The Soil Particles Fractal Characteristics And Nutirent Status Of Typical Land Use Types In Yimeng Mountain Areas

To investigate different slope and different land use types in Yimeng Mountain soildegradation, select Mengpo small watershed in Yiyuan, measure correlation and changes intypes particles, fractal economic dimension, soil physical properties and nutrient content atdifferent slopes, terrace economic forest, grassland and Windbreaks. The main results showthat:1. The particle composition and texture of soil in research areaThe soli of research area has thick bone sandy physical properties, in different land use,soil sand content up to65.99%~77.38%, while the lowest is silt and clay that content1.44%~5.06%.According to the U.S. Department of Agriculture classification system it belong sand.Multiple comparison analysis indicates that, Windbreaks, slope and grassland have significantdifference in the content of coarse sand (1~0.5mm) and fine sand (0.25~0.1mm); slope,terrace economic forest, grassland and Windbreaks land have significant difference in thecontent of fine sand (0.25~0.1mm); the soil sand content increased with the increase ofslope; the loss of silt and clay is strengthened, that resulting uniformity of soil particlesdecreased heavier soil texture coarse. Performance for farmland soil capacity big, porosity,capillary porosity decreases and the capillary porosity increased, the ability of keep water inthe soil is decrease.2. The fractal characteristics of soilFractal dimension of soil particles descending order are ecological forest land, grassland,terrace economic forest and slope. The weight fractal dimension of soil particles is2.03~2.28in different land use types, and the average value is2.16; the volume fractal dimension of soilparticles is2.33~2.53, and the average value is2.44; the pore fractal dimension of soilparticles is2.72~2.87, and the average value is2.81. Fractal dimension of soil particlesdecreases with the increase of slope. Its size has very significant positive correlation with soilsilt and clay content. Fine grained material content is higher, the higher the soil fractaldimension. Soil weight fractal dimension, volume fractal dimension and pore fractaldimension have significant positive correlation. That can better reflect the structuralcharacteristics of soil.Multifractal spectrum width size descending order is Windbreaks, grassland, terraceeconomic forest, slope. Slope, derelict land and Windbreaks have the most obvious differencein change, so the Windbreaks and derelict land have the greatest influence on distribution of soil particle size. Multifractal fractal is better than a single fractal which reflects differentgraded granules in different regional features.3. The nutrient status of soilChanges in soil nutrient content with the land use types and slope changes areinconsistent, organic matter content in different land use descending order are Windbreaks,grassland, and terrace economic forest, the mean value are17.35,17.05,16.11and12.59,respectively. Rapidly-available potassium content descending order are Windbreaks, grassland,terrace economic forest and slope, the mean value are77.62,65.00,45.12and12.59,respectively. Effective phosphorus content descending order are slope, terrace economic forest,Windbreaks and grassland, the mean value are124.44,108.13,78.44and73.33, respectively.Hydrolysis nitrogen content descending order are grassland, slope, Windbreaks and terraceeconomic forest, the mean value are36.67,32.67,32and25, respectively. Effectivephosphorus content have a significant difference between slope and other3fields in multiplecomparison analysis. Slope also has a significant difference with terrace economic forest inhydrolysis nitrogen content. Soil organic matter content is nothing to do with sand content,but about silt and clay content. Soil nutrient content decreases with increasing slope.Windbreaks organic matter content are more than27.44%and1.73%compared with the sameslope terrace economic forest and slope in angle of twenty degrees. The reason that littledifference between Windbreaks and slope in organic matter content is to increase organicfertilizer when artificial cultivation in low slope.4. The correlation between soil physical properties and soil fractal dimensionAverage of soil bulk density is1.47, there is significant difference between terraceeconomic forest and Windbreaks in soil bulk density (P <0.05). The mean of the averagemoisture content, total porosity, noncapillary porosity and capillary porosity is5.22%,33.29%,10.33%and22.96%, respectively. There is significant difference between slope and grasslandin total porosity of soil, and also Windbreaks is (P <0.05). The soil bulk density of slope andterrace economic forest increases with the increase of slope, soil water content of slope reducewith the increase of the slope, with the increase of slope, noncapillary porosity increase andcapillary porosity reduce in slope and terrace economic forest. With the increase of slope,noncapillary porosity reduce and capillary porosity increase in grassland and Windbreaks.Mass fractal dimension of soil particlest and volume fractal dimension, which arenegative correlation with bulk density and soil moisture content, but they are positivecorrelation with total porosity, noncapillary porosity and capillary porosity. Soil pore fractaldimension is negative correlation with soil bulk density, but it is positive correlation with soil moisture content, total porosity, noncapillary porosity and capillary porosity.