How to Monitor Moisture in a Compost


Maintaining moisture levels of 40 to 60 percent in a compost pile helps to create the ideal environment for composting. Too much moisture means there is little oxygen in your compost; that means decomposition will slow down and, most likely, your compost heap will begin to have a bad odor. Too little moisture will also slow decomposition. By testing the moisture level of your compost and learning what compost that is 40 to 60 percent water looks and feels like, you can monitor the moisture in your compost with little effort.

Step 1

Scoop out a small amount of compost from within the heap--just a spoonful or two will suffice--and place it on a scale that weighs in ounces or grams, such as one used for cooking. Record the weight to the closest ounce or gram. Be sure to use compost that comes from within the heap, not from the outer layer.

Step 2

Lay out the sample compost on a cookie sheet or baking pan and dry it in an oven set to 220 degrees Fahrenheit for 24 hours. Alternatively, lay it out in the sun to dry for two to three days.

Step 3

Reweigh the sample compost. This is how much your compost weighs without moisture.

Step 4

Subtract the weight of your dry compost (from Step 3) from the weight of your wet compost (from Step 1). The difference is how much water was in your sample.

Step 5

Calculate the percentage of moisture in your sample. Take the water weight from Step 4 and divide it by the total weight of the sample from Step 1. Multiply this number by 100. This, the percentage of moisture in your sample, is a good indicator of how much moisture is in your entire compost pile.

Step 6

Add moisture or dry materials (such as wood chips or cut-up newspaper) to adjust the moisture content of your compost, if necessary. Then measure the moisture of the compost again until it yields a result of 40 to 60 percent moisture. Once you have achieved this ideal moisture level, touch and feel the compost so you don’t have to conduct this test to know about how much moisture is in your compost.

Things You'll Need

  • Scale
  • Cookie sheet or baking pan
  • Calculator


  • Cornell University: Monitoring Compost Moisture
  • Cornell University: Moisture Content
Keywords: monitor moisture compost, measuring moisture compost, how to compost, compost moisture content, determine compost moisture

About this Author

Melissa Lewis has been a professional writer since 2005. Her work has appeared in various online publications. A former elementary classroom teacher and media specialist, Lewis is also a script writer, with a movie script, "Homecoming," she co-wrote currently in production. She holds a Bachelor of Arts in psychology.