Water Content Test of Soil by Alcohol Method
Purpose
It is a rapid method of determining the moisture content. Though less accurate, it is more suitable as a field test. The method shall not be used if the soil contains a large proportion of clay, gypsum, calcareous matter or organic matter.
Apparatus
- Evaporating Dish– 10 to 15 cm in diameter.
- Palette Knife or Steel Spatula-having a blade 10 cm long and 2 cm wide.
- Balance – of sufficient sensitivity to weigh the soil samples to an accuracy of 0.4 percent of the mass of the soil taken for the test.
- Methylated Spirit
Procedure
- Clean the evaporating dish, dry and weigh (W1).
- Take appropriate quantity of soil specimen in the evaporating dish and weigh (W2).
- Pour methylated spirit over the soil at the rate of about one millilitre for every gram of soil taken so that the soil is well covered.
- Work the methylated spirit well into the soil with the palate knife and break up any large lumps of soil.
- Place the evaporating dish on a surface which will not be affected by heat and ignite the methylated spirit. Stir the soil constantly with the spatula or knife taking care to see that none of the soil is lost.
- After the methylated spirit has burnt away completely, allow the dish to cool and weigh it with the contents (W3).
Calculations
The percentage of water content shall be calculated as follows:
W = [(W2 – W3) / (W3 – W1)] * 100
Where,
W = water content present
W1 = mass of dish in g
W2 = mass of dish with wet soil in g
W3 = mass of dish with dry soil in g
Reference
IS – 2720 – Part – 2
does this method suitable for organic fertilizer or compost? thank you…
One can understand that it is not suitaible for organic soils and soils containing gypsum.But why this method is not suitaible for clay?
why we not preferred this method for organic soil specially soil containing calcium compound??
Because organic matter would burn, lose mass and overstate the moisture calculation. Similarly limestone type material can decompose and offgas with the same outcome.
The calcicum content or simply gypsum has loosely bound water of hydration also known as structural water. At the normal temperature of 110+-5 degree celcius will bring out that structural water. Hence this will give us false readings. So we want temprature not more than 60-80 degree celcius for such soils. In this method there is no controle over the temprature. Hence this method is not used for soil containing calcareous content.
Same for organic soil, at higher temperature than 60 degree celcius, organic matter will decompose and organisms will be killed. Hence this will not show the true water content for the organic soil. Hence this soils cannot be be anyalised by this method.
What is the need of Methylated spirit in this test?..
What is the need of Methylated spirit in this test?