Study on Quality Evolution of City Soil and Effect of Soil Amelioration by Organic Fertilizer Application

By method of comparison and analysis, the evolution process of soil quality and its evolution reason from natural soil to agricutural soil and city soil, as well as the effect of organic fertilizer application on the availability of soil quality were studied. The results showed: There were apparent changes of physical properties and nutrition content in the evolution process of city soil quality. The volumetric weight of natural soil(tessellated meadow soil) without the influence of human activities was the lowest, that of old plough land for agriculture was lower, that of forest soil was low, that of city soil was highest in four different types of soils. That at the depth of 20~40cm soil layer for city planting land was increased by 17.7%~43.7% and 35.4%~93.9%,the total porosity was decreased by 1.9%~13.0% and 34.1%~52.4%,saturation capacity was decreased by 16.6%~39.5% and 60% respectively, in comparison with that of forest soil and agriculture soil. The organic matter on the surface soil of city lawn land and city planting land was decreased by 86.6% and 82.9% as compared with old plough land for agriculture, decreased by 96.1% and 95.0% in comparison with natural soil. The total nitrogen and rapidly available nitrogen of city soil at the depth of 0~60cm soil layer was decreased. The total phosphorus and available phosphorus were increased by 70.1%~117.4% and 173.5%~222.1% as compared with that of forest soil, 44.9 %~161.2% and increased by 98.4%~694.4% in comparison with agricultural soil. This result showed that there was apparent ultrophication of phosphorus in city soil. There was not apparent change of pH value within the depth of 0~60cm soil layer in the process of soil evolution. Fertilization for city soil can reduce volumetric weight of the soil, improve soil air conductivity, raise soil water content, regulate and improve pH value to make the soil neutralism. Meanwhile, organic matter, total nitrogen, available nitrogen, total phosphorus and available phosphorus were improved.