Effects Of Magnesium, Manganese, Activated Carbon And Lime On Availability Of Soil Cadmium And Uptake Of Cadmium By Wheat

In recent years, with the rapid development of industry and agriculture, environmental pollution becomes increasingly serious. It harms human’s health seriously and causes damage to the environment especially the heavy metal elements pollution. Cadmium is one of the most toxic heavy metals in the environment, It is widely concerned for its wide pollution area and large amount of involving crops species and the problem of risking human and animal health via polluting agricultural products in food chain In agricultural production, poor farming pattern, land use and farmland management can significantly increase the available Cd concentrations in soil and the amount of Cd uptake of crops, especially when fertilizer categories and fertilization method are tactless, finally lead to increasing the probability of exceeding the standard of Cd concentrations in agricultural products Therefore, It is significantly great for China’s food security to study on the factors which affect the soil Cd availability in Cd contaminated soil and the effects of different materials to Cd validity and uptake of crops.Different fertilizer to the Cd polluted soil would affect the physicochemical properties of the soil adjacent to fertilizing point, thus affected the soil Cd morphology and Cd uptake of plants. In the past studies, some of domestic and overseas authors have studied on Mg, Mn, lime and other substances, but the studies on the amount of different materials and the interaction among them were rarely reported. Therefore, this study used the cadmium polluted soil, with magnesium sulfate, manganese sulfate, active carbon and lime as research material, to research on the effects of dosages of magnesium sulfate, manganese sulfate, active carbon and lime and the interaction among them on the availability of cadmium in soil through culture experiment. At the same time discussed the effects of magnesium sulfate, manganese sulfate, active carbon and lime dosages as well as the interaction among them on wheat growth and cadmium uptake of crops, to explore new materials and methods for soil cadmium pollution control. The primary conclusions are as follows:1、Results showed that Mg, Mg, AC and lime significantly affected soil pH and concentrations of available Cd. Soil pH was remarkably enhanced with addition of lime and positively correlated to its application rates, while soil pH was significantly reduced with addition of Mg, Mn or AC and negatively correlated to its application rates. No matter these materials were added alone or in combination, concentrations of soil available Cd were reduced or significantly reduced. The effects of these materials on depressing soil available Cd concentrations followed an order of lime>Mn>Mg>Ac when applied alone, and an order of lime+Mn+Mg>Mn+Mg>lime+Mn>lime+Mg>lime+AC when used in combinations. The effect of Mg(OH)2on reducing soil available Cd was superior to Ca(OH)2.2, application of appropriate amounts of magnesium sulfate (Mg), manganese sulfate (Mn) or in combination with lime could promote wheat growth and seed yields, while addition of lime alone or in combination with activated carbon significantly reduced wheat seed yield. Application of Mg significantly reduced concentrations and uptake of Cd in wheat seeds and straw and positively related to Mg rates. Concentrations and uptake of Cd in wheat seeds and straw were effectively decreased by the lower rates of Mn but increased by the higher rates. Lime and activated carbon, no matter it was used alone or together, remarkably restricted Cd uptake by wheat, while Cd ratio of seed/straw tended to increase with lime rates. Folia spray of Mg was equally effective as incorporating Mg into soil on restricting Cd uptake by wheat but a significant depressing effect on Cd uptake by folia spray of Mn over soil application of Mn was observed. Whether Mg and Mn or lime, Mg and Mn were used together produced pronounced positive interactions on depressing Cd concentrations and uptake in wheat seeds and significant restrictive effect on Cd transfer from straw to seeds as well.