Effects Of Municipal Sludge And Compost On Uptake Of Cd And P In Potato Under Cd Treatment

Long-term application of municipal sludge to agricultural soil could lead to the problem of heavy metal accumulation in soils.In this study,to investigate the improvement effects between municipal sludge（MS）and municipal sludge compost（MSC）on fertility and other quality of loess,pot experiments were carried out by cultivating potato（Solanum tuberosum L.）under nine different levels of Cd treatment,simulating the accumulation of Cd in soils by long-term application of MS or MSC.The effects of MS and MSC on the growth of potato were examined;the uptake of Cd and P in potato was also determined.The main results and conclusions were presented as follows.（1）Both MS and MSC improved the fertility of the soil as well as potato growth,and MSC improved potato growth with higher rate than MS.The growth of potato was stimulated under lower Cd treatments（especially at Cd1.0）,and the stimulation of growth gradually declined with increasing Cd concentration in the soil,and even inhibition of growth in roots and stems were observed in this study（Cd6.8^Cd12.0）.（2）Given increasing Cd concentrations in the soil,Cd concentrations increased in each part of potato plants,and the sequence of Cd concentrations in potato plants was stem≈root>peel≈tuber.For the nine Cd levels studied in this study,only those treated with Cd0 and Cd0.5 in the tuber did not exceed safety limit(0.1 mg kg^-1 FW for tuber vegetables according to China national standards for food safety inspection).（3）Under the same Cd treatment,both the chemical extractions of Cd in the soil and Cd contents in each part of potato plants were in the sequence of S2>S3>S1（S1:control;S2:application of MS;S3:application of MSC）.The results suggest that the bioavailability of Cd could be significantly increased by application of MS,while the bioavailability could be increased slightly by MSC.（4）Under the same Cd treatment,the sequence of available phosphorus in the soil was S2>S3>S1.The result indicates that MSC is more beneficial than MS in uptake of P in potato plants.（5）Pearson’s correlation coefficient showed that the available P concentrations in the soil and potato Cd concentrations were negatively correlated with total Cd in the soil（P<0.01）.The results suggest that the Cd exert complicate negative effects on the uptake and translocation of P in soil-plant system.