Spatial variability of soil hydraulic properties at field scale

Emil Dimitrov, Milena Kercheva

Abstract: Hydraulic pedotransfer functions are tested and applied for estimation the spatial variability and mapping of soil water retention characteristics of soils with heterogeneous texture were estimated and mapped at field scale in the vicinity of Sofia. The monitoring grid consisted of 41 points regularly distribured on area of 1 km2 comprised mainly of Deluvial meadow soil and partly of Cinnamonic meadow and Cinnamonic forest vertisol-like soils. The distances between the points of the grid were 100-200 m and covered cultivated and temporary non-cultivated area. The total organic carbon content ranged from 0.7 to 2.5% in 0-20 cm soil layer and was in average 1.3% in top 0-10 cm layer and 1.0% in 10-20 cm layer. The maximum values were associated with the areas not cultivated for more than 40 years. The data for soil moisture retention at suctions -33 kPa (W33) and -1500 kPa (W1500), soil textural fractions and organic carbon content measured in the horizons of 4 soil profiles were used to test pedotransfer functions. The best prediction for field capacity (W33) was obtained using clay content (particles <0.002 mm, %) and total organic carbon content as predictors, while the wilting point (W1500) depended only on the clay content. The estimated values of field capacity, wilting point and available water capacity of 0-20 cm soil layer in each grid point were used for preparing field maps for these soil hydraulic properties.

Keywords: available water capacity; field capacity; field scale maps; hydraulic pedotransfer functions; organic carbon; soil texture fractions; wilting point

Date published: 2021-06-30