Study On Migration Of Phosphorus, Potassium And Heavy Metals In Municipal Sludge Compost Amended Loess-potato System

The disposal of the growing municipal sewage sludge has become a big problem to the scientific community and the governments of world.With the inherent advantage,soil reclamation with sewage sludge became the reasonable and effective one of all disposal measures.In the application of sewage sludge to soil,the migration and enrichment of heavy metals were the focus issue of the scientific community.For this study,a potato pot experiment were carried out investigating the migration and biological effect of heavy metals?cadmium,lead,copper,zinc and nickel?and plant nutrients?phosphorus and potassium?in the municipal sludge compost-amended soil.The results showed:1.The municipal sludge compost?MSC?improved the soil fertility of loess and therefore improved the growth of potato.The dry weights of stem and tuber increased by 183.4%and 232.8%,respectively.The MSC also increased the activity of P and K in amended soils,and increased the potato uptake of Pand K.The concentrations of P and K in each parts of potato increased by 94.9%and 252.3%.2.The MSC addition obviously increased the active fraction concentraions and proportions of heavy metals in amended soil,and therefore increased the concentrations and BCF of heavy metals in root,stem,tuber and peel.The DTPA extraction was the highest in phytoavailability,and the phytoavailability was affected by soil organic matter,DOC,pH and carbonate3.The Cd addition obviously increased the active fraction concentraions and proportions of Cd in amended soil,and therefore increased the concentrations and BCF of Cd in potato plant.When the MSC ratio was not more than 2.0%,CH₃COOH extraction was the highest in phytoavailability;but when the MSC ratio was more than 2.0%,DTPA extraction was the highest in phytoavailability.4.The Cd addition decreased the P activity?DP concentration decreased by 34.8%?but increased the K activity?DKconcentration increased by 29.6%?in amended soils.The Cd addition decreased the potato uptake of P and K in amended soils.5.When the MSC ratio was not more than 2.0%,CH₃COOH extraction had important impact on DP,DK,and potato uptake of P and K;when the MSC ratio was more than 2.0%,DTPA extraction had important impact on them.6.The MSC could inhibit the Cd activity increase,the P activity decrease,the potato uptake of Cd increase,the potato uptake of P and K decrease in amended soil caused by Cd addition.Our results suggested that the MSC improved loess property,and improved potato growth and uptake of P and K,but it increased heavy metals activity in amended soil and increased poatao uptake of heavy metals.This provided favorable condition for plant restoration of amended soil.Cd was the higher potential hazard heavy metal in amended soils,and it needed special attention.