Oxygen diffusion in soils: Understanding the factors and processes needed for modeling

José Neira1*, Mauricio Ortiz1, Luis Morales2, and Edmundo Acevedo2
Oxygen is an important element for plant growth. Reducing its concentration in the soil affects plant physiological processes such as nutrient and water uptake as well as respiration, the redox potential of soil elements and the activity of microorganisms. The main mechanism of oxygen transport in the soil is by diffusion, a dynamic process greatly influenced by soil physical properties such as texture and structure, conditioning, pore size distribution, tortuosity and connectivity. Organic matter is a modifying agent of the soil’s chemical and physical properties, affecting its structure and the porous matrix, which are determinants of oxygen transport. This study reviews the theory of soil gas diffusion and the effect of soil organic matter on the soil’s physical properties and transport of gases. It also reviews gas diffusion models, particularly those including the effect of soil organic matter.
Keywords: Diffusion, diffusion coefficient, Fick’s laws, organic matter, oxygen transport.
1Centro de Estudios Avanzados en Fruticultura (CEAF), Camino Las Parcelas 882, sector Los Choapinos, Rengo, Chile. *Corresponding author (jneira@ceaf.cl).
2Universidad de Chile, Facultad de Ciencias Agronómicas, Santa Rosa 11315, La Pintana, Santiago, Chile.