Tensiometer (digital) 30cm Blumat

Measuring soil moisture is an extremely important task in crop production, as it is the water in the soil that allows the uptake of nutrients essential for plant life.
There are several methods for measuring soil moisture. The most common of these is the liquid tension method. It is cheap and easy to use, and gives reliable and accurate results.
The water in the soil is influenced by certain associated forces, which include an appropriate water tensiometry. Through the contact between the water-saturated cell and the soil, the low soil moisture pressure present in the soil is transmitted through the clay cell and the water-saturated tube to the meter, from where the pressure level can be read. The only drawback of this measurement method is that it is not mobile, i.e. the device can only be used when stationary.
General construction
Tensiometers consist of 3 main parts. At the bottom is a fine ceramic tip with a porous structure, connected to a transparent Plexiglas tube. At the upper end of the tube is a gauge for measuring negative pressure (vacuum). This instrument can be of the conventional type, or of the un. It may be a conventional, conventional Burdon tube indicator or it may be an electronic instrument with a digital display. The system is filled with water during operation.
Operating principle
When the system is placed in the ground, fully filled with water and sealed, after a short time some of the water is observed to escape from the system through the capillaries of the porous ceramic tip, creating a vacuum in the tube.
The value of the vacuum can be read from a dial gauge on the top of the instrument. The vacuum level is related to the soil moisture content. The drier the soil, the more moisture is drawn out of the tube through the ceramic tip. Thus, the current value of vacuum is representative of the current moisture level in the soil. Of course, the process is bidirectional, i.e. as the soil moisture is reabsorbed, the vacuum in the instrument tube decreases as the water in the soil reabsorbs the water that was previously removed through the ceramic tip.
Usage
Place the ceramic tip at the bottom of the instrument in a pot of water for about 1 hour to ensure that it is completely soaked. Then fill the Plexiglas tube to the top with water and screw the vacuum gauge onto the threaded end of the tube. In this case the gauge will read zero, as the system is at maximum water saturation. This is the initial condition, the instrument is ready for use.
Select the location where you want to install the instrument. Using a thicker piece of iron pipe and a larger hammer, you can easily make a suitable hole for the instrument. The depth of the hole should be chosen so that the ceramic tip is at the height of the root zone. Place the instrument in the hole, sprinkle soil around it and tamp it down thoroughly. After 2-3 hours, an accurate vacuum value can be read, which is representative of the soil moisture content.
As soon as the soil moisture pressure drops, the soil moisture suction intensity rises and this negative pressure is displayed on the meter.
Interpreting the data
The optimum soil water content depends on the water absorption capacity of the soil and is displayed on the meter.
The suction force depends to a large extent on the soil type. Therefore, it is necessary to determine the optimum suction power value for your own soil
determination.
Optimum values:
Between -100 mbar and -300 mbar.
(At -100 mbar, irrigation must be started for sandy soils.
-at -300 mbar, irrigation must be started for clayey soils)

Vacuum values
(mbar)
Planting soil
mbar/PSI
Garden soil,
Average quality soil

Clay granular soil
After transplanting
First 3 months:
After:
10 - 40
0,15 - 0,60
30 - 150
0,45 - 2,3
Saturated to very wet


50 - 120
0,7 - 1,8
150 - 250
2,3 - 3,8
Reasonably wet
40 - 60
0,6 - 0,8
40 - 70
0,6 - 0,9
120 - 190
1,8 - 2,8
250 - 300
3,8 - 4,5
Moderately moist to dry
(irrigation required)
60 - 70
0,8 - 0,9
70 - 100
0,9 - 1,5
200 - 300
3,0 - 4,5
310 - 500
4,6 - 7,7
From initial dry to dry
(irrigation absolutely necessary)
80 - 100
1,2 - 1,5
110 - 150
1,6 - 2,3

Attention!
Optimum values should be determined according to local conditions (local rainfall, climatic conditions, soil type, etc.). When setting the appropriate irrigation, local conditions and circumstances should be taken into account. For example, in the case of bushland cultivation, in addition to the soil type, the fact that the larger surface area means that the soil dries out more quickly should also be taken into account.
Technical data
(using a conventional indicator)
- Plexiglas tube length: 30, 60 and 100 cm
- Plexi tube diameter: 16/11 mm (outer/inner)
- Measuring range: 0 to -600 mbar/hPa
- Dial gauge diameter: 50 mm
Maintenance and storage

Ensure that the fine ceramic tip is kept clean. Protect it from greasy dirt, which clogs the pores and thus inhibits the flow of fluid.
After several years of use, the ceramic tip will react more slowly than usual. This is due to the fouling of the ceramic tip surface. Clean the contaminated ceramic tip with fine sandpaper.
Use a wet cloth to clean other parts of the instrument.
Do not use solvents for cleaning !
Protect the instrument from strong mechanical shocks (dropping, hitting, etc.) as this may damage the instrument.
To remove the instrument from the ground, carefully dig around the instrument and only then lift it out of the ground.
If for any reason the tube should run out of water (air bubbles appear), remove the instrument from the ground, fill it with water and reinstall it as described in the "Use" section. At the same time, check that the seal between the meter and the Plexiglas tube is adequate.
Winter storage - Unscrew the meter head and store it in a frost-free place. The ceramic tip may remain in the ground, water will simply pass through it.