Study of pH of different types of soil

Exercise : Study of pH of different types of soil

Some nutrients become toxic in higher concentration. Therefore pH of the soil is an important chemical property of the soil. Plants thrive well in neutral or slightly acidic soils. The pH of the soil determines the types of soil organisms and also controls the solubility of different nutrients. The pH of soil ranges from 0 - 14.

a.  pH level 7        - Neutral soil

b.  pH level below 7       - Acidic soil

c.  pH level above 7       -Alkaline soil

Optimum pH for plant growth ranges from 5.5 to 7.

Most plants thrive best in neutral pH.  Slight acidity favours tree growth and forms forests.

Slight alkalinity is favourable for grasses and legume crops.

Aim:

To study pH of different types of soil.

Requirements:

Soil samples (from two different sites such as crop soil, garden soil, roadside soil, pond soil, river bank soil), test tubes, funnel, filter papers, pH papers of different range, distilled water, beaker.

Procedure:

Dissolve one tablespoon or 1 gram of soil from each soil sample in 100 ml of distilled water in separate beakers. Stir the solutions well and keep aside for half an hour to settle down the suspended particles. Filter off each solution separately in different test tubes. Dip a small piece of broad range pH paper on each of the solution. Match the colour of the pH paper with the colour scale given on the pH paper booklet. This gives an approximate pH.

Observation:

Record the pH of different soil samples in the observation table.

Inference:

Thus the pH value of different soil samples required for plant growth can be determined.

Precautions:

·        Wash the glassware thoroughly and get it dried before the experiment.

·        Dry the pH papers before comparing the colour with the colour scale.

·        Match the colour carefully and determine pH accurately.