Soil volumetric water content

Soil volumetric water content has a great impact to the biological and chemical processes in soil. During the average day, soil volumetric water content varies between 25 and 30 percent although it can increase for 35 percent after the rain. Soil volumetric water content has not a specific annual or diurnal cycle, but soil volumetric water content increase after rain when soil pores are mainly or partly filled with water. Soil volumetric water content also regulates evapotranspiration of plants.

Volumetric water content regulates relative conductance of vaporized elements and this affects to the release of these volatile organic compounds since stomata conductance decrease in low volumetric water content. When soil volumetric water content is really high or low, it will cause physiological stress which increases the VOC synthesis of plants.

Soil volumetric water content impacts to the VOC emissions which are released from the soil since microbial activity depends on soil volumetric water content although temperature is the main factor which regulates microbial activity in soil. Increased volumetric water content effects diffusivity of VOC in soil since diffusion coefficient is much lower in water than in air. Root activity also depends on volumetric water content and roots will release VOCs. Soil volumetric water content also regulates activity of surface vegetation which is the major source of VOC from the forest floor.