In the light of the national policy of fallow, this study was conducted to determine how the different water management and lime application would affect soil physical and chemical properties, rice yield and cadmium ...In the light of the national policy of fallow, this study was conducted to determine how the different water management and lime application would affect soil physical and chemical properties, rice yield and cadmium （Cd） content of rice in fallow season. The results showed that, compared with the arid fallow, the waterlogging fallow decreased the soil pH value whereas signifcantly increased the soil organic matter content and the cation exchange quantity, and reduced the soil effective cadmium content and the rice cadmium content whereas could increase the rice yield to a certain extent. In the fooded fallow or the dry fallow, the application of lime mainly depended on the alkali conditioning of lime and the antagonistic effect of Ca2＋, which could signifcantly reduce the cadmium content of rice, and its effect would increase linearly with the increase of lime dosage, whereas had no significant effect on soil organic matter content and cation exchange quantity. In order to establish a linear equation of lime dosage and related indexes under the condition of waterlogging fallow or dry fallow, calculations showed that each application of lime at 1 000 kg/hm2 or kg/hmss2 could improve soil pH value by 0.238 2 or 0.246 5units respectively, and reduce the effective Cd content to 0.007 5 mg/kg both in the arid fallow and the waterlogging fallow conditions. The lime theoretic application rate for the lowest Cd content of late rice in the arid fallow was 5 120 kg/hm2, and the minimum limit of the Cd content in rice was 0.124 2 mg/kg; and the lime theoretic application rate for the highest yield of late rice in the submerged water fallow was 4 636 kg/hm2, the minimum theoretic Cd content in rice is 0.100 7 mg/kg, and it could reduce the Cd content in rice under the condition of submerged fallow and decrease the dosage of lime.展开更多
A field experiment was conducted to evaluate the remediation effects of 14 soil conditioners for Cd-polluted paddy fields contrasted with conventional fertilization and liming.The results showed that soil conditioners...A field experiment was conducted to evaluate the remediation effects of 14 soil conditioners for Cd-polluted paddy fields contrasted with conventional fertilization and liming.The results showed that soil conditioners had no significant impact on rice yields.Though the soil conditioners had stable effects on decreasing the Cd content in grains,the effects varied with the category of conditioners.In general,The Cd contents of early rice and late rice were reduced by 22.65%~44.24%and 15.20%~63.03%,respectively.Additionally,the stem and leaves showed the same decreasing tendency.Cluster analysis suggested that soil conditioners can be divided into three categories:the first category increases the soil pH to inhibit the Cd activity and cut down the Cd translocation from soil to stem and leaves,which is most efficient in the reduction of Cd content in rice grains;the other category relies on the antagonism or co-precipitation between Cd and certain elements to inhibit the translocation and redistribution of Cd from rice stems to grains,providing a common effect on Cd reduction;the last category can be seen as a combination of the former two categories from the perspective of its functional mechanism and it has a moderate effect on the reduction of Cd contents in rice grains.展开更多
文摘In the light of the national policy of fallow, this study was conducted to determine how the different water management and lime application would affect soil physical and chemical properties, rice yield and cadmium （Cd） content of rice in fallow season. The results showed that, compared with the arid fallow, the waterlogging fallow decreased the soil pH value whereas signifcantly increased the soil organic matter content and the cation exchange quantity, and reduced the soil effective cadmium content and the rice cadmium content whereas could increase the rice yield to a certain extent. In the fooded fallow or the dry fallow, the application of lime mainly depended on the alkali conditioning of lime and the antagonistic effect of Ca2＋, which could signifcantly reduce the cadmium content of rice, and its effect would increase linearly with the increase of lime dosage, whereas had no significant effect on soil organic matter content and cation exchange quantity. In order to establish a linear equation of lime dosage and related indexes under the condition of waterlogging fallow or dry fallow, calculations showed that each application of lime at 1 000 kg/hm2 or kg/hmss2 could improve soil pH value by 0.238 2 or 0.246 5units respectively, and reduce the effective Cd content to 0.007 5 mg/kg both in the arid fallow and the waterlogging fallow conditions. The lime theoretic application rate for the lowest Cd content of late rice in the arid fallow was 5 120 kg/hm2, and the minimum limit of the Cd content in rice was 0.124 2 mg/kg; and the lime theoretic application rate for the highest yield of late rice in the submerged water fallow was 4 636 kg/hm2, the minimum theoretic Cd content in rice is 0.100 7 mg/kg, and it could reduce the Cd content in rice under the condition of submerged fallow and decrease the dosage of lime.
基金Supported by Specialized Scientific Research in Public Welfare Sector Water Resources Ministry(201501019)Scientific and Technological Innovation Project in Hunan Academy of Agricultural Sciences(2017JC57)+1 种基金Science and Technology Planning Project in Changsha(kq1703010)Post Scientist of Rice Industrial System in China(CARS-01-28)~~
文摘A field experiment was conducted to evaluate the remediation effects of 14 soil conditioners for Cd-polluted paddy fields contrasted with conventional fertilization and liming.The results showed that soil conditioners had no significant impact on rice yields.Though the soil conditioners had stable effects on decreasing the Cd content in grains,the effects varied with the category of conditioners.In general,The Cd contents of early rice and late rice were reduced by 22.65%~44.24%and 15.20%~63.03%,respectively.Additionally,the stem and leaves showed the same decreasing tendency.Cluster analysis suggested that soil conditioners can be divided into three categories:the first category increases the soil pH to inhibit the Cd activity and cut down the Cd translocation from soil to stem and leaves,which is most efficient in the reduction of Cd content in rice grains;the other category relies on the antagonism or co-precipitation between Cd and certain elements to inhibit the translocation and redistribution of Cd from rice stems to grains,providing a common effect on Cd reduction;the last category can be seen as a combination of the former two categories from the perspective of its functional mechanism and it has a moderate effect on the reduction of Cd contents in rice grains.
