What kind of soil do I have?


Easy, at home soil tests...

Your soil is made up of three things: Sand, Silt, and Clay.

Sand is the largest particle, creating fast draining and well aerated soils with few nutrients. Clay is the smallest, making for wet and poorly aerated, nutrient rich soils. Silt is in between these two. Your soil has all of these, but the amounts of each greatly affect your garden.

You can figure out your soil type without even going outside. The most noticeable difference between sandy and clay soils is drainage. Think about the last time it rained – did the water disappear quickly, and did the soil dry out soon after? Or did puddles persist for days, possibly even flooding your yard? If you are on the fast draining end of the spectrum, you have a sandy soil. If you are on the moister side, you have a clay soil. If you’re somewhere in between, you have a silty soil. Here’s a hint: if you live in Chicago, you probably have a sandy soil.

If you’re still not sure, you can try any of these three tests to investigate further:

Texture by "Feel Test"

Wet the soil slightly. Rub it in between your index finger and thumb, or roll it around your palm with your index finger. Notice its consistency – is it very smooth and staying together well? Is it gritty and crumbling a little? If you noticed smoothness, it is a clay dominated soil. If it felt gritty, it is a sandy soil. If its in between those two, it’s a silty soil

Ribbon test

This one takes some practice, so don’t worry if it is difficult the first few tries. Place a clump of slightly moist soil on the inside of your index finger. Push your thumb along the clump, pressing it out into a ribbon. If it crumbles immediately, unable to form a ribbon at all, it’s sand. The longer the ribbon, the more clay there is. The ribbon will be at least 2” long for it to be a clay soil. Make sure not to overly wet the soil for this test, because that will make it more able to form a ribbon.

Jar test

This is the most involved of the tests, but will give you a more detailed answer, and is a fun little experiment that kids or scientifically inclined adults might enjoy. Get out a jar, glass cup, or any clear cylinder, and fill it about 1/3 of the way with your soil. Remove any obvious twigs, leaves, or rocks from your sample. Fill the rest of the of the jar with water, leaving a little room at the top. Next, shake the jar until the soil is a uniform sludge (this could take a few minutes), and then put it on a level surface and leave it alone for 24 hours. The particles will settle in order of weight, with sand forming in a layer at the bottom, silt in the middle, and clay at the top. After it settles, you will be able to see exactly how much of each particle your soil has.