Grain size analysis is carried out in our laboratory using both classical and modern, semi-automated methods. The classic methods according to DIN ISO 11277 are (wet) sieving and slurry grain analysis. The latter is carried out by us as a pipette method according to Köhn. As a semi-automated method, we use the integral suspension pressure method (ISP), which our working group developed in cooperation with the company Meter AG from Munich. The method is also based on the sedimentation of particles in aqueous suspension in the earth's gravitational field. The grain sum curve is determined by measuring the suspension pressure and an inverse simulation. The PARIO or PARIO-PLUS measuring device is used in the laboratory. The relevant publications on PARIO or ISP can be found on this website. Prices on request.
The saturated hydraulic conductivity, also called Ks- or Kf-value or water permeability coefficient, is measured in our laboratory with the measuring device KSAT of the company Meter Group. The measurement is carried out on packed or undisturbed soil samples taken in the field with a volume of 250 ml using the falling overpressure method. The method conforms to DIN 18130. The measurement of smaller samples or cylinders is also possible on request. Prices on request.
The relationship between the water content of a soil and the matrix potential of the soil water is the retention curve. It is probably the most important soil physical property for plant growth. In our laboratory we determine the retention curve with the following methods: negative pressure method (matrix potential -300 to 0 hPa), positive pressure method (-15000 to -1000 hPa) and dew point method (less than -10000 hPa, measuring device WP4C). These three methods are static methods. Ecologically relevant quantities such as porosity, saturation water content, water content at sampling, field capacity, air capacity and wilting point can be derived from the measurement of the retention curve. Prices on request.
The retention curve of a soil can also be determined using dynamic or transient methods. In practice, the evaporation method according to Schindler has proven itself due to its accuracy and robustness. In addition to the retention curve, it can also be used to determine the unsaturated hydraulic conductivity of the soil. In our laboratory, the HYPROP measuring device from the Meter Group is used for this purpose. The evaluation software was essentially co-developed by our working group. This is documented in our publications. The results of the evaporation method can be usefully supplemented by results of other measuring methods in order to extend the range of values. The measurement of the saturated hydraulic conductivity (KSAT) supplements the hydraulic conductivity curve towards the wet, the measurement of points of the retention curve in the hygroscopic range with the dew point method (WP4C) extends the retention curve into the dry range. The measurements can be performed on packed samples as well as on samples minimally disturbed in the field. Prices on request.
The thermal conductivity of soil depends on the texture, mineralogical composition, organic matter content and soil water content. In our laboratory we carry out measurements of the thermal conductivity of the soil at different water contents. For the measurement, we use a thermal needle system that injects a heat pulse into the soil and precisely measures the decay of the temperature. We use the TEMPOS device from Meter AG for the measurement and combine it with an evaporation method. Prices on request.
We carry out numerical simulations of water, heat and mass transport in variably saturated porous media using the Hydrus-1D and Hydrus-2D3D program packages. There is the possibility of combination with the above described measurement methods of soil physical parameters. Prices on request.