Full explanation
Wilting Point (WP) is determined per DSTU 4730:2007 in the lab with a Richards pressure plate at 1,500 kPa, or by the field method — a sunflower indicator is planted in a pot of soil without further watering and moisture is measured at permanent wilt. Typical Ukrainian values: central chernozems 10–14%, southern steppe 9–12%, sod-podzolic 6–9%, sandy 3–5%. Note: WP is not «dead water» — it's the point where pine/maize/wheat roots cannot overcome matric potential. Crops have different thresholds: maize wilts earlier (~−1,200 kPa), sunflower reaches near WP (−1,400 kPa), sorghum goes even lower (−1,800 kPa, hence better for drought regions). PAW (Plant Available Water) = Field Capacity − WP — the operational water-supply metric across a season. For AquaCrop-scheduled irrigation, watering starts at 40–50% PAW depletion for sensitive crops (maize, soy), 60–70% for tolerant crops (wheat, sorghum).