Effects of Red-mud on Rice Growth and Cadmium Uptake in Cadmium Polluted Soil
A field plot experiment was conducted to study the effect of different amount of red mud application on the growth office and Cd uptake by rice in acidic Cd polluted soil(Alluvial Loamy Paddy Soil).The results showed that rice reached the highest yield as application of red mud up to 4 948 kg·hm-2.The main reason of yield promotion by red mud was that red mud is favor to form the rice effective ear.Meanwhile,red mud application increased the soil pH significantly and decreased the soil available Cd content and rice Cd accumulation.Compared with the control of no red mud application,rice yield was increased by 12.4%(P＜0.05),root Cd content was decreased by 22.00(P＜0.05),and the brown rice Cd content(0.14 mg·kg-1)was decreased by 40.8%(P＜0.01)after red mud application up to 3 000 kg·hm-2;Further when red mud reached 9 000 kg·hm-2,the soil pH was increased by 12.0%(P＜0.01),soil available Cd eontem was declined by 24.9% (P＜0.05),and the Cd content of root,straw and brown rice were decreased by 55.7%(P＜0.01),54.5%(P＜0.01)and 69.9%(P＜0.01)respectively.It could be concluded that it was feasible for remediation of acidic soil moderately or slightly contaminated by Cd using red mud due to its improvement of soil pH and decrease of soil Cd activity.Specially,the secondary pollution of red mud could be avoided due to its very low heavy metal content.But it was necessary to study application parameters systematically for the widespread application of red mud in acidic paddy soil polluted by Cd.Moreover,the relevant agricultural machinery and incentive mechanism should be adopted to encourage the farmers spontaneously.
red mudacidic paddy soil polluted by Cdsoil available CdCd content in brown rice
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