What Can We Learn From the Water Retention Characteristic of a Soil Regarding Its Hydrological and Agricultural Functions? Review and Analysis of Actual Knowledge

The soil properties of the upper soil layer determine the partitioning between infiltration, runoff, and evaporation, key processes related to soil agricultural and hydrological functioning. It is therefore important to have some information on these soil functions based on available and easy-to-measure properties. This study presents what we can learn a-priori from the soil water retention characteristic (WRC) on some important hydrological and agricultural functions. Based on a mathematical expression of the soil WRC, it is possible to estimate: the characteristic length, L-C, related to the disruption of hydraulic continuity of the water liquid phase in the soil; the saturated hydraulic conductivity K-s; the unsaturated hydraulic conductivity function of water and air, K(theta(w)) and K(theta(a)); the saturation degree S-eFC at field capacity and how long it will take to reach that state; the available water content in the soil, AWC; the capillary head at the wetting front, psi(f); the infiltration capacity curve based on the Green and Ampt model, q(cap)(t); the time to ponding, t(p), for any prescribed wetting rate; the cumulative water loss during stage-1 evaporation; the duration of stage-1 evaporation. All these a-priori estimates are valuable and sometimes necessary for efficient design and planning in agricultural and hydrological applications. The values of these estimates depend upon the specific mathematical expression chosen to represent the WRC.

Automated summary

The properties of the upper soil layer play a crucial role in determining infiltration, runoff, and evaporation processes, essential for soil agricultural and hydrological functioning. Understanding important hydrological and agricultural functions based on soil water retention characteristics can provide valuable insights for efficient design and planning in agricultural and hydrological applications.