Remediation Effects of Water Management and Lime Application on Seasonally-Fallowed Cd-Contaminated Paddy Fields
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 significantly 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 flooded 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 significantly 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 1000 kg/hm2 or kg/hmss2 could improve soil pH value by 0.2382 or 0.2465 units respectively, and reduce the effective Cd content to 0.0075 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 5120 kg/hm2, and the minimum limit of the Cd content in rice was 0.1242 mg/kg; and the lime theoretic application rate for the highest yield of late rice in the submerged water fallow was 4636 kg/hm2, the minimum theoretic Cd content in rice is 0.1007 mg/kg, and it could reduce the Cd content in rice under the condition of submerged fallow and decrease the dosage of lime.
RiceWater managementLime applicationSeasonal fallowCadmium pollutionHeavy metal
NETL
NSTL
万方数据
维普
