The soil pH is defined as the negative logarithm of the hydrogen ion activity. Mathematically, it is expressed as: pH=-Log[H⁺] and it ranges from 3 to 9,

Actually, the pH of soil influences on solubility of toxic nutrient elements in the soil and it gives idea about availability of soil nutrients to plants. At high pH values, availability of P, and most micro-nutrients, except B and Mo, tends to decrease.

Apparatus

·         Distilled water

·         pH meter.

·         Beaker

·         Buffer solution pH 7.0and pH 4.0

·         Grass rod

·         Graduated cylinder

·         Tissue paper

Procedures

·         Weight 10 gm of air-dry soil in a 100 ml glass-beaker

·         Add 100 ml of distilled water using a graduated cylinder to make a suspension of 1:10 w/v dilution.

·         Mix well with a glass rod, and allow to stand for 30 minutes.

·         Turn on pH meter

·         Calibrate it with buffer solution

·         Immerse the probe into prepared suspension and read the pH value

·         Remove the probe from the suspension, and rinse thoroughly with DI water in a separate beaker, and carefully dry excess water with a tissue.

References

1. George E., Rolf S., John R.; Methods of Soil, plant and water analysis;3^rd ed; p65

2.Sadhan C. Anand Dev G.; Handbook of Water, air and soil analysis; international E publication;2014

3.Haluschak P. Laboratory Methods of Soil Analysis Canada-Manitoba Soil Survey, April 2006