Fire impact on soil-water repellency and functioning of semi-arid croplands and rangelands: Implications for prescribed burnings and wildfires Ilan Stavi a, ⁎, Daniel Barkai b , Yaakov M. Knoll b , Hiam Abu Glion b , Itzhak Katra c , Anna Brook d , Eli Zaady b a Dead Sea and Arava Science Center, 88820 Yotvata, Israel b Department of Natural Resources, Agricultural Research Organization, Gilat Research Center, 85280 Negev, Israel c Department of Geography and Environmental Development, Ben-Gurion University of the Negev, 84105 Beer Sheva, Israel d Department of Geography and Environmental Studies, University of Haifa, 3498838 Haifa, Israel abstract article info Article history: Received 27 December 2015 Received in revised form 24 November 2016 Accepted 14 December 2016 Available online 16 December 2016 An unintended fire outbreak during summer 2015 in the semi-arid Israeli Negev resulted in the burning of exten- sive croplands and rangelands. The rangelands have been managed over the long term for occasional grazing, while the croplands have been utilized for rainfed wheat cropping. Yet, during the studied year, the croplands were left fallow, allowing the growth of herbaceous vegetation, which was harvested and baled for hay before the fire outbreak. The study objectives were to investigate the impacts of fire, land-use, and soil depth on water-repellency and on the status and dynamics of some of the most important organic and mineral soil re- sources. Additionally, we aimed to assess the severity of this fire outbreak. The soil-water repellency was studied by measuring the soil's water drop penetration time (WDPT) and critical surface tension (CST). A significant effect of fire on soil hydrophobicity was recorded, with a slight increase in mean WDPT and a slight decrease in mean CST in the burnt sites than in the non-burnt sites. Yet, soil hydrophobicity in the burnt lands was rather moderate and remained within the water repellency's lowest class. A significant effect of land-use on the means of WDPT and CST was also recorded, being eleven-fold greater and 7% smaller, respectively, in the rangelands than in the croplands. This is consistent with the almost eightfold greater mean above-ground biomass recorded in the non-burnt rangelands than in the non-burnt post-harvest croplands, revealing the positive relations between available fuel load and soil-water repellency. The effect of soil depth was significant for CST but not for WDPT. Overall, the gathered data suggest that fire severity was low to moderate. Fire was also found to significantly af- fect the b 250 μm particle size fraction of the unconsolidated material cover, its mass being twofold to threefold greater in the non-burnt than in the burnt sites. Yet, soil organic carbon and ammonium-N were also studied, and generally showed higher values for the burnt lands. Overall, this study shows that the low- to moderate-fire se- verity only slightly increased the soil water repellency, and at the same time, increased on-site availability of some important soil resources. Nevertheless, it is acknowledged that such fires could impose risks to off-site air and water source quality. This study has implications for the assessment of geo-ecosystem functioning, as well as for the status and dynamics of soil resources following prescribed burnings or wildfires. © 2016 Elsevier B.V. All rights reserved. Keywords: Environmental pollution Mixed farming systems Nutrient availability Soil quality 1. Introduction Controlled burnings of farmland crop residue or rangeland above- ground biomass have been prevalent as a common management prac- tice in extensive areas around the world (Brooks et al., 2006). The objectives of prescribed burnings are varied, ranging between the con- trol of weeds (Koski et al., 2011) and pests in croplands (DeFrancesco and Murray, 2011), the control of woody vegetation and other invasive plant species in grasslands and chaparral rangelands (Veach et al., 2014), and as means to control wildfire in shrublands and tree planta- tions (Shakesby et al., 2015). However, while possibly fulfilling these aims, similar to wildfires, burning management practices can have some detrimental impacts on soils, These include the uneven wetting patterns of the soil profile, the development of preferential flow, the decreased availability of water for vegetation, and the increased susceptibility to overland flow generation and soil erosion (Doerr et al., 2000; Bachmann et al., 2002). Geomorphology 280 (2017) 67–75 ⁎ Corresponding author. E-mail addresses: istavi@adssc.org, istavi@yahoo.com (I. Stavi), vcbarkai@volcani.agri.gov.il (D. Barkai), yaakov@volcani.agri.gov.il (Y.M. Knoll), hiam1987@gmail.com (H.A. Glion), katra@bgu.ac.il (I. Katra), abrook@geo.haifa.ac.il (A. Brook), zaadye@volcani.agri.gov.il (E. Zaady). http://dx.doi.org/10.1016/j.geomorph.2016.12.015 0169-555X/© 2016 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Geomorphology journal homepage: www.elsevier.com/locate/geomorph