A Study On The Relationship Of Between Soil Humus And Anti-erosion Ability Of Soil Aggregate

Of the soil humus, the components make direct contributions to the formation of soil fertility and aggregates. The soil aggregates is an important index to appraise soil fertility, whose size and content, being the important physical properties, have become an essential index to judge the soil quality and the anti-erosion ability. In order to find out an index closely related to soil erosion from the qualities of soil humus, the research is carried out aiming at finding out the humus mechanism in the process of soil erosion, meanwhile, providing effective theories for the measures taken to reduce soil erosion.The quantity properties of soil aggregate and humus properties were researched in Wolong Natural Reserve in which the vegetation are Dark Coniferous forest, Coniferous and Broadleaf mixed forest, Fargesia under gap of Dark Coniferous forest and Sclerophyllous Oaks (Quercus Sec. suber). It is found that:(1) The surface layer of soil carries the larger number of humus and with the soil depth forward, the number of humus becomes declining. The first layer has the largest number of humus. With the soil depth forward humic acid content becomes gradually decreased while fulvic acid becomes gradually incremental. HA/FA in the soil section except that Sclerophyllous Oaks is more than 1,while the second and third layer of soil is less than 1.(2) The aggregates were found to be in logarithmic-normal distribution, and the geometric mean diameters are negative correlativity to geometric standard deviation. There are larger diameters aggregate under the Coniferous and Broadleaf mixed forest and Sclerophyllous Oaks than that of other vegetations. The range of fractal dimension about soil aggregate of the four vegetations is 2.40-2.78 with more high fractal dimension along with more aggregate size less than 0.25 mm.; among the 12 samples, the fractal dimension of soil aggregate under Dark Coniferous forest and Fargesia under its gap are larger than others soils which shows that they have the worst structures.(3) The soil aggregates under the four vegetations, whose size are 3~lmm and l~0.5mm, have higher stability; and the aggregate size >10mm and 0.5~0.25mm have lower stability. The aggregate stability index of soil under Coniferous and Broadleaf mixed forest is the highest; the others are soil under Sclerophyllous Oaks, Fargesia under gap of Dark Coniferous forest and Dark Coniferous. These showed the Coniferous and Broadleaf mixed forest and Sclerophyllous Oaks were benefit to soil aggregate stability. The total humic is the important factor of influencing the Aggregate Stability Index.(4) The fact that humic-acid-1 and fulvic-acid-1 vary with the depth of soil layer are to be the linear function in Ln y=a Iji x+b.(5) Among the experimented soils, the number of the humus components in Dark Coniferous soil is the smallest, and that of the humus components in Coniferous and Broadleaf mixed forest soil is the largest and the second largest. The soil aggregates in the Coniferous and Broadleaf mixed forest have a higher stability while those in the Dark Coniferous forest have a lower one.In a word, The researches on the soils of the four vegetations (Dark Coniferous forest, Coniferous and Broadleaf mixed forest, Fargesia under gap of Dark Coniferous...