How Does the Soil PH Meter Work?
The Soil pH meter is a portable soil testing device that lets you know how much pH your soil actually has.
In fact, knowing your soil acidity levels when looking at making adjustments to its pH is vital. This is because an increase of 1 on a soil pH meter translates to 10 times the acidity of the soil in chemistry terms and will directly affect your planting and growing capabilities in your garden.
How does a soil pH meter work?
The pH meter determines the pH value by measuring the voltage to determine the level of hydrogen ions. The more hydrogen ions in the solution, the better it conducts electricity. So the more acidic the solution is, the more conductive it will be. That’s what the pH meter depends on.
In order for electricity to flow around a circuit, it must be complete. A pH tester circuit is completed by the test sample. The sample soil comes into contact with two electrodes which are found on the probe.
An electrode is a part of a circuit which comes into contact with non-metallic elements. The electrons travelling around the circuit are attracted to the electrodes’ membrane.pH meters have two electrodes, a glass electrode and a reference electrode. The glass electrode has a permeable membrane made from specialised glass, which houses a chemical solution and a silver-based wire. The reference electrode is also made up of a wire in a chemical solution.
The reference electrode is stable and works as a buffer and a reference against which the other electrode can be compared, and the pH determined.The glass electrode attracts the hydrogen ions. This then creates a small voltage which can be compared to the reference electrode.
The voltage difference between the two electrodes is then sent as a signal to the indicator, which is translated into a pH reading.For analogue pH meters this signal acts upon an electromagnetic coil which causes the needle to rotate about its hinge and give a pH reading on the scale.Digital pH meters require an analogue-to-digital converter to produce the number displayed on the LCD screen.
The reference electrode is calibrated before the devices are sold, which means it is set at a certain pH (generally 6.86 – close to neutral). Calibration is usually set using a buffer solution with a known pH, which the device can then be altered to.
Most basic soil pH meters cannot be calibrated after purchase. However, they can be placed in a buffer solution to check the device is indicating correctly. Buffer solutions are not widely available and can cost more than the meter itself, so this test is not usually deemed necessary.
The sensor results may be affected by temperature, but pH itself is temperature-dependent and so the results are a true reflection of these changes. However, the probes may also have slight discrepancies determined by temperature. These will be minimal but should be considered if an unexplained change occurs.
How do you use a soil Ph meter?
1，Clean the prongs of the tester with distilled water and a clean cloth before use, and between uses. This will keep the readings from being affected by the pH of a previous test or tap water.
2，Insert the prongs into the soil you wish to measure. The first reading that appears will be a pH, which is measured on a scale from 1 to 14, with 1 being the most acidic and 14 being the most alkaline. Seven is a neutral pH. Most plants will grow in a pH between 6 and 7.5. The soil tester measures pH levels from 3.5 to 8. Alter soil pH by adding limestone to raise it, or sulfur to lower it.
3，Press the button on the tester to view the moisture readings. The tester measures the percentage of moisture content in 10 percent increments, from no moisture to complete saturation. Most plants will want moist soil in the mid-range. Sand can be added to soil to increase drainage capabilities for excessively wet soil.