Labeled Oxygen: Increased Diffusion Rate through Soil Containing Growing Corn Roots

Abstract

The diffusion of oxygen labeled with oxygen-18 through cores of wet soil increased significantly when roots of growing corn seedlings penetrated the cores. The increase was small or absent when roots grew through a layer of soft wax or a layer of water-saturated 0.5-mm glass beads, indicating that the diffusion increase was a joint effect of the roots and airfilled pores in the soil. A possible mechanism is suggested.