Effect Of Four Kinds Of Soil Conditioner On Reducing Cadmium In Rice And Application Analysis

The cadmium pollution of paddy soil in Guangxi is mainly moderate and mild,but the contaminated farmland is still producing rice grain,which is the potential risk of rice cadmium exceeding the standard.Therefore,to study the effect of soil conditioning agent on rice uptake and accumulation of cadmium,and to evaluate the effect of different soil conditioning agents on reducing cadmium content in rice,can provide data support and guidance for the safe production of rice in Guangxi.It has important practical significance and guiding value for cadmium pollution paddy soil treatment and grain security.In this study,the field plot experiment and the field demonstration test were used to study the rice production in Guangxi middle and low pollution rice fields.The effects of lime,commercial organic fertilizer and calcium magnesium phosphate fertilizer on the absorption and accumulation of cadmium in rice were discussed.The application of soil conditioner in cadmium polluted farmland was discussed.At the same time,the problems existed in the popularization and application of soil conditioner were combed with the production practice.The corresponding countermeasures are put forward.The main findings are as follows:1.The results of field plot experiment showed that the application of lime(T)and soil conditioner I(ST)can significantly increase the pH value of rice soil,and increase the maturity stage by 0.2 units.Applying soil conditioner I(ST),commodity organic fertilizer(C),commodity organic fertilizer + calcium-magnesia phosphate fertilizer(CM)can improve soil organic matter content and C and CM dealing with organic matter content of 9%.T,ST,C and CM treatment can reduce the content of cadmium in the soil effective state of rice at maturity stage,with the decreasing percentages of 17%,20%,24%and 25%respectively.Application of soil conditioner I(ST),commodity organic fertilizer(C),commodity organic fertilizer +calcium magnesium phosphate fertilizer(CM)can reduce the content of cadmium in fine rice,and the percentage of decrease is 13%,24%and 26%respectively.T,ST,C and CM can increase the average rice yield in the community.2.The results of field demonstration experiments at three test sites show that the application of soil conditioner I(ST)can improve the soil pH and organic matter of rice and reduce the content of soil cadmium in effective state.At tillering stage,the maximum pH value of soil was increased by 0.24 units and at maturity stage by 0.36 units.Soil organic matter content increased by 1.6?1.8g/kg.The effective cadmium concentration in soil decreased by 8.7%-23%.The application of soil conditioner I(ST)could reduce the accumulation of cadmium in rice,and the cadmium content in rice roots decreased by 3.1 to 15.3 percent in the mature stage.Cadmium content in stem and leaf decreased by 5.3%?17.3%at tillering stage and 0.02v0.38mg/kg at maturity stage.The content of cadmium in brown rice decreased by 31%?43.1%,and that of refined rice decreased by 20.5%?24.2%.3.There are the following problems in the promotion and application of soil conditioner:The sensitivity of soil heavy metal repair increases the difficulty of promotion;Farmland is relatively scattered,economic benefits are low,it is difficult to popularize large-scale demonstration;The scale of governance demonstration is small and the pilot is small;The technology of soil conditioner repair is not mature;The promotion system is not perfect and relevant management policies are not perfect;Farmers have low cultural quality and insufficient ideological understanding.The corresponding countermeasures are put forward according to the problems:Explore the establishment of farmland ecological compensation mechanism,increase government support;Accelerating agricultural transformation and land integration;Strengthening construction of comprehensive demonstration areas for heavy metal pollution control in farmland;Intensify scientific research and accelerate technical maturation;Improve the management system and explore the mode of industrialization restoration.Organize scientific and technological training to improve farmers' cultural quality.