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How to Measure Soil Moisture

How to measure soil moisture featured image.

Figuring out how to measure soil moisture can be difficult.

This post lists a few different methods for measuring soil moisture to get you on your way.

If you are planning a garden or yard work, knowing how much moisture is in the soil you are using can impact your success. There are a few different ways you can go about measuring the soil moisture to determine what steps need to be taken.

Below is a list of a few different methods for how to measure soil moisture.

Method 1 – Rough Estimate

If you do not need a precise measurement, there are a few ways to see how moist your soil is by simply looking at it and feeling it. If you stick your finger into the soil a couple of inches and it feels dry, it probably is. Another sign of dry soil is when it falls right off of your finger. On the other hand, if it sticks, it likely has a decent amount of moisture.

When you squish some of your soil in your hand, does it stay together or instantly separate? Moist soil will maintain shapes where dry soil will not. If the soil is very dry you will be able to brush it off of your hand easily.

You can also do a visual inspection.

Dry soil often looks lighter and very compact. Wet soil often looks muddy and will often have moss growing in it.

This is a great sign that your soil is at the ideal moisture level for plant growth. It is important to know what type of soil you have and what it “normally” looks like in order for this to be an effective method.

Method 2 – Use a Simple Moisture Probe

It is surprisingly easy and cheap to get a tool to measure the moisture in your soil. They can be found at most local hardware stores. If you do not need a lot of extra features, a traditional probe that has a scale indicator can be purchased for as little as $10. You can get even fancier ones if you need and don’t mind paying extra. For people that need to know the temperature and pH level of their soil, there are digital moisture probes that can cost anywhere from $50 to over $100.

Using a moisture probe is very simple. You simply press it into the ground and then read the results in a few seconds. If your probe is digital, it will pop up with a number. If not, you will want to watch for when the needle stops moving to determine your moisture content. It is a good idea to test more than one spot in your lawn or garden.

The scale on these probes range from 1 to 10, with 1 being very dry and 10 being very moist. If you are not sure what level your plant will thrive in, aim for around a 5. When your soil is too dry, it is very easy to water it. If your soil is too moist, however, you may need to set up an irrigation system, which is a bit more complicated.

Method 3 – The Gravimetric Method

If you want a very accurate number and don’t mind putting some work into it, you can try this more scientific method. You will need to be able to weigh small samples of soil in order to be successful with this. All you need to do is scoop up some soil and weigh it. Next, set your oven to 221 °F and let the soil sit in it for a full 24 hours. You will then measure the soil again. If the weight difference is minimal, you have dry soil.

A bigger weight difference indicates moist soil.

To determine what percentage of your soil is water, subtract the dry weight from the weight in the soil. Next, divide your number by the dry weight. Finally, multiply that number by 100. Be sure to work in grams for this. The number you get is the percentage of water in your soil.

Method 4 – Use a Tensiometer

For those who like science, you can purchase this gadget online for between $70 and $200. You insert it into the soil at the same depth as your plant’s roots. The gauge on top will tell you how much water is available for your plants to “drink.” A low water tension, usually 10 or less, indicates too much water is in the soil. If the water tension is high, between 60 and 80, it is a good idea to water your soil. A tensiometer measures in centibars.

Final Thoughts

Whichever way you choose to measure your soil moisture we hope you feel ready and confident enough to get out there and measure some!

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