How to Measure Soil Humidity
When it comes to climate, grass only needs two things: warmth and moisture. Measuring soil humidity, or its moisture levels, is the most accurate way to gauge how much water is being held in the soil and how much is needed to help plants grow and make lawns healthy and green.
In-Field Sampling Test
The best way to measure soil humidity is through a soil test that requires in-field sampling. This simply means taking multiple samples from different areas of the lawn in order to see where the moisture lies and where it's needed.
- To start, select areas that are representative of each part of your lawn. Avoid taking samples from areas near low spots or ridges.
- With a small shovel, scoop a handful of soil and place it in a tight, plastic container or bag with an enclosure.
- Place the samples in a cooler so that it remains under moderate temperatures and retains moisture.
- Once you're home or at a lab, place around 25 grams of moist soil on the paper plate and record the weight of soil and plate. Remember to subtract the weight of plate from the total number.
- Dry the sample in a microwave or conventional oven and run it for 10 minutes.
- Weigh the sample and return it to the microwave for 5 minutes before weighing again. Repeat the process until the weight no longer changes. Wet samples may take around 20 minutes to dry out completely.
- Calculate the percentage difference between the original weight of the soil sample and the weight after 20 minutes of being microwaved. This should indicate how much moisture your soil has and allow you to compare it between the different areas of the lawn.
Since water is the first thing to evaporate when soil is placed under extreme heat, you can also gauge the overall humidity levels by how quickly the soil gets hot. Drier soil will experience temperature increases as it oxidizes the organic matter.
Do I Need to Test for Soil Humidity?
You should test for soil humidity if you've discovered numerous dry spots around your lawn or haven't watered the lawn in the past few days or weeks. However, you don't necessarily need to take the above steps to measure soil humidity if it's obvious that your soil is dry.
Other signs that indicate a dry lawn:
- The lawn has a grayish tinge.
- The grass blades have wilted and don't immediately recover after walking on them.
- The grass blades are folding up or curling up.
There are some sprinklers and irrigation systems that can be adjusted to detect how much moisture is in the soil and concentrate the distribution of water in areas that lack moisture.
While soil tests aren't always required to determine whether your lawn needs moisture, it can nevertheless provide accurate insight into the workings of your soil. You'll also be able to better understand your lawn and determine the nutrients and treatment it needs to be healthy and green.