Analysis Of The Relationship Between The Availability Of Cadmium In Soil And The Cadmium Content In Rice

Large of heavy metal pollutants had been released into the environment with the rapid development of industry and agriculture in our country, the heavy metal cadmium is a much serious pollution among of pollutants. There are more than 13300 hectares of arable land areas had been polluted by cadmium, which lead to 50 thousand tons of "cadmium rice" every year. So the reduce of cadmium content in rice is more important to rice production of our country.But so far, it is lack of in-depth research and systematic evaluation that products which can reduce the cadmium affect the availability of cadmium in soil and the cadmium absorption of rice. In this study, we use three different chemical reagents(NH4Cl, CH3COONH4, EDTANa2)which have affinity with cadmium ions and three different passivation fertilizers( silicon potassium calcium magnesium duplicate fertilizer, alkaline granular fertilizer, Jinwuzong biologic fertilizer)to explore their influence on the cadmium content in water extract of soil and the cadmium absorption of rice. The purpose is to provide the theoretical basis and technical support for agricultural production related to the cadmium reduction. The main results are as follows:1、The analysis of four tested soils’ physical and chemical propertiesThe four tested soils’ physical and chemical properties are, A1: the total cadmium content is 0.18mg/kg, the available cadmium is 0.098mg/kg, pH 6.12; A2: the total cadmium content is 0.5mg/kg, the available cadmium content is 0.2mg/kg, pH 7.17; A3: the total cadmium content is 0.56mg/kg, the available cadmium content is 0.428mg/kg, pH 6.21; A4: the total cadmium content is 0.68mg/kg, the available cadmium content is 0.268mg/kg, pH 7.06.2、The influence on the cadmium content in water extract of soil with different cadmium affinity materialsCompared with the control, alkaline granular fertilizer can reduce the cadmium content in water extract of soil, all of other treatment can lead to the increase of the cadmium content in water extract of soil. For example, in the soil of 0.56mg/kg’s and 0.68mg/kg’s total cadmium content, the cadmium content in water extract of soil of the control is 0.2μg /L and 0.83μg /L, the cadmium content in water extract of soil of alkaline granular fertilizer’s treatment is lower than lowerlimit of detection of 0.1μg /L, the cadmium content in water extract of soil of EDTANa2’s treatment is 700 times and 265 times of the control, NH4Cl’s is 50 times and 28.92 times, Jinwuzong biologic fertilizer’s is 65 times and 20.48 times, CH3COONH4’s is 25.5 times and 19.28 times, silicon potassium calcium magnesium duplicate fertilizer’s is 2.8 times and 1.93 times.3 、 The influence on the cadmium content in rice with different cadmium affinity materialsLow cadmium absorption variety Xiangwanxian 12 and high cadmium absorption variety G283 were planted in four soil of different cadmium content. Compared with the control, the application of NH4 Cl, CH3COONH4 can increase the cadmium content in rice’s root, stem leaf, chaff and grain significantly, All of the application of EDTANa2, silicon potassium calcium magnesium duplicate fertilizer, alkaline granular fertilizer and Jinwuzong biologic fertilizer reduce the cadmium absorption of rice. The effect of alkaline granular fertilizer and Jinwuzong biologic fertilizer is better and they have no negative influence on the growth and fruiting trait of rice.4、the comparison of the cadmium absorption characteristics between two different rice genotypesThe cadmium content of Xiangwanxian 12 is lower than the cadmium content of G283 in the same organs in all treatment. It is especially obvious in the root of rice. The main reason of low cadmium accumulation in Xiangwanxian 12 may be the low absorption of cadmium in root. In four soil, the cadmium content of Xiangwanxian 12’s grain don’t exceed bid in all treatment. In the soil of 0.56mg/kg’s and 0.68mg/kg’s total cadmium content, the cadmium content of G283’s grain can exceed bid. Compared the cadmium content in different organs of rice, it is concluded that the root is the main organ which accumulate cadmium. The relationship of these organs which accumulate cadmium is: root > stem leaf > chaff > grain. And the difference of the cadmium content of rice’s chaff and grain is not obvious.