Effects of Soil pH, Texture, Moisture, Organic Matter and Cadmium Content on Cadmium Diffusion Coefficient

The supply of cadmium from soil to plant roots mainly depends on the diffusion prooess.This work was conducted to study the effects of some soil properties on cadmium diffusion coefficient (D) in soil. Measurements were made using the Shofield and Graham-Bryce‘s isotopic labelling method.Cadmium diffusion coefficients varied from 10^-7to 10^-9 cms^2-1.Higher values were observed in acid sandy soils and lower values in calcareous clay soils.Liming an acid soil resulted in a substantial decrease of D.Addition of cadmium as nitrate salt generally increased D,while addition of sewage sludge and organic matter resulted in a significant decrease of cadmium diffusion.The rhizospheric activity also induced a moderate reduction in D.The relationships between D(10^-9cms^2-1)on the on hand and soil pH.moisture(Mc,g kg^-1) ,organic matter(OM,g kg^-1),clay(Cy,gkg^-1)and cadmium content(Cd,mgkg^-1) on the other were obtained by the multiple regression:D=182.1-29.91pH 0.210Mc-0.303OM 0.011Cy 1.64Cd(R^2=0.859,n=22).

Effects of Soil pH, Texture, Moisture, Organic Matter and Cadmium Content on Cadmium Diffusion Coefficient

The supply of cadmium from soil to plant roots mainly depends on the difFusion process. This work was conducted to study the effects of some soil properties on cadmium diffusion coefficient (D) in soil. Measurements were made using the Shofield and Graham-Bryce's isotopic labelling method. Cadmium diffusion coeffiaents varied from 10-7 to 10-9 cm2S-1.Higher values were observed in acid sandy soik and lower values in calcareous clay soils. Liming an acid soil resulted ina substantial decrease of D. Addition of cadmium as nitrate salt generally increased D, while addition of sewage sludge and organic matter resulted in a significant decrease of cadmium ditFusion. The rhizospheric activity also indrrxd a moderate reduction in D. The relationships between D (10-9cm2S-1) on the one hand and soil pH, moisture (Mc, g kg-1), organic matter (OM, g kg-1), clay (Cy, g kg-1) and cadmium content (Cd, mg kg-1) on the other were obtained by the multiple regression:D=182.1-29.91pH+0.210Mc-03030M+0.011 Cy+1.64Cd (R2=0.859, n=22).