Prediction of Cadmium Uptake by Rice in Paddy Soils near Closed Mine Area

Won-Il Kim*, Goo-Bok Jung, Jong-Sik Lee, Jin-Ho Kim, and Jeong-Taek Lee Division of Agricultural Environment and Ecology, National Institute of Agricultural Science and Technology, 441-707, Suwon, Korea (wikim@rda.go.kr)

Abstract : Concern has increased over the last 40 years for Cadmium(Cd) contamination of paddy soils and the effects may be having on the food chain through rice which is one of staple food in the northeast and southeast Asia. To develop prediction model for the uptake Cd by rice on the basis of soil physico-chemical properties, 108 soil and rice samples were collected and analyzed at the 7 closed mine area through 2001 to 2002. Soil pH, organic matter content, and clay content were major components of the model as major factors controlling Cd availability in paddy soil and were ranged from 4.2 ~ 7.9, 4.82 ~ 57.20 mg kg-1, and 4.5 ~ 25.9%, respectively. Soil 0.1N HCl extractable and total Cd concentrations for the field studies ranged from 0.04 ~ 14.3, and 0.94 ~ 18.6 mg kg-1, respectively. The 0.1N HCl extractable Cd was negatively correlated with soil pH and clay content whereas positively correlated with soil organic matter content and Cd content in rice. The average 0.1N HCl extractability against total content of Cd in soils was determined by 49.1% after acid digestion. Rice Cd concentrations in the paddy studies ranged from 0.01 ~ 2.13 mg kg-1 FW. Model was developed using multiple regression equation to RiceCd = 0.939 + 0.0616 SoilHCl extractable Cd - 0.0066 OM - 0.0912 pH - 0.0065 Clay (R2=0.182***) considering soil pH, soil organic matter content, clay content and 0.1N HCl extractable Cd content in soil. However, model was more comparatively effective adding total Cd in soil and logarithm in the equation with log RiceCd = -1.600 + 1.11 log Soiltotal Cd - 0.014 OM + 0.180 pH - 0.032 Clay (R2=0.404***).