SOIL MOISTURE SAMPLING IN THE UNSATURATED ZONE OF THE SOIL

Different analysis of soil samples out of the unsaturated zone of the soil will be carried out by soil extracts (1:2) after soil sampling. You can ask yourself if the available elements in the soil will be relaised or not, after shaking and filter of this samples.

In the open and in a greenhouse the most cultivated plants are growing for production. Therefore it is necessary that the dressing must be perfect in the unsaturated zone of the soil. Moreover it is important that the availability of water is fine, but by assimilation and transpiration through plants there is an interaction of water and elements in the rootzone (figure 1).

Plants which are grown for production are sensitive to this interactions and therefore it is necessary to check very often each change in the rootzone of the soil by sampling frequently.

At present there is a simple way to collect soil-water samples directly out of the unsaturated zone of the soil. It is possible to take available soil moisture out of the soil if the water content is higher than pF 2.7. The principle is that water is collected on the spot by means of a ceramic cup placed in the soil (figure 2).

By creating a sub atmospheric pressure in the pot, the surrounding soil moisture will penetrate into the pot. Soil moisture will by the sub-pressure in the sampling system move through the porous medium and through the longer pvc-tube into the collecting bottle, which one is turned of very tightly with a rubber cork. When there is sufficient moisture the probe is emptied with the shorter pvc-tube. By opening the pinch on this tube the outside atmospheric will transport the water round the cermaic cup, via the pvc-tube into the bottle, so as to avoid influence on subsequent samples.