Root processes aeration

Vegetated soils have higher CO2 contents, due to root respiration, than bare soils, and the presence of decomposable organic matter increases O2 uptake and hence CO2 production (Table 14-111). The very process of preparing soils for cultivation increases their aeration and rates of both gaseous exchange and organic matter mineralisation. 

The roots of most plants require abundant oxygen for their metabolic processes and are not likely to enter a near-anaerobic environment. In oxygen-deficient soils plants do not grow normally, and any root extension is likely to be limited to cracks or open spaces where air and moisture are present. The problem here, like most of those involved in growth on exposed subsoils, is limited to soils of high clay content. In more open soils poor aeration could occur only in poorly-drained soils. 

Methane oxidation cannot occur in the absence of oxygen therefore, in wetland soils the process is only important in the surface oxic-anoxic boundary or within the plant root rhizosphere. However, aerated soil regions or oxic layers have been demonstrated to consume as much as... 

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