Full explanation
Field capacity (FC) = soil water potential at −33 kPa (−1/3 bar). Per DSTU 4730:2007 it is determined in the lab by the pressure-plate Richards method, or in-field by fully saturating a 1 m² area with 1 m³ of water and covering it with plastic for 72 h. Typical Ukrainian soils: chernozems 28–34%, grey forest 24–30%, sod-podzolic 18–25%, solonchaks 25–32%. From FC to wilting point (−1500 kPa) is plant-available water. Plant-available water (PAW) for chernozems = FC − WP = 18–22% volume = 180–220 mm in a 1 m profile. Farmers use FC for: (1) irrigation scheduling; (2) drought modelling via AquaCrop/CROPWAT FAO; (3) hybrid selection for regional water availability. On-farm measurement: tensiometer (−5 to −85 kPa) or gypsum blocks.