Study on Influencing Factors of Farmland Soil Heavy Metals in Central Yunnan Province

The soil heavy metals and physical and chemical properties from agricultural land in central Yunnan province were measured.The relationship analysis of soil type,altitude distribution,physical and chemical properties and soil heavy metals indicated that:(i)The heavy metal content of agriculture soil in central Yunnan province did not reach the maximal residue limit(GB15618-1995),and the heavy metals content in red soil was higher than that in other types.(ii)The content of cadmium changed slightly with altitude,the content of heavy metals in other soil with altitude varied greatly.(iii)Soil heavy metals was positively(P0.01) related to clay content.Along with the clay content increasing,the content of soil heavy metals became higher.(v)There was a positive correlation between pH,available manganese and heavy metals,and there was a negative correlation between exchangeable calcium and magnesium and heavy metals.