Suat Irmak

Robust assessment of crop water availability requires effective integration of soil moisture data within the range of field capacity ( θ FC ) to permanent wilting point ( θ PWP ). Emerging needs for spatiotemporally dynamic θ FC and θ PWP are difficult to achieve with lab determinations. Therefore, we used long‐term data from 182 sites across the United States to evaluate whether soil moisture extremes defined by 95th and 5th percentiles represent θ FC and θ PWP , respectively. Soil moisture extremes and lab‐measured θ FC and θ PWP were well correlated ( R 2 = 0.71−0.92), however, both 95th and 5th percentiles overestimated θ FC and θ PWP at most depths (RMSE = 6%–16% vwc). Percentiles of soil moisture distribution that corresponded to lab‐determined θ FC and θ PWP varied widely and were a function of precipitation received at the site and site‐ and soil‐depth specific clay content. These findings imply that while θ FC and θ PWP may not be broadly represented by soil moisture extremes (95th and 5th percentiles), there may be potential to statistically infer the positioning of θ FC and θ PWP within long‐term soil moisture distributions using biophysical determinants such as aridity and soil characteristics.