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• Irrigated pasture had greater SWRP than dryland pasture and irrigated crop. • Soils with SOC < 2% tended to be wettable and soils with SOC > 4% repellent. • SWRP curve described by a Gaussian model with three physically meaningful parameters. • Model parameters and SWRPC could be predicted by SOC. Soil water repellency (SWR) affects hydrological processes such as water infiltration, preferential flow, run-off, and evapotranspiration. Understanding the relationship between SWR and volumetric soil water content (θ) is critical for predicting hydrological processes in hydrophobic soils. In this study, water droplet penetration time (WDPT) was used to investigate the SWR persistence (SWRP) in three soil types with contrasting drainage levels, namely a well-drained Lismore (LIS) stony silt loam, a moderately well-drained Templeton (TEM) silt loam, and a poorly drained Waterton/Temuka (WAT) clay loam under three long-term (>20 years) land uses (irrigated pasture [IP], dryland pasture [DP], and irrigated crop [IC]) in Canterbury, New Zealand. The three soils belong to different soil orders (i.e., Brown, Pallic, and Gley, respectively) in the New Zealand soil classification. Within each land use, 9, 12, and 9 sites were sampled in the LIS, TEM, and WAT soils respectively. There was strong evidence of SWR in all three soil types under three land uses. The maximum SWRP (WDPT max), ranging from 6 to 1470 s with the median value of 56 s, differed with land use by following descending order of IP > DP > IC. The effects of land use on SWRP differed with soil type. Compared with other two soils, LIS soil had higher differences in WDPT max between IP and DP, but lower differences in WDPT max between DP and IC. Most of the SWRP parameters were significantly correlated with soil organic carbon (SOC) content. In soils with higher SOC content, SWR usually developed under drier conditions and declined as soils were maintained under wetter conditions. This study suggests that the WDPT max appears at soil water contents of 0.17 to 0.19 cm3 cm−3 (equivalent to 0.15 to 0.16 g g−1). Soil water repellency persistence was positively related to SOC content. Soils with SOC content < 2% tended to be wettable, while soils with SOC content > 4% tended to be water-repellent. A Gaussian model with three physically meaningful parameters was developed to successfully fit the SWRP curve (SWRPC, LnWDPT as a function of θ). Our study also showed the possibility to predict the model parameters and SWRPC using SOC content. The model needs to be tested across other soil types, land uses, and climates before it can be widely applied to predict the SWR occurrence from SOC data. Future work should also focus on the impacts of SOC composition on SWRP parameters and other hydrological properties for predicting soil water processes in water-repellent soils. [ABSTRACT FROM AUTHOR]

• Dryland pasture (DP) had >50% higher AWC than irrigated pasture (IP) and cropping (IC). • DP had highest hydraulic conductivity (K) with no land use and soil type interactions. • Bulk density, SOC and clay explained half variations in AWC but limited variations in K. • Macroporosity (>30 μm) may contribute more to AWC than to K. • SOC mainly contributed to the increase in AWC at the dry end (−40 to −1500 kPa). Soil hydraulic properties (SHP) control water movement and storage and thus affect a wide range of biogeochemical processes and ecosystem services. The objectives of this study were to identify the interactions between long-term land use and soil type on SHP (e.g., available water content [AWC], hydraulic conductivity [K]), and the effects of soil organic carbon (SOC) content on these properties. Soil water release curves and (near) saturated hydraulic conductivity at three soil depths (0–7.5, 7.5–15, and 15–30 cm) were measured under three long-term (>20 years) land uses (irrigated pasture [IP], dryland pasture [DP], and irrigated cropping [IC]) in Canterbury, New Zealand. For each land use, three soil types with contrasting drainage characteristics were selected: well-drained Lismore (LIS) stony silt loam, moderately well-drained Templeton (TEM) silt loam, and poorly-drained Waterton/Temuka (WAT) clay loam. Compared to DP, the IP and IC soils had lower AWC and K. Significant interactions between land use and soil type were found for AWC but not for K. Bulk density, SOC, and clay content could explain half the variation in AWC but had limited influence on K. More variance in AWC (6–13%) and K (5–27%) could be explained by including categorical variables (i.e., land use, soil type, and soil depth) and their interactions with continuous variables, indicating the potential benefit of including these categorical variables when developing pedotransfer functions for AWC and K. This study suggests that many macropores (>30 μm) were poorly connected and contributed more to water storage than to conducting water. The commonly used soil matric potential of −10 kPa was suitable for defining field capacity in DP and IC soils but a lower matric potential (−33 kPa) was more appropriate for IP soil affected by livestock treading during grazing. Soil organic carbon mainly increased AWC by affecting water retention at soil matric potentials of between −40 and −1500 kPa (equivalent to pore size 0.2–7.5 μm). Therefore, soil carbon sequestration may be important to alleviating water stress in dry environments. Our study also suggests that the effects of land use and its interaction with soil type, soil matric potential at field capacity, and soil organic carbon on SHP need to be considered during soil parameterization of hydrological models. [ABSTRACT FROM AUTHOR]