The Research On Soil Particle Fractal Dimension In Huangshan City

The characteristics of Huangshan City is of the complex topography, variousgeomorphic units and a variety of land use types. The thesis, from different angles ofthe topography and land use types, selectes28soil profiles, using fractal models tocalculate the fractal dimension of soil particles and analyzes the fractal characteristicsof the soil particles. And the following conclusions:(1) The fractal dimension in Huangshan City ranges from2.6580to2.8174(Pei-Ling Yang France), and from2.8653to2.9362(AR method). The minimum ofthe fractal dimension is in the15thsoil profile in which the terrain is mountainous.The maximum of the fractal dimension is in the20thorchard soil profile in which theterrain is hilly. The mean value of soil dimension reaches2.7502(Pei-Ling YangFrance) and2.9064(AR method).(2) Huangshan City is of different terrains, just as the mountains, hills and plains(terraces, mountain basin). The fractal dimension of soil particles in A layer isdifferent under different terrain conditions. Soil fractal dimension in mountain rangesfrom2.6580to2.8020(Yang Peiling France), from2.8653to2.9278(ARmethod);soil fractal dimension in hilly areas ranges from2.6760to2.8174(YangPeiling France), from2.8743to2.9362(AR method);soil particle fractal dimensionin plains area ranges from2.7220to2.7955(Yang Peiling France), from2.8956to2.9261(AR method).The change of soil particles fractal dimension in mountainousand hilly areas is big, relatively small change of soil particles fractal dimension existsin the ground land. From the mountains and hills to plains, the mean value of soilparticle fractal dimension shows a gradual upward trend. The main reason is thedifference on the degree of vegetation cover in the three terrains soil erosion.(3) Huangshan City is of avariety of land use types, mainly just as farmland,woodland, orchards and grassland. There is a big difference of soil particles fractaldimension in A layer under different land use types. The soil particles fractaldimension of farmland is between2.7220and2.7927(Pei-Ling Yang France), from2.8956to2.9261(AR method); soil particles fractal dimension of woodland isbetween2.6580and2.8020(Pei-Ling Yang France), from2.8653to2.9276(ARmethod); soil particles fractal dimension of Orchard ranges from2.6760to2.8174(Pei-Ling Yang France), from2.8743to2.9362(AR method); soil particle fractal dimension of grassland ranges from2.6548to2.7882(Pei-Ling Yang France),2.8649~2.9226(AR method). The changes of soil particle fractal dimension in woodlandsoil and orchard soil is by a big margin, relatively small change of soil particles fractaldimension exists in the farmland soil and grassland.From arable land and woodland to orchard and grass, the mean value of surficialsoil particles fractal dimension generally shows a downward trend. It’s mainly due tothe difference on the degree of vegetation cover and soil erosion under different landuse types, which leads to the difference of the loss of the clay in the soil erosionprogress. The higher clay content loss,the more coarse soil particles are, the smallersoil particles fractal dimension. So the degree of vegetation coverage can be effectivein improving the texture of the soil, thus affecting the size of soil particles fractaldimension.(4) On the vertical profile, as the soil depth increases, the percentage of physicalclay and clay in the soil of arable land, grasslandand woodland increase at first andthen decrease, but the rate of increase or decrease are different. While the orchardshows a continuous increase. That demonstrates that the degree of soil coverage willinevitably lead to soil erosion in different levels, and thus affects the difference onsoil texture, structure and other physical properties. By analyzing soil profiles indifferent land use types, we can know that small changes of the fractal dimension ofsoil particles exists in the soil profile, and increases as the increasing soil depth;fractal dimension of the woodland and orchard soil particles showed a decreasingtrend after the first increase as the increasing soil depth, but the change margin oforchard is less than that in woodland; fractal dimension in grass deep soil is smallerthan that in the surface of soil particles. In the surface soil, the soil particles fractaldimension of arable is minimum.(5) The relationship between the fractal dimension and particle size of soilparticles are closely related. The more fine sand content in arable land and orchardsoil particles, the smaller the fractal dimension; and the more coarse silt content inthe soil particles, the smaller the fractal dimension; and the more coarse sand contentin the grassland soil particles, the smaller the fractal dimension. Furthermore, there isthe best correlation between fractal dimension and the content of clay that particle sizeis less than0.001mm. So the thesis establishes the mathematical model of therelationship of the fractal dimension and the clay, and does the experimentalverification for the model.(6) The fractal dimension and soil organic matter content soil particle of issignificantly positively related. The higher organic matter content, the greater thefractal dimension of soil particles.(7) The fractal dimension can reflect the situation of soil fine particulate matter and organic matter losses, and then reflect the degree of soil erosion. Therefore, wecan use the soil particles fractal dimension instead of soil particle size composition ofsoil to characterize the degree of erosion, and thus reflect the soil erosion in thisregion.(8) There is a linear correlation between the parameters that describes the soilclay conten, mean weight diameter, geometric mean diameter, uniformity index Iu andparticle size distribution and fractal dimension. Therefore, the size distribution andfractal dimension can be used as an indicator of the evaluation of soil textureconditions.(9) There is a little difference on the calculation results of the surface of soilparticles between using YANG Pei-ling method on AR method for computing, on thewhole, Pei-Ling Yang method is less than the AR method. Using YANG Pei-lingmethod to calculate the fractal dimension, that shows the particle size distributionfractal dimension number, and its fractal science significance is not very obvious,while the AR method has obvious fractal theory significance, its fractal dimensionnumber is refers to the particle surface fractal dimension number, so using the ARmethod to do the differentiation for the quantitative characterization of soil texturewill be better.