An Easy Way to Check Soil Texture Type
Last week I performed a quick home soil texture test to help me better prepare for spring planting. This kind of test can help you determine the best plants your garden is naturally suited for, or what basic soil additives you may want to acquire if you wish to change that.
At this time last year, my garden beds were a small lawn with two very poorly placed trees and two very overgrown rose bushes. Through a series of incremental changes, I was able to trim back or uproot the un-cared for growth, and sequester much of it in carbon heavy berms at the base of my garden beds. I later mixed in vines and compost, pine needles and downed leaves, and even a few bags of top soil from the gardening store to create the beds I’ll be growing in this season.
While my subjective observations of the garden beds are that they are full of rich looking dark soil (albeit, with some unsightly rotting branches peeking through here and there), I wanted to collect some more objective data to track over several growing seasons in this space.
For the sake of folks who are new to this kind of work, I’ve written out exactly how I did it below.
All you need for this soil test are a garden trowel, one mason jar for each section of garden you want to test, pen and paper, tape, and a ruler or measuring tape.
First you’ll want to label each jar so you remember which garden bed its sample will come from. Next, you’ll want to use your trowel to dig down several inches into the bed in order to gain a good cross-section of the layers your plant’s roots will be tapping into.
You’ll want to fill each sample jar about two-thirds full with the soil sample. After that, you’ll top off your jar so that it’s almost full of water, leaving some room for things to be shaken and re-settled. Then you’ll do just that: shake your jar to mix up the water and soil sample. And then once it’s good and mixed, set the sample aside for about 24 hours.
Three Soil Components to Look For
Once your sample has had enough time to settle, you’ll be identifying how much of three different component layers are visible in the soil at the bottom of your jar. Below the water in your jar, you should be able to make out each of the three layers. If they aren’t clearly visible, let the samples sit for another day or so.
The top layer under the water will be clay. This is the least porous of the soil layers and it is made up of the smallest particles. When wet, it will expand, but then when it dries, it will often shrink and crack.
The layer directly under the clay will be silt. This is where all the medium-sized particles in the soil go. Like clay it is also difficult for water to drain through this kind of soil.
Lastly, underneath the silt we can find sand. This is where the largest and rockiest soil particles settle. It is also the most porous, which allows water and air to enter very easily.
To calculate how much of each soil type you have in your sample, you can tape a piece of paper to the side of your jar, and then mark out where each layer begins and ends. Next, measure the distance from the top of the highest layer to the bottom of the lowest layer. Then measure out the distance from the top to the bottom of each layer. Divide the measurement for each layer by the total measurement of the sample to calculate each layer’s percentage.
For example, if I have a total sample height of 2.75” and a silt layer size of 1.25”, I would calculate 1.25/2.75, and then multiple the answer by 100 to get an answer of ~45%. This means my sample is about 45% silt soil.
Once you have calculated the percentages for each layer, you can use this free calculator on the USDA website to chart your soil texture like I did in the triangular grid image above. You can adjust the color it will chart it with if you have multiple samples to track.
For most garden beds, you will be aiming for a loamy or sandy loam soil texture. If your sample isn’t there yet, you may need to mix in more compost or other soil types from elsewhere in your yard or a gardening supply store before you start planting.
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Pat Mosley (NC LMBT #16882) is a licensed massage and bodywork therapist in the Winston-Salem area. His work is rooted in compassionate touch, permaculture, and deep ecology with the resilience of all Earth's children in mind. Connect with him via email to email@example.com