Using High‐Resolution Soil Moisture Data to Assess Soil Water Dynamics in the Vadose Zone

Abstract

Infiltration and water flow in soils are highly transient processes, but may be estimated from high frequency measurements of soil water content. The objectives of our study were to assess the impact of vadose zone soil water dynamics from real‐time and near‐continuous soil water content measurements and to assess the interactive effects of tillage, row position, and season on water infiltration, storage, drainage, and crop water uptake. Multisensor capacitance probes were installed at row and interrow positions at four soil depths in plow tillage (PT) and no tillage (NT) corn (Zea mays L.) plots, with volumetric water contents values recorded every 10 min for a 30‐mo period. Three water parameters (cumulative water storage, net water storage, and drainage below 55 cm) were grouped for statistical analysis by rainfall amounts and “seasons” of primary periods of groundwater recharge and evapotranspiration. Crop water uptake amounts during extended dry‐down periods were also quantified. We found more significant differences between tillage and row position treatments for high rainfalls (>17 mm) than for low rainfalls. When significant differences in the three water parameters existed between positions, these were due either to greater values in the row position or smaller values at the traffic interrow position. In general, more water uptake took place under PT than under NT and from row more than interrow or traffic interrow positions. These results show both the value and limitation of near‐continuous real‐time soil water data for quantifying soil water dynamics in varying management and weather conditions.