How to Calculate Moisture Content

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Things You'll Need

  • Pencil

  • Paper

  • Scale

  • Small metal container

  • Food dehydrator or oven

  • Oven thermometer

  • Calculator

  • Compost materials such as grass clippings or dead leaves

Knowing a soil's water content can be an important factor in determining how often and when you water a garden or field. Soil content can be estimated by the feel of a soil sample, but for a more exact estimate, you can calculate the moisture content of soil using a specific equation.

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Step 1

Weigh a small metal container. Write down this weight.

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Step 2

Place 350 to 400g of soil into the container. Write down this weight.

Step 3

Dry the sample of soil in an oven or a food dryer for 24 hours at 110 to 120 degrees Fahrenheit.

Step 4

Place the dried sample in the metal container again and weigh the sample. Subtract the container weight from your total in step 2 to get solution A. Then subtract the container weight from the dried sample to get solution B.

Step 5

To arrive at the total of moisture in soil, use the following equation where soil moisture is solution C. {(A-B)/A}*100=C. In other words, subtract solution B from solution A and divide the total by solution A. Multiply the answer by 100. The total that you receive is the moisture content of the sample.

The moisture content is reflected as percent moisture on a weight basis.

Tip

Keep the soil samples between 350 to 400g. Larger samples require too much time to dry while smaller samples will give you inaccurate results.

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