What are the Types of Method to Measure Water Content in Soil by Field and Lab Method ?

WATER CONTENT :- Water Content can be determined using any of the following methods.

This is the most accurate lab test.
In this method moist sample of soil is fill in empety container of known mass (W¹) and after filling is known Weighed again (W²).
Container with moist soil sample is placed in temprature controlled oven for dying.
For inorganic soil, temparature is maintained between 105°C to 110°C for 24 hours.
For organic soil temperature is not increased beyond 60°C in order to avoid oxidation for organic matters.
For soil having gypsum, temprature is limited to 80°C in order to avoid loss of water of structural water.
In no case, temperature increased beyond 110°C because it results in destruction of soil solids causing losses of structural water.
After drying container with dry soil again weighd (W³) and water content is measured as follows.

W = weight of water / weight of soild × 100

= W² – W³ / W³ – W1 × 100

Oven Conditions:- 105°C to 100°C

< 80°C

< 60°C

This is field method used when oven not available.
In this method container with moist soil is placed in samd bath and is heated over stove.
As there is no control over the temperature it is not generally suitable for organic soil and soil with gypsum content.
Results obtained from this test are inaccurate because it may include structural water also.
Step of observation in this method are same as that of oven drying method.

In this method, methylated spirit is added to sample in order to increase, rate of evaporation during drying.
It is also a quick field method.
Because there is no control over temperature it is not suitable for organic soil and soils with high gypsum content.
Step or observation are same as that of oven drying method.

It is one of the quickest method to find water content of soil which gives the result within the 5 to 7 minutes.
It is field method.
In this method 4 to 6g ( fixed weight is taken due to calibration) of sample is placed in moisture meter and calcium carbide is added in it which reacts with the water present in the sample resulting in the formation of acetylene gas that exerts pressure over the gauge which is further calibrated to giver water content of soil is term of mass of soil

It is field method 2 steel casing are lowerd into medium.
In first casing radioactive material (Cobalt-60) is placed and in another casing detector is placed.
When radioactive material is activated it emits neutron which strikes with the hydrogen atom present in water and losses it’s energy, which is detected by detector placed in another casing.
The loss of energy of neutrons is further calibrated with water content of soil.