How to Test Soil pH Using Natural Indicators at Home.
Soil pH in simple terms is the measure of the alkalinity or the acidity of the soil. A pH value measures the hydrogen ion concentration in the soil. Acidic soils have low pH and have high hydrogen ion concentration, while a high pH value shows the soil is alkaline with low pH concentration.
Soil pH mostly ranges between 3.5-10; in areas that receive high rainfall, the pH of the soil is in the range 5-7, in drier areas, it ranges from 6.5-9. We classify soil as either neutral, acidic, or alkaline depending upon their pH value:
Neutral-6.5-7.5
Acidic- less than 6.5, soils with a pH value below 5.5 are highly acidic
Alkaline-above 7.5
Why measuring soil pH is important.
A desirable pH range is important for the optimal growth of the plants, some crop plants grow best at pH values ranging between 6-7, while others prefer slightly acidic soils. When elements like Ca (calcium), Mg (magnesium), Na (Sodium), and K (potassium) gets replaced by hydrogen ions, the soil becomes acidic. Areas that receive high annual rainfall are characterized by acidic soils in compared to arid regions.
Measuring pH
Materials required for soil testing
1) Soil samples: Two soil samples were collected from two different sites. The soil samples were collected in a clear transparent bag and were labeled as A and B, respectively. Stones and clumps of soils were discarded during the collection of the sample to get better results.
2) Turmeric indicator (prepared by dissolving a pinch of turmeric in an alcohol-based sanitizer)
3) Deionized water and dropper.
Procedure:
1. An equal amount of soil was taken with the help of a spoon (or if you have a weighing balance, weigh 5g of soil sample) in a glass.
2. About 20 ml of deionized water was added to each glass and the soil sample was stirred continuously for about 2-3 minutes to form soil suspension.
3. Let it stand for about 5 minutes.
4. With a help of a dropper, the supernatant was collected for the experiment.
5. Add 5-6 drops of the supernatant to a bowl and add 2-3 drops of the turmeric indicator.
6. Turmeric is yellow with acidic soils while turns bright red with alkaline soil.
