameter(MWD) were all suitable to evaluating wet stable aggregates of the greenhouse soil.