If you cultivate vegetables of any kind, you will know how important the pH of your soil is.

• The pH value of your soil will indicate which crops or vegetables will grow best in your soil.
• The pH of soil is a measurement of the acidity or alkalinity of the soil.
• The scale for pH ranges between 0 and 14. A neutral measurement will read 7 and below 7 is acidic (sour) and above 7 is alkaline (basic).
• Most plants prefer a pH reading of between 5.5 and 7.0, but some plants are adapted to grow at levels outside this range.

WHY IS pH IMPORTANT?

• The pH level controls many chemical processes, like plant nutrient availability in the soil.
• The value of your soil, however, is not fixed and can be altered with adding additives like lime to make acid soils more alkaline, or sulphur to make your soil more alkaline.
• This should be calculated correctly by using a pH test that you can buy in a gardening or agricultural shop.

HOW TO TEST YOUR OWN SOIL?

This test is not very accurate and won’t give you a precise reading, but it is a good indication of whether you have acidic, alkaline or neutral soil. For an exact measurement you need to do a pH test.

You need:

• Clean soil from your field
• Water
• Clean container
• Vinegar
• Baking soda

Collecting soil for testing:

• Take a soil sample from a 10 cm depth in your garden.
• If you have a small field, you can mix the soil from 3 to 4 different spots in your field.
• If your field is larger, you have to do several different tests separately.
• Remove any rocks or debris, so you have only soil.

How to test:

Testing for alkalinity

• Put about 1 cup of soil in a clean, glass container.
• Mix in enough water to turn the soil into mud.
• Add about 125 ml, or half a cup, of vinegar to the mud mixture.
• If the soil fizzles, foams or forms small bubbles, your soil is alkaline.
• If nothing happens, you should test for acidity.

Testing for acidity

• Take another cup of soil in a clean, glass container (do not use the same mud as in the previous test).
• Mix in enough water to turn the soil into mud.
• Add ½ cup of baking soda.
• If the soil fizzes, foams or forms small bubbles, your soil acidic.
• If nothing happens, it means your soil is in the neutral range.

Source: https://www.thespruce.com/do-it-yourself-soil-ph-test-4125833 

Also read:
How to test soil life and health
How to use fertiliser to restore degraded soil