Soil-crack characteristics — estimation methods applied to heavy soils in the NOPEX area

Abstract

The methods of estimation of soil-crack characteristics and the possible influence of soil cracks on the infiltration are described in this article. The most important properties of soil cracks, namely volume of cracks, internal crack surface and soil-crack depth were estimated using easily measured soil characteristics: the specific length of cracks on a soil surface,crack porosity on a soil surface, soil water-content profiles and laboratory estimated relationships between crack porosity and mass soil-water content. Presented methods of soil-crack characteristics estimation were applied on two heavy soils in the NOPEX area, near Uppsala, Sweden. A total volume of soil cracks per unit surface area estimated under current conditions in the field was 27mm of water (Lővsta, CFE 1 , soil covered by rye canopy) and 6.2mm water layer in Marsta, CFE 2, under spring barley canopy. Internal crack surface area was found up to 2.7 times higher than topographic soil surface area (Lővsta) and 13 times higher in the Marsta site under given conditions. Results obtained illustrate possible importance of crack formation on soil-water regime. Characteristics of soil cracks mentioned are a part of input data of mathematical models of infiltration into soil with cracks.