Measurement and calculation of hydraulic conductivity in horizons of tilled and untilled loess-derived soil,Germany

A new rapid and simple method was employed to determine unsaturated hydraulic conductivity functions within A-, B- and C-horizons of tilled and untilled loess-derived soil. The results obtained by the laboratory method compared well with results obtained by a lysimeter technique. Tillage as well as structural and textural differences affected the conductivity functions, and the differences, in diffusivities proved to be significant. Conductivity at low tensions was drastically reduced within the 20–30 cm layer of tilled soil, which had a low porosity caused by the compressing action of the plough. Also in the non-compressed 10–20 cm layer of tilled soil, conductivity at low tensions was lower than that in the 10–20 and 20–30 cm layer of an adjoining field which was left untilled for the previous 6 years. In a few layers, where the laboratory procedure failed, conductivity functions were obtained by a calculation method based on the soil-moisture characteristic. The data gained by the laboratory procedure were then used for matching the calculated conductivity functions. The new method is recommended for soil physics and tillage research.