FIELD CAPACITY OF WATER IN SOILS: CONCEPTS, MEASUREMENT, AND APPROXIMATION

Authors: NACHABE, M - UNIVERSITY OF S. FLORIDA; Ahuja, Lajpat; ROKICKI, RENEE - UNIVERSITY OF S. FLORIDA

Submitted to: Encyclopedia of Water Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/1/2002
Publication Date: 7/28/2003
Citation: Nachabe, M.H., Ahuja, L.R., Rokicki, R. 2004. Field capacity of water in soils: concepts, measurement, and approximation. Encyclopedia of Water Science. Stewart, B.A. and Howell, T.A. (eds.) Marcel-Dekker. Book chapter. pp. 915-918. 2003.

Interpretive Summary: We propose to use field capacity as an operational concept for root zone water management, and avoid treating it as an intrinsic soil property. Field capacity is reached when downward drainage flux is negligibly small (while recognizing that drainage may not cease completely) so that evaporation and transpiration are more significant in depleting soil- water of the root zone. Depending on type of application, a negligibly small drainage flux between 0.01 and 1 mm/day can be hindered by a clay pan, whereas in a soil with shallow depth to water table, an equilibrium soil-water profile is usually achieved when drainage ceases to be significant.

Technical Abstract: We propose to use field capacity as an operational concept for root zone water management, and avoid treating it as an intrinsic soil property. Field capacity is reached when downward drainage flux is negligibly small (while recognizing that drainage may not cease completely) so that evaporation and transpiration are more significant in depleting soil- water of the root zone. Depending on type of application, a negligibly small drainage flux between 0.01 and 1 mm/day can be hindered by a clay pan, whereas in a soil with shallow depth to water table, an equilibrium soil-water profile is usually achieved when drainage ceases to be significant.