Effects Of Heavy Metal Residue In Manure On Agricultural Products And Soil Environment

In this thesis, the accumulation of heavy metals in litter of fermentation beddings in swine farm, the effects of manure on soil environment and agriculture products quality, accumulation of Cu and Zn in soil were studied, and the risk of applying biogas slurry on heavy metals accumulation were studied. The main results are as follow:1. Monitoring study on the Accumulation of Copper and Zinc in Litter of Fermentation Beddings in Swine Farm. Two typical pig farms with pig-on-litter system in Zhejiang province were selected and monitored to discover the rules of heavy metals accumulation in litter. The litter in different buildings were sampled and the concentrations of total nitrogen, total phosphorus, Cu and zinc were analyzed in this study. The results showed that accumulations of Cu and Zn were affected significantly by the service time of litter, Cu and Zn concentrations in feed, and breeding density, with the service time as the most important factor. The litter in piglets and grow-finish rooms can be used no longger than 31 and 48 months according to the Chinese national standard. The TN and TP concentrations in litter were lower than the manure. The litter should be treated and sorted before used as fertilizer.2. Effect of chicken manure on eggplant quality and the accumulation of Cu and Zn in soil. Pot experiments were carried out to study the effect of chicken manure on the yield and quality of eggplant and accumulation of Cu and Zn in eggplant and soil, and the adequate application rate of chicken manure was discussed. The results showed that the yield of eggplant and the content of protein in different organs increased significantly with the application rates increased when it was below 18.8 g/kg (32 t/a). In addition, the yield and the concentration of protein were highest with the treatment 18.8 g/kg. The yield was decreased and the difference among the protein concentrations was insignificant with applying excessive manure. The accumulation of copper and zinc in stem was higher than that of fruit while increased the application rate. Zinc concentration in stem significantly increased when the application rate increased, and that in fruit were almost the same. Concentrations of copper, zinc and total nitrogen in soil were increased apparently when the application rate increased. If the application rate exceed 9.9,17.5,9.2 g/kg (17,30,16 t/a), soil had risk of copper, zinc and total nitrogen accumulation. In order to improve the yield and quality of eggplant and decrease the environmental risk, the application rate should be in the scope of 16 t/a-32t/a.3. Effect of biogas slurry on sweet potato quality and accumulation of Cu and Zn in soil. Field experiment were carried out to study the effect of biogas slurry on the yield and quality of sweet potato and the heavy metal accumulation in sweet potato and soil. The results indicated that application of biogas slurry significantly increased the yield and improved the content of protein in different organs. The yield were highest with the treatment 30t/a. The content of protein in different organs decreased when application rate exceeded 10 t/a. The uptake of Zn by stem and fruit decreased firstly and then increased with the applying rate increased. However, the copper concentration in sweet potato was changed non-significanlty. The effect of biogas slurry on the uptake of Cu and Zn by different organs differed. If the application rate exceed 6.1,7.6.10.7 t/a, it might pose a risk of copper, zinc and total nitrogen accumulation to soil environment. In order to improve the yield and quality of sweet potato, and decrease the environmental risk, the application rate should be in the scope of 6.1t/a-10t/a.4. Heavy metal pollution and risk assessment of appling biogas slurry livestock breeding system. Soil samples were collected around the two typical farmlands for risk assessment of heavy metals, and agriculture product were collected for analyzing the copper, zinc and nitrogen concentration. The results indicated that the concentration of Cu, Zn in pear garden soil exceeded the standard. Partial field around the two farm had a light Cu and Zn accumulation risk when the biogas slurry applied excessive in a long-term time. The mode of Wangqiang and Shunwang can be used no longger than 17 and 9 years. Thus, the two farms should cut down the application rate of biogas slurry.