Flux-Based Estimation of Field Capacity

Abstract

Field capacity has been defined as the water content at which the drainage flux from a soil ceases, or becomes negligible. Field capacity is most commonly estimated as the water content at a pressure head of 1/3 bar, which ignores its flux-based nature. A number of authors have proposed estimating field capacity as the water content at a given (negligible) flux, assuming unit gradient conditions. This flux-based method of estimating field capacity is discussed and the differences between this method and the more common pressure-based method are illustrated. The drainage flux considered to be negligible will depend on the particular application; values between 10