Predicting field capacity in undisturbed stony soils

An increasing number of studies around the world are showing that a long-held assumption rock fragments (RFs) inert with respect to water retention is incorrect. Yet very few pedotransfer functions (PtFs) account for held by RFs or effect have on fine earth. The PtFs incorporate content (WC) relied upon measurement methods may not be representative field conditions. This indicates gap in research regarding characterisation holding behaviour stony soils situ using soil volumes adequately represent soil. We address this developing predict capacity WC storage measurements from 52 pits excavated into Canterbury Plains, New Zealand. These comprise sediment derived Mesozoic hard sandstone. at each site were watered saturation, and then after two days drainage (a proxy capacity), 30 × cm pit was 10 increments depth 60 cm. Matric potential measured increment, calculated samples taken back laboratory. Our results showed it possible accurately only explanatory variables could easily estimated minimalistic survey. existing PtF calibrated NZ (logit PtF), which constructed had no FC other than reducing volume earth, performed worse our models. By modifying logit PtF, we conclude its poorer performance stems inability deviations 1) matric assumes (−10 kPa), 2) RFs, 3) characteristics demonstrate even low porosity study can significantly affect model performance, but including (depth volumetric proportion RFs) routinely most sampling projects, improve prediction accuracy established