Diffusion of Zinc in Soil: I. The Influence of Soil Moisture

Abstract

Abstract Effective Zn diffusion coefficients, D e (Zn) , were determined at several soil moistures on six soils by allowing 65 Zn diffuse from the soil into cation exchange resin paper placed on the surface of the soil. At 13% volumetric moisture D e (Zn) values ranged from 10 ‐11 to 10 ‐8 cm 2 /sec with the range narrowing as the soils approached moisture saturation. In five of six soils, the effect of increasing moisture level on D e (Zn) could be explained by its effects on tortuosity and on solution Zn concentration. When solution Zn remained constant as moisture level increased, the relation between D e (Zn) and volumetric moisture was hyperbolic. When solution Zn level dropped as moisture increased D e (Zn) changed very little. In one soil where variation in D e (Zn) with moisture level was not explained by these two factors, a third unknown factor apparently influenced D e (Zn) .