Soil gets a bad rap. You can’t track it in through the house without hearing complaints, and if it’s found anywhere on you, you have to wash it off. When’s the last time you were celebrated for leaving dirty shoeprints on the floor? OK, so maybe the best place for it is OUTSIDE. It’s funny to think that the majority of the food we consume comes from what we consider, well, dirt. Soil is so much more than a dirty mess, so if you’re planning on growing anything it’s a good idea to know how to determine your soil texture.
Soil has 5 main components: Mineral particles, organic matter, air, water, and living organisms. When you’re creating the foundation for a garden, which is your soil, it’s important to make sure your soil has the important nutrients for your plants to grow, as well as the right pH levels. In addition, you’ll want to pay attention to the soil texture that you’ll be working with. Below we’ll discuss why soil texture matters, the different types of soil, and how you can determine your soil texture.
Why Soil Texture Matters
When you hear someone talking about soil texture, they’re not just referring to the look and feel of your soil. When people talk about soil texture, they’re talking about the 3 main particles that make up your soil – sand, silt, and clay and the percentage of each that is found in your soil. These are the inorganic solids that are then mixed with organic matter to create a soil that has the proper nutrients and pH levels to grow plants and produce.
Your soil texture matters because it will define what will grow well in your soil, and what will not. Soil texture is important because it affects your soil’s pore space – the space in between the mineral particles. This space allows for water and air. Water and air make up more than you might think of your soil structure – in fact, an ideal scenario would typically include 50% soil (45% mineral particles and 5% organic matter), and 50% pore space (25% air and 25% water).
Sandy soils have large particles that drain water too quickly and are low in nutrients, but are easy to work with. On the flip side, clay soils are made of very small particles that bind together that cause water to drain poorly and have less space for air, but they can be rich in nutrients. You want to find a balance between sandy and clay-like soils to allow for proper drainage that doesn’t drain too quickly, and still retains nutrients and air. Adding organic material to either extreme can usually offset the problems associated with each.
Soil Texture Types
Soil texture is determined by the mineral particle sizes it contains. Sand, silt, and clay – the mineral particles in the soil – are derived from rock that is broken down over thousands of years by environmental conditions. The ratio of sand, silt, and clay in your soil determine your soil texture type.
Sand is the largest particle that makes up soil texture. These rounded pieces allow for larger space between the particles. Both water and nutrients drain quickly from sandy soil. Plants that grow in sandy soil will need more water and organic matter/fertilizer. These particles are 2.00 to 0.05 mm in diameter and feel gritty.
Silt represents the middle size pieces. It’s smaller than sand but larger than clay. Individual silt particles are difficult to see because they’re so small. These particles are 0.05 to 0.002 mm and feel similar to flour when dry.
Clay is the smallest mineral component. These tiny flat particles fit closely together to create the greatest surface area of all soil types. Clay soil contains needed nutrients and also stores water that is slow to drain. It’s also the slowest to warm. These particles are smaller than 0.002 mm. They feel sticky in your fingers when wet and clump together. You can’t see the individual particles without a microscope.
Loam is a mix of sand, silt, and clay. While soil will typically include all three particle types, those that have more of a balance are considered as loam. I once heard the ideal loam texture is similar to moist chocolate cake. I wondered why I needed that visual comparison in my head, and I now wish you the best to remove it from yours as well 🙂
The USDA Natural Resources Conservation Service classifies soil types based on the percentage of sand, silt, and clay they contain. The Soil Textural Triangle below shows how those soil types are defined.
While there isn’t a perfect soil texture for all plants, since some plants prefer different conditions, the most common preferred soil type is loam. This includes roughly 40% sand, 40% silt, and 20% clay.
How to Determine Your Soil Texture
There’s a fairly easy test you can do to determine your soil texture, and it doesn’t require making too much of a mess. To determine your soil texture you can just need a jar with a lid, either a pint or quart size will do.
Mason Jar Soil Test
To perform the test you’ll want to go out to your garden area and dig about 6 inches down and fill your jar 1/3 to 1/2 with the soil sample. If there are any large stones or particles you can remove them.
Next, add a tablespoon or two of liquid dish detergent. This will help separate the particles that make up your soil. Then you can fill the rest of your jar with water, leaving about an inch of space at the top. After you screw the lid on you’ll want to shake the jar for 5 minutes. Then set it down in a spot where it won’t be disturbed for 24 hours.
Once the 24 hours have passed, you should see a layer of sand at the bottom, then a layer of silt, and finally a layer of clay. You can also end up with some dark organic matter at the top. After a few minutes, you should see the layer of sand settle at the bottom. The silt will settle after a couple hours, but the clay is what takes the longest.
Calculating your Soil Texture
You should be able to see 3 distinct layers after 24 hours. Once you’re able to see these you can measure the height of each layer, and divide it by the total height of your three layers to determine the percentage of sand, silt, and clay in your soil.
I recommend writing down each percentage of sand, silt, and clay that you have and then checking the soil texture triangle above to determine your soil type. For example, if you have 40% sand, 40% silt, and 20% clay your soil would be considered loam – the ideal soil texture. The picture below shows a sample from my garden that puts my garden bed in the loam category, borderline with sandy loam after sitting for 24 hours.
If your soil has a lot of sand or clay you can make adjustments. Adding organic matter can help over time, but if your soil is extremely sandy or clay-like you may prefer to start your garden using raised garden beds or containers, which can give your soil an ideal texture quality.
Do you know your soil type? Comment below!