In dry areas or during the dry period in the middle zone of our country applies artificial watering of crops. However, sometimes the question arises: how can quickly determine at what depth infiltrated water? And in this case will assist a sound generator. It is known that, depending on soil moisture changes its conductivity. Hence, the change in the electrical resistance of the layer of soil on different depths can determine its humidity. To do this, in the output circuit generator or a chain bases of transistors connected two sensors (see Fig. 1).
Fig. 1. The soil-moisture meters - satellite archaeologist
Sensors-probes represent rods-tubes of insulating material with a diameter of 15-20 mm. On the surface of the rods along their axes rigidly secured electrodes. These electrodes are made in the form of thin brass or copper the tubes and are secured to the rods at some distance from each other. Each the electrode probe with the help of one of the wires of the multiwire cable is connected to switch P1 of the measuring sound generator. The switch allows connect the generator to the one of the pairs of electrodes. Thus each pair of electrodes, consequently, each position 1-6 switch P1 corresponds a certain depth of soil layer.
Inserting sensors into the ground, as shown in the figure, the switch electrodes and to change the volume or frequency of sound that's heard in the head phones, make conclusion about the depth of irrigation and soil moisture. For ease of determining the depth the location of the electrode in the soil, these values of depth can be marked on a scale switch P1.
Value (sensor) probes selected almost. Also practically, in depending on the specifics of the measurement, selects the number of electrodes, determined by their length and matched the distance between the probes. Of course, our the device gives the ability to make approximate conclusions, however, after the acquisition of practical skills definition will be more accurate.
The design of the device can be somewhat more difficult, replacing the headphones sensitive electric bridge with a galvanometer. This more accurate the device can be used for construction and survey purposes and during archaeological excavations. It will help to detect heterogeneity or large the objects in the surface layer of the soil, as such items will be to change the resistance of the soil at the appropriate depth.
Author: Verhale Yu.