Distribution of carbon dioxide and methane in the of irrigated sierozems

The concentrations of CO₂ and methane in soil air have been measured in different horizons of the profile of irrigated sierozemic soils of Uzbekistan. The data obtained on a typical sierozem and a meadowsierozemic soil under wheat and cotton fields during different phases of plant growth show that the maximum concentration of CO₂ in the soil air is observed at the depth of 60–80 cm. This is explained by the maximum content of roots of winter wheat and cotton in this layer; this is also the layer with the maximum content of microorganisms producing CO₂ in the course of microbial respiration. In the regularly irrigated sierozemic soils, anaerobic conditions are formed after irrigation. They favor the development of anaerobic microorganisms producing methane in relatively small amounts. The distribution of methane in the soil air along the soil profile is more even than that of CO₂ (the variation coefficients are 0.14 for methane and 0.46 for CO₂).