Study On Fractal Characteristics Of Soil Particles And Their Correlation With Soil Properties In Lowlands Of The Yellow River Delta

Soil particle-size distribution was one of the most important physical attributes due toits strong influence on soil hydraulic properties, soil fertility and soil erosion. The fractalcharacteristics of soil particles and their correlation with soil physical and chemicalproperties under different land use patterns in lowlands of the Yellow River Delta werestudied with the monofractal and multi-fractal theory and methods. The result showed that:（1） The difference of soil physical and chemical properties under different land usepatterns was significant. From the mean term, Soil pH value, conductivity and soil bulkdensity followed a consistent rule, Black Locust <European and American Poplar <Cotton<Waste Grassland, but soil porosity, non-capillary porosity, soil steady infiltration rates, soilorganic matter, total nitrogen, available nitrogen, total phosphorus, available phosphorusfollowed another consistent rule, Black Locust> European and American Poplar> Cotton>Waste Grassland. From the vertical soil profile, Soil pH value and conductivity of WasteGrassland surface soil were higher than deep soil, but other index of land use patterns wereon Contrast, this showed that Black Locust, European and American Poplar and Cotton hadmore obvious soil improvement effect, the surface soil quality was superior to the deep soil.The soil steady infiltration rates of Black Locust and European and American Poplar werehighest, the values were2.11mm·min^-1and1.82mm·min^-1, followed by Cotton, the value is1.57mm·min^-1, the lowest was Waste Grassland, the value was1.24mm·min^-1. These resultssuggested that the improved ability of forest land （Black Locust, European and AmericanPoplar） was higher than other land use patterns, but because of the different of species, theintensity and management goal, the improved results between the forest land had somedifferences. Cotton due to the long-term human activities, which could better improved soilstructure and soil quality. Waste Grassland coverage was low, long-term surface exposed,had seriously hampered the improvement of soil quality. （2） The difference of the monofractal dimension D under different land use patternsvaried greatly. Land use patterns had a significant impact on the composition of the soilparticles and particle distribution through the study of soil particle composition anddistribution of the frequency plot. The monofractal dimension D under different land usepatterns were different, expressed as Black Locust（2.6661） and European and AmericanPoplar（2.6617）, Cotton （2.5829）, followed by, Waste Grassland was minimum （2.4923）.From the vertical soil profile, monofractal dimension of Black Locust and European andAmerican Poplar decreased along with increasing soil depth, but the trend of Cotton andWaste Grassland were on contrary. Soil fractal dimension showed a linear correlation withthe soil clay, silt and sand content by regression analyzing of soil particle size fractaldimension and size of soil particles content, showed a positive correlation with the clay andsilt content, showed a negatively correlated with soil sand content, correlation coefficientswere above0.95.（3） The difference of the multi-fractal dimension under different land use patternsvaried greatly, fractal characteristics of soil particles was studied by multi-fractal method,and analyzed Rényi spectrum of soil particle size distribution. Rényi spectrum was typicalof anti-S-shaped decreasing function, and Multi-fractal parameters showed trends inD₀>D₁>D₂,This showed that all the soil particle size distribution was not evenly distributed,their multi-fractal analysis was necessary. The multi-fractal dimension （D₀, D₁, D₂, D₁/D₀）under different land use patterns were different, expressed as Black Locust（0.8396,0.7933,0.7598,0.9449） and European and American Poplar（0.8396,0.7858,0.7422,0.9359）,the Cotton （0.8268,0.7530,0.7251,0.9108）, followed by, Waste Grassland was minimum（0.8247,0.7499,0.7231,0.9096）. From the vertical soil profile, all fractal dimensions ofBlack Locust and European and American Poplar decreased along with increasing soil depth,but the trend of Cotton and Waste Grassland were on contrary. Multi-fractal dimensionshowed a linear correlation with the soil clay, silt and sand content by regression analyzingof soil particle size fractal dimension and size of soil particles content, showed a positivecorrelation with the clay and silt content, showed a negatively correlated with soil sandcontent.（4） By analyzing the soil fractal parameters with soil physical and chemical properties, monofractal（D）, multi-fractal（D₀,D₁,D₂,D1/D₀） showed a linear correlation with soilphysical and chemical properties, showed a positive correlation with soil pH value,conductivity and soil bulk density, showed a negatively correlated with soil porosity,non-capillary porosity, soil steady infiltration rates, soil organic matter, total nitrogen,available nitrogen, total phosphorus and available phosphorus.Soil particle fractal parameters could better reflect the soil structure properties, andanalyzed the quantitative relationship between the fractal parameters and soil physical andchemical properties in lowlands of the Yellow River Delta, and then they could better tokenthe influence and change of soil structure and soil fertility with different land use patterns,and it could provide a theoretical basis and technical guidance for land management anddevelopment in lowlands of the Yellow River Delta.