Field screening experiments of soil conditioners for typical heavy metal-polluted farmland in Pearl River Delta
To investigate the effects of different soil conditioners on the heavy metal content of soil and rice,screen suitable remediation methods for contaminated farmland,and realize the precise selection of conditioners for safe production,the effects of six commercially available soil conditioners on soil pH,heavy metal content in soil and rice,effective-state Cd content of soil,and rice yield were analyzed under four different early-maturing and late-maturing rice dosage conditions.The results showed that all of the conditioners increased soil pH,and this pH enhancement effect was in the order Jinkuizi>Yuetian>nutrient blockers>Tianxiang>iron-modified biochar>iron-modified woody peat,with the increase ranging from 3.2%to 24.3%.None of the conditioners additionally increased the total amount of each heavy metal in soil samples,and all of them reduced the effective-state Cd content of soil after application,and the order of effective-state Cd reduction was as follows:Yuetian(3,2,1,4)>iron-modified biochar(3)>Tianxiang(2,4,3)>nutrient blockers(1,3)>Jinkuizi(1),with a reduction of 25.0%-58.3%.All the six conditioners reduced the Cd content in the early-maturing rice,and the Cd reduction effect was in the order Tianxiang(2)>Tianxiang(1)>Tianxiang(3)>iron-modified woody peat(1)>iron-modified woody peat(2)>Tianxiang(4)>iron-modified biochar(4)>Yuetian(1),with a reduction range of 47.8%-67.5%,and the Cd content in the reduced rice was in accord with the relevant standards.There were no significant effects on rice yields after the application of the six soil conditioners,and none of the experimental groups with reduced yields decreased by<90%that of the control group,which satisfied the relevant requirements.For typical heavy metal contaminated farmland in the Pearl River Delta,it is recommended that treatment be carried out according to the method of Tianxiang(2),i.e.,applying 2 250 kg of Tianxiang conditioner per hectare during early planting and 2 250 kg of Tianxiang conditioner per hectare during late planting,which can significantly elevate the pH of paddy field soils,reduce the effective Cd content of such soils,and reduce the Cd content of paddy rice without affecting yield.
万方数据
维普
