Area Variation Of Soil Characteristics In Vegetable Plots Of Yellow Soil And Its Impact On The Quality Of The Vegetables In Guiyang

This paper studied regional variability of vegetables soil physical and chemical nature about the surface soil, the soil hearts,the rhizosphere and non-rhizosphere soil in the yellow soil in Guiyang city. And it analyzed contents of heavy metals in soils and the relationship of them in vegetables and soil, and evaluated contamination by heavy metals in vegetables and soil, and discussed the main reasons for the regional variations of the soil properties and their effects on the environment.The main conclusions was as follows :(1) Most vegetables surface soil was heavy loam,and there existed conspicuous differences on the soil physical clay, soil capillary porosity and non-capillary porosity in the different regions, but the difference of other soil physical properties were not obvious. The vegetable soil assumed the neutrality or the weak-acid, and the difference in areas was not big. There was the trend that CEC(Cation exchange capacity) in vegetable soil in suburb was higher than that in urban and rural area, which its mean value was 17Cmol(+)/Kg above, belonging the superior level on holding fertilizer. The content of soil organic matter, total N and hydrolyzed N in urban area was higher than that in suburb and rural area, reaching significant variation. The mean value of soil organ matter in urban area reached on 117.4g/kg, which was three times of it in rural area. And the content of Potassium element in vegetable soil was the most in rural area,and sencondly was suburb.(2) Most indicators of the soil properties in rhizosphere were more than non-rhizosphere.but the content of P and K in the soil rhizosphere were more than non-rhizosphere .(3) Most indicators of the soil properties in surface soil were more than heart soil in vegetable soil in Guiyang,and it sames to the different areas, showing that the soil nutrient content and other characteristics of the surface soil significantly enriched.(4)The levels of heavy metals in soil in urban area were the most, but not have significantly different in the three areas. Hg was the most main contaminant, followed by Cr and Pb,and As, Cd are not obvious in 3 area; The multi-factor of heavy metal pollution in the heart soil was same to the surface soil. With the exception of Pb pollution of soil in urban reached a mild, Cr achieve alert, the one-pollution index of in the rest of heavy metals was less than 0.7, indicating the heart soil had not been contaminated.(5) The levels of heavy metals in vegetables were most in urban area, but not had significantly different in the three areas. Hg and As were the main contaminant in vegetables and Cd, Cr are not exceeding.(6)There were also significant correlations on Pb, Cr, Cd in vegetables. However, the content of heavy metals in soil and vegetables were not statistically significant correlation.(7)The CEC and pH affect that Cr and Hg were absorbed in vegetables, but which not affected on Pb,Cd and As. The contents of As, Hg, and Cd in vegetable were high if the content of organic matter in soil is high, noting the increase of soil organic matter will affect that As, Hg, and Cd is absorbed in vegetables. Soil available K was not much impact on vegetable absorbing heavy metals. But P had some impact on vegetable to the absorption of heavy metals. The heavy metals As addition, the alkali - soluble nitrogen had a certain influence on other vegetables absorbing other heavy metals .