6 Different Types Of Dirt And How To Maximize Your Native Soil For Better Harvests
Depending on who you talk to, there are between four and six different types of soil. What everyone does seem to agree on, is which soil type is best for your garden.
Clay, silt, sand, loam, chalk, and peat are the six main types of soil throughout the world. Each type has different properties and compositions, but you can amend any native soil to make it workable. Loam consists of equal parts clay, silt, and sand and is the ideal growing medium for most fruits, flowers, and vegetables.
Read on to learn how to differentiate between the different types of soil, and why some types are better suited to certain plants. We’ll discover how to determine what soil type you have in your own garden, and discuss how you can amend your native soil for healthier plants and better harvests.
The 6 types of soil
Most native soil can be categorized into six different types, depending on the texture, nutrient makeup, and ability to retain water.
Not all gardeners are lucky enough to have loamy soil, which is the ideal growing medium for most annual vegetables, and fruit trees. An even mix of clay, silt, and sand, loam is characterized by a fine texture. Loam is a well-draining medium but doesn’t dry out too quickly.
Although loam is naturally rich in nutrients, you will want to amend loam with compost and balanced fertilizer regularly. Loam is quicker than other types of soil to warm up in spring, and its light weight makes it easy to work with a tiller or other tool. Use loam for seed starting, potting up seedlings, or transplanting–you can buy bags of loam at most garden supply stores.
Sandy soils are most common in coastal areas and arid regions of the Southwest, according to a map by NASA’s Earth Observatory. Sand is easily recognizable due to its gritty texture and high porosity. Sand is an easy native soil to work with, as it is quick to warm in the spring and easy to cultivate.
Because sand is so well-draining, what little nutrition it does hold frequently washes away. Growers with sandy soil will want to amend their beds at the beginning of every season with peat moss and organic compost.
Consider mulching permanent beds with woodchips, straw, or cardboard to help retain water during the hottest summer months. Annual vegetables and flowers can tolerate sandy soils that have been properly amended with compost or fertilizer.
Silt is the next best thing to loamy soil. Silt has a similar, soft texture with water-retention properties akin to loam. Silt is commonly found in areas carved out by glaciers, or in the low-lying floodplains of major rivers, so it is a growing medium rich in nutrients. Silty soil is also lightweight and easy to cultivate.
Silt doesn’t drain as well as sand, so add organic compost to increase soil porosity. Most annual vegetables and flowers do well in silty native soils.
Unfortunately, clay is a difficult native soil to work with. Clay becomes sticky when wet, but is more akin to concrete when dry. This impenetrable characteristic creates pockets of pooling water that do not drain well.
Clay is very easily compacted by machinery, vehicles, and foot traffic, over time creating a hardpan that is difficult to till or cultivate by hand. Clay takes longer than most native soils to warm in the spring, so seeds and transplants can’t be set out as early.
Texture and porosity aside, clay is rich in nutrients. Some dry area-tolerant perennials will tolerate clay soils, but annuals don’t reap any benefits from clay soils.
Clay is a common native soil in the Appalachian mountains, the Midwest, and the Southern United States. If you do have clay soil, use organic compost and lime to improve the composition of your soil over time.
Chalky soil is comprised of larger particles that give it a chunky texture. Chalk has a high rock content, which makes it difficult to cultivate. However, rocky soil does drain well, and with the proper amendments can be a fertile growing medium for some leafy greens like spinach, lettuce, and kale.
Peat is easily recognizable by its spongy texture and dark color. Peaty soil is primarily comprised of Sphagnum peat moss, commonly found in the wetland areas of Northern Canada and Alaska.
Peat is acidic, so you’ll want to add limestone and compost to raise the pH level and add valuable nutrients. Brassicas and root crops thrive in peat soils, as well as blueberries and strawberries.
How to find out what kind of soil you have
Now that you know about the different types of native soil, it’s time to find out what your own soil composition is so that you can work with your soil type, not against it, for a healthier garden.
The easiest way to estimate what soil type you have is to pick up a handful and make a fist.
- If the soil holds its shape, you have clay soil.
- If the soil holds its shape for a second and then crumbles, it’s very likely loamy or silty soil.
- If the soil doesn’t keep a shape at all, you’re working with sandy soil.
Web Soil Survey Map
If you want to dig a little deeper, you can use the interactive USDA Web Soil Survey map to virtually identify what your soil type is by using your home or farm address. The steps are simple:
- Open the webpage
- Click on the green “Start WSS” button.
- Using the “Area of Interest” tab on the left-hand side, use the drop-down menu to search an area by address. Alternatively, double-click on the map to zoom in until you see your area.
- Click on one of the two small “Define Area of Interest” buttons to draw the approximate border of your garden.
- Click on the “Soil Map” tab to pull up the information about your particular area.
Of course, you can always send a soil sample off to your local university or research center for more precise results about soil composition. First, call your local agriculture extension office–you may need to pick up a container or be walked through specific instructions.
For most soil tests you’ll want to use a shovel to dig a hole at least six inches deep. You can usually test as many areas as you want, but you’ll want to collect two or three samples from each area to get the best results. Package the soil and mail the sample to the appropriate address.
Knowing your native soil composition and understanding what adjustments to make is essential. Pay as much attention to your plants’ soil needs as you would to their lighting, watering, or fertilizing needs. Amending your native soil could make all the difference in your garden this year and for years to come.
Always take the time at the beginning of the season to amend your soil with the proper materials to improve its nutrition and composition. Consider cover cropping, crop rotations, and no-till practices when possible to build soil health and overall longevity.
Web Soil Survey - Home, https://websoilsurvey.nrcs.usda.gov/app/HomePage.htm. Accessed 7 July 2022.Miller, Douglas, et al. “Soil Composition Across the US.” NASA Earth Observatory, 8 January 2016, https://earthobservatory.nasa.gov/images/87220/soil-composition-across-the-us. Accessed 7 July 2022.