Effect Of Organic Fertilizer On The Effect Of Passivation Of Clay Material On Cadmium - Contaminated Vegetable

With the rapid development of industrialization and urbanization, a lot of heavy metal pollutants are discharged into the environment through high intensity of human activities, resulting in large area of farmland soil is polluted by heavy metals such as cadmium (Cd) and so on, which is a potential threat to crop yield and quality, ecological environment and human health. Therefore, remediation of soil heavy metal pollution become prominent in academia at home and abroad. Remediation technology has been widely studied and applied due to the high repair rate, high efficiency, and simple operation in recent years. However, more attention is still needed for the effect of organic fertilizers on the remediation of Cd contaminated soils, livestock and poultry manure which is rich in organic matter and N, P and other nutrients is widely used in agricultural production, the effects and mechanism of different kinds of organic materials are not the same. In this paper, pot experiment and field experiment were conducted to evaluate effects of adding chicken manure on soil pollution remediation effect of Cd passivation and soil enzyme activity in first test. Secondly, pot experiment was conducted with manure, pig manure and cattle manure in the remediation of sepiolite and attapulgite to evaluate the Cd content in edible part of Lactuca sativa L., soil available Cd content and soil available nutrient content after harvesting the crops, and a further discussion is necessary for the effect and mechanism of organic materials on the content of heavy metals in soil and plants. The experimental results are as follows:1. Pot experiments were conducted to investigate the effects of chicken manure on stabilization remediation of Cd contaminated soil and soil enzymatic activities. The results showed that the applying chicken manure under the stabilization remediation process using sepiolite could significantly reduce the concentrations of Cd in edible and root parts of rape in contrast to treatment with sepiolite, decreasing by 14.7%-26.0% and 6.7%-23.7%, respectively. Adding low levels of chicken manure can significantly increase the soil pH. Different treatments have a certain impact on soil enzyme activities, the addition of chicken manure significantly increase soil catalase, urease by 18.2%-30.3% and 8.2%-18.6% compared with the sepiolite soils. Adding chicken would decreased soil sucrose in different degrees compared with sepiolite treatment, low dose and high dose of chicken manure under passivation repair decreased soil sucrose by 27.9% and 28.5%, respectively.2. The field trials showed that the applying chicken manure under the stabilization remediation process using sepiolite could significantly reduce the concentrations of Cd in edible and root parts of rape in contrast to treatment with sepiolite, decreasing by 2.0% and 3.0%. Manuring under the stabilization remediation also significantly reduce soil available Cd content, the sepiolite treatment decreased soil available Cd content by 9.4% than the control, while the S+M treatment was reduced by 10.3%. Compared with the control, soil catalase and urease content were increased by 7% and 8.6% using single passivation remediation, by 36.5% and 22.2% adding chicken manure under passivation repair. The sepiolite treatment significantly increased the soil sucrose by 58.9% compared with the control, soil sucrose of the single application of chicken manure were decreased by 22.7%, and soil sucrose of adding chicken manure were increased by 5.5%.3. Indoor experiment showed that the clay material reduced Cd concentration of edible parts of lettuce by 5%-4%, compared with the control, while adding chicken, pig and cow dung after immobilization reduced Cd content in edible parts of lettuce by 4%-31%, 29%-38% and 23%-44%, respectively. Effect of Organic Substances on soil available Cd content is decreasing generally, also give rise to an increasing trend in soil pH. Compared with the control, the single passivation treatment has no significant effect on soluble sugar in Lettuce, and in addition to A+FD2, the treatment of adding manure increased soluble sugar in Lettuce conten by 2.3%-44.3%. In the clay material immobilization, then applying a variety of livestock manure, increased the soil basic nitrogen, available phosphorus and potassium contents significantly.