How to measure the pH of the soil

How to measure the pH of the soil

To measure the soil pH or the soil to put in the pots you can use litmus paper, distilled water and test tubes (or small plastic containers). The alternative are the meters (analog or digital) of soil pH, which are not always reliable. In both cases the measurements will not have the precision to the thousandth of an analysis laboratory, but will tell you just enough to associate the right soil-soil with the plants and correct it when needed.

Measure the pH of the soil however, it can be useful and, let's face it, even fun. In this article we will give you all the detailed instructions, step by step, on how to prepare the soil sample to be analyzed and how to perform the pH measurement with economical methods or with pH meters.

Soil pH

First two background information. The pH is the measurement scale (from 0 to 14) of the basicity or acidity of a soil or solution referred to the concentration of hydrogen ions. The half-scale value, pH = 7, corresponds to a situation of neutrality and is for example that of distilled water. Values ​​of soil pH higher than 7 indicate a 'basic' soil, values ​​lower than 7 indicate an 'acid' soil.

Why measure the pH of the soil? If your plants in the garden or in pots grow well spontaneously, it means that the soil is the right one and you don't need to complicate your life. Ditto with potted plants buried in a universal soil. Most cultivated soils and all 'universal soils' have a neutral pH and this is the preferred situation for most plants.

A slightly more acidic level than soil pH it is important for acidophilic plants (heather, rhododendrons, azaleas, magnolia, camellia, blueberry) which just do not tolerate calcareous soils. Conversely, there are basophilic plants such as roses (which, however, tolerate all soils quite well as long as they are not too acidic), hyacinths, carnations and all legumes. In these cases, and if you have the good habit of preparing the potting soil yourself, it can be really useful to measure and monitor the soil pH; and possibly correct it with special processing, fertilization or irrigation.

Why is measuring soil pH important?

It is an understatement to say that:

  • acidophilic plants want more acidic soil (with low pH, below 7)
  • basolife want a more basic soil (with pH around 7 or higher).

This notion does not give an accurate account of reality because it eludes the real question. Why do some plants want an acidic pH reaction and others need a basically basic reaction? It depends on the solubility of the salts present in the soil.

Minerals such as calcium and magnesium, are more soluble in basic solutions (pH> 7), and are the most "required" by basophilic plants. Other nutrients such as iron, manganese and copper are more soluble in acidic solutions and do not dissolve in high pH water.

If you have ever heard of theferric chlorosis, it is a plant disease linked to the lack of iron absorption in those soils that are too calcareous. If the plants show suffering, it could be importantmeasure the pH of the soilso as to highlight imbalances.

Irrigating the soil with tap water increases the pH and generates suffering in acidophilic plants such as azaleas, rhododendrons, camellias ... It is for this reason that to irrigate we recommend the use of distilled water (specially purchased or obtained from the conditioner!) Or rain water.

Finally a curiosity: the common hydrangeas are a natural meter of soil pH. In fact, hydrangea flowers turn blue only in acid soils where the pH value maximizes the availability of aluminum, the element responsible for the blue color.

How to measure the pH of the soil

On the market there are several tests of soil pH, even for a few euros. The ways we have for measure the pH of the soil there are 4:

  • By contacting an analysis laboratory
  • Using litmus papers
  • Using reagent kits
  • Using a device called a pH meter

For measure the pH of the soil it is necessary to take some earth from the first 30 cm of soil, discarding the first 5 cm that are too exposed to the climate and external agents.

The soil used for the test must not be worked or fertilized recently, cleaned of radical residues and stones, crumbled as much as possible. In practice, before using it, you should sift it very carefully.

Check the pH of the soil with litmus papers

The litmus papers can be found in pharmacies, in the most well-stocked gardening shops or by taking advantage of online purchases. They cost a few euros and each strip is disposable.

How to use them? In an airtight container, one part of earth and two parts of distilled water are mixed (the unit of measure can be the coffee cup), shake well and when the earth has settled on the bottom, the litmus paper is dipped, which it must be left for the time indicated on the package. The litmus paper will take on a characteristic color based on the detected pH.

Soil pH measurement with reagent kits

The operation is more complex. The sample is taken as seen above and several drops of reagent are added to the bottle supplied (usually 5 or 10, it is indicated on the package). After adding the reagent, wait 15 minutes and observe the color that the solution takes on. The color should be compared with a scale supplied by the manufacturer.

In the photo above, a light blue bottle is shown with a pH between 8 and 8.5 as detected by the scale. In practice it is an extremely terrainalkaline!

A great kit forpH measurementof the land is on Amazon at a price of 7.50 euros, with free shipping. For all information, please refer to the official Amazon page: phBodentest.

The use of the pH meter

It is much simpler measure the pH of the soil with a pH meter, even if it is not certain that the measurement is more precise than the methods seen previously. However, measuring with a "pH meter" or "pH meter" is certainly more convenient.

Where to buy a ph meter? Again it can be found in agricultural supply stores. It is important to buy a device already calibrated for use in the soil. There are other meters on the market that are more suitable for liquid solutions, so it is important to choose ad hoc devices, equipped with a special probe to be buried in the ground. A good digital pH meter you can buy it on Amazon at a price of 29.99 euros, with free shipping. For all information, please refer to the official Amazon page: Soil, sensor with LCD display.