ABSTRACT
The vadose zone is located between the land surface and the water table within which the soil moisture content is below saturation (except in the capillary fringe) and the water pressure is less than atmospheric. In this zone, the soil pore space typically contains air and other gases (e.g., O2, CO2) that are central to the biogeochemistry of the soil-plant-atmosphere system. The dynamics of water and nutrients in this zone impact groundwater quality and quantity through intricate interconnections between physical, biological, and chemical processes attributed to the presence of vegetation, soil microorganism, and their interaction with local climate and above-ground micrometeorology.
