Principle:

Gravitation lysimeters are used to measure parameters to calculate water and solute balances in soils. Due to the high resolution weighing system the input water fractions are measured with a resolution of 0,01 mm, including dew, rime and the water equivalent of snowfall and small rates of evapotranspiration. In connection with the additional recording of the amounts of percolating water and precipitation it also permits the quantification of water balance of the soil column. The actual evapotranspiration can easily be derived using following equation:  

Eta = P – S ± ΔS

_{ETa actual evaporation (mm)}

_{P amount of precipitation (mm)}

_{S amount of seepage water (mm)}

_{ΔS change of water storage capacity (mm, based on measuring the change of weight of the soil column over time;  1 kg = 1 l/m² = 1mm}

If the water balance is calculated correctly, the solute balance can be simply determined with sufficient accuracy using the following equation:

L = Sc x S

_{L load of the solute (mg/m²)}

_{Sc concentration of the solute in the seepage water (mg)} 

_{S amount of seepage water (l/m2 = mm)}