ABSTRACT
Water content at field capacity, or simply field capacity, provides an operational concept for managing soil-water in the root zone. Following thorough wetting of deep, well-drained soils, excess water is re-distributed, and field capacity is reached when the downward drainage flux is materially ceased in the profile.[1-5] Veihmeyer and Hendrickson[1,6] related field capacity to soil-water content held at certain negative pressure or suction, implying that perhaps the field capacity is an intrinsic property of soils. Modern theory of soil-water movement and precise measurement have shown, however, that field capacity is not a constant or an intrinsic property, but rather a transient value that is impacted by initial conditions in soil, depth to water table, and soil profile layering.[7-10]
Nonetheless, field capacity remains a useful operational concept in deep, well-drained soils where downward drainage flux may not cease completely, but becomes negligibly small so that processes of evaporation and root water uptake dominate the depletion of root zone soil-water. Determining field capacity is important in soil-water management like scheduling of irrigation because the water content between field capacity and wilting point becomes available for root water uptake by crops.
