Biologia 70/11: 1468—1473, 2015 Section Botany DOI: 10.1515/biolog-2015-0182 Spatial variability of hydrophysical properties of fallow sandy soils Renáta Sándor 1,2, *, Ľubomír Lichner 3 , Tibor Filep 1 , Kitti Balog 1 , Éva Lehoczky 1 & Nándor Fodor 4 1 Institute for Soil Sciences and Agricultural Chemistry, Centre for Agricultural Research, Hungarian Academy of Sciences, Herman Ottó str. 15., H-1022 Budapest, Hungary; e-mail: sandor.renata@agrar.mta.hu 2 Grassland Ecosystem Research Unit, INRA, 5, Chemin de Beaulieu, 63039 Clermont-Ferrand cedex 2, France 3 Institute of Hydrology, Slovak Academy of Sciences, Račianska 75, SK-83102 Bratislava, Slovakia 4 Agricultural Institute, Centre for Agricultural Research, Hungarian Academy of Sciences, Brunszvik str. 2., H-2462 Mar- tonvásár, Hungary Abstract: Spatial heterogeneity of soil hydrophysical properties was estimated in 2 fallow sandy soils at Csólyospálos and ¨ Orbottyán, Hungary. Significant differences in small particle (= silt + clay) content (5.0% vs. 13.7%), organic matter content (1.62% vs. 0.91%), and CaCO3 content (3.1% vs. 5.1%) measured at Csólyospálos and ¨ Orbottyán, respectively, resulted in a higher persistence of water repellency in the Csólyospálos soil. It also resulted in a significantly higher water sorptivity and hydraulic conductivity of the ¨ Orbottyán soil. The spatial heterogeneity of soil hydrophysical properties was significant reaching 3 orders of magnitude differences due to the variances of soil properties. The water repellency cessation time was inversely related to the hydraulic conductivity and water sorptivity at Csólyospálos site. Key words: hydraulic conductivity; mini disc infiltrometer; organic compounds; sorptivity; spatial heterogeneity; water repellency. Introduction Climate change increases the frequency and intensity of extreme events such as dry and heat waves and wild- fires, resulting in rapid changes in soil temperature and soil water content (Goebel et al. 2011; Csorba et al. 2014). These changes can induce soil water repellency, mainly in coarse-textured soils rich in organic com- pounds derived from living or decomposing plants or microorganisms (Doerr et al. 2000; Lichner et al. 2013a, b), and influence soil aggregate stability (Czachor & Lichner 2013; Leelamanie & Karube 2014), sorptivity, hydraulic conductivity (k) of soils(Novák et al. 2009; Lichner et al. 2010, 2012; Czachor et al. 2013). The hy- draulic conductivity is one of the most important hy- draulic properties (Fodor et al. 2011) thereby it has an effect on the surface runoff and infiltration furthermore k is a necessary parameter for crop and hydrological models to describe the water flow movement in soils. The degree of soil water repellency was found to be in- versely related to the soil moisture content (Doerr & Thomas 2000) and pH (Diehl et al. 2010). Soil water repellency, caused by organic compounds derived from living or decomposing plants or microorganisms (Doerr et al. 2000; Hallett 2007; Lichner et al. 2012), is formed by the hydrophobic compounds originated from both the decomposing grass thatch, leaves, stems, remnants and mucilages of grass roots (Bisdom et al. 1993; Dekker et al. 2001; Moradi et al. 2012). This soil hydraulic prop- erty may determine the type of natural vegetation and the amount of yield as well (Fodor et al. 2011; Schwen et al. 2011). The hydraulic properties of the subsurface layer show large variations on regional scale (Kořenková et al. 2015) and even within smaller distance (Hendrayanto et al. 2000). The pedon surface is generally considered to be ‘homogenous’ but it may be heterogeneous due to the variability of soil physical properties such as spatial changes of hydraulic conductivity. The objective of this study was to estimate the spa- tial variability of hydrophysical properties (water sorp- tivity, S w ; hydraulic conductivity, k; water drop pen- etration time, WDPT; and water repellency cessation time, WRCT) of two sandy soils under fallow vegeta- tion within pedon scale. Material and methods The experimental sites were located at the Great Hungarian Plain. The region has a continental climate, with cold win- ters and warm or hot summers. The average annual tem- perature is about 10 ◦ C, in summer ∼31 ◦ C, and in winter ∼–7 ◦ C, with extremes ranging from about 42 ◦ C in summer to –35 ◦ C in winter. Average annual rainfall is about 520– 540 mm (D¨ ovényi 2010). The selected two sites: Csólyospá- * Corresponding author c 2015 Institute of Botany, Slovak Academy of Sciences Brought to you by | University of Toronto-Ocul Authenticated Download Date | 1/30/18 9:46 AM