Measurement of aeration, respiration rate and oxygen diffusion in soil during the growth of cotton in a rhizotron

Abstract

Gaseous diffusion experiments were conducted in soil below cotton plants in a rhizotron throughout a growing season. Buried oxygen transducers permitted the estimation of transient-state oxygen diffusion coefficients after soil sterilization with methyl bromide at the end of the season. This provided a relationship between soil air-filled porosity and oxygen diffusion coefficient which was applied in calculations of soil respiratory activity at steady state earlier in the season. These values varied with root density throughout the season. Transient-state values for respiratory activity were different from steady-state values at similar times, even when allowance was made for continual loss of water by transpiration during the transient state. Possible reasons for such differences are discussed, and the utility of the technique for field studies is outlined.