Effects Of Organic-inorganic Fertilizer From Chicken Manure On The Accumulations Of Heavy Metals In Soil-plant System

The fertilizer of the livestock and poultry manure could solve environmental problems. It is also the solutions to promoting the sustainable development of the agricultural cycle. This study would obtain the effect of the different fertilization treatments for the soil and heavy metal. It would be come true by using the field trials with the organic and inorganic fertilizer from chicken manure. With the Cumulative index (Igeo) and potential ecological risk index method (EI), this study would evaluate the soil pollution situation and the potential hazards for heavy metal in the fields. In addition, the pollution evaluation of heavy metal in crop grain would be obtained with Single factor index method. Main conclusions are as follows:(1) The dynamic change of soil heavy metalIn the study area, the heavy metal content in the topsoil was higher than that in20-40cm soil layer, and the heavy metal contents in the topsoil and20-40cm soil layer were both lower than the environmental quality standard limits. As a reference to the soil heavy metal content before the rape-planting, the heavy metal content in topsoil increased for the rape mature, while that for the rice maturity decreased after the different treatments of the fertilization. After rape-rice rotation, compared with the unfertilized control, Cd and Pb contents in topsoil with different fertilizer treatments had no significant difference. Under three kinds of organic and inorganic fertilizer treatment, Cu and Zn in topsoil were significantly higher than those of CK (P<0.05), andincreasedby6.2-39.9%and2.3-37.6%respectively. The soil Zn content under three treatments was significantly lower than that of the inorganic fertilizer (IF) and organic fertilizer(OF) treatments(P<0.05). The Cu in topsoil had no significant variation, In20-40cm soil layer with the different fertilizer treatments, Cu content was only significant higher than that in CK(P<0.05), while Cu content in the soil had no significantly variation among different fertilizer treatments.Compared with the heavy metal content in the topsoil before the wheat planting, the content in the top soil for wheat and corn maturity increased under the different fertilization treatments. As the soil depth increasing, the heavy metal content in20-40cm and40-60cm soil layer decreased progressively, and the content were lower than the environmental quality standard limits. After one year of the Wheat-Corn rotation, the Cu, Pb and Zn contents in topsoil with different fertilizer treatments were higher significantly than those in CK (P<0.05).Under three kinds of organic and inorganic fertilizer treatment, Cu, Pb and Zn in topsoil were significantly higher than those in CK (13-39%,7.2-33.4%,49.8-102%). The soil Cu under three treatments was significantly lower than that in OF treatment by12.3-15.3%. The soil Pb and Zn contents were significantly lower than those in the IF and OF treatments. In20-40cm soil layer with the different fertilizer treatments, Cu, Pb and Zn contents were significantly higher than those in CK (P<0.05), and the variation of the content was less than that in the topsoil. The soil heavy metal content in40-60cm soil layer had no significant variation.(2) Evaluation of soil heavy metal pollutionThe evaluation of the Cumulative index method showed that all the fertilizer treatments of soil Cd belonged to moderate pollution on the basis of background values of soil element. It was due to the lower content of soil background values which compared the environment quality standards. However, all processing were not contaminated soil, but the Cd was still cumulative risk basing on the secondary standard for soil environmental quality evaluation standard.The valuation with the Potential ecological risk index of single factor showed that soil Cu, Pb, and Zn in farmland all belonged to minor damage, and Cd reached the intensity of hazards on the basis of background values of soil elements. The soil Cd, Cu, Pb and Zn with different treatments belonged to minor damage on the basis of soil environmental quality secondary standard content. The evaluation by multiple factor potential ecological risk assessment showed that the dangers of inorganic fertilizer on farmland soil heavy metal is greater than organic fertilizer and organic inorganic compound fertilizer.(3) Crop grain characteristic of heavy metal content and pollution conditionUnder the Rape-Rice crop rotation, the Zn content with the different processing only in rice reached significant level (P<0.05). Under three kinds of organic inorganic fertilizer treatment, the Zn content in rice increased significantly compared CK of12.2-26.6%, and lower significantly than that in OF treatment16.7-26.2%.Under the Wheat-Maize rotation, Zn content in the wheat and corn grain with different processing reached significant level (P<0.05). Under three kinds of the organic inorganic compound fertilizer processing, Zn content in wheat and maize grain increased significantly of5-68.4%, compared with CK, and reduced significantly of13.1-39.2%, compared with the OF processing.Grain crop pollution evaluation showed that the four kinds of crop seeds were not polluted by heavy metals. The influences of Cd and Pb in crop seeds were greater than Cu and Zn. The pollution levels of OF treatment for crop seeds were higher than other processing.