How to Identify Your Soil Type: Sand, Clay, Loam, and Silt Soils

From beach sand to pottery clay, there is a huge spectrum of different soil types found on the earth’s surface. Identifying your garden’s soil type can help you properly amend and prepare the ground for different species of plants.

Fortunately, this doesn’t require any fancy tools or scientific equations. All you need are your hands, a little background knowledge, and a few soil samples from around your garden. 

Let’s dig into 7 simple steps for identifying your soil type and properly amending it for the plants you want to grow.

How Do I Determine My Soil Type?

The easiest way to determine your soil type is by grabbing a handful and feeling it in your bare hands. If it is very dry, add a few drops of water to get a proper analysis.

Analyze the feeling of the particles in your hand and try to roll it into a ball. While every soil has a different mineral makeup, these basic guidelines can help you identify the overall type:

7 Quick Steps to Identify Your Type

Soil type is defined by the proportions of sand, silt, and clay. These different-sized mineral particles determine the physical structure, which affects how water, nutrients, microorganisms, and plant roots interact with the below-ground ecosystem. 

For example, the rich loam most desired by gardeners is technically an equal proportion of sand, silt, and clay, with lots of organic matter. Loam is ideal for most vegetables and herbs because it provides a nice balance of attributes. Water drains through loam faster than clay, yet it retains moisture for longer than sand. Loam also has higher nutrient content and 

Follow these steps to identify your soil type and properly amend it for different plants:

Meet the Particles

Before you dig into categorizing your soil, it helps to understand the three different particle classes: sand, silt, and clay!

Don’t be intimidated by the scientific language— these particles are easy to feel and see with the naked eye! Soil texture is simply the proportions and sizes of these mineral particles in the ground. Different percentages of each particle determine different textures that are used to classify the type.

Sand

Sand particles are 0.05 mm to 2 mm in size. It may seem counterintuitive, but sand is actually the largest of the particles. Anything bigger than sand (2 mm diameter) is considered fine gravel. While we commonly think of sand as the tiniest grains on the beach, each particle of sand is considered a giant in the microscopic soil world. 

If we were to enlarge soil particles to a more conceivable size, sand particles would be like bowling balls. Imagine sandy soil as lots of bowling balls stacked on top of each other. There would be lots of air in between each bowling ball. This is called pore space. The large amount of pore space between sand particles is exactly why water and air pass through sand so quickly. 

When ocean waves flow up on a sandy beach, the water drains rapidly rather than puddling up. Similarly, heavy rain in the desert may cause a temporary flash flood, but the water drains and dries up super quickly. This rapid drainage is due to the large pore spaces between the desert sand particles.

Pure 100% sand is rare in a garden setting but is commonly found in deserts, dunes, and beaches. However, mixes of sand in soil are very common. For example, Florida, Georgia, Michigan, New Hampshire, and Nebraska have large areas of sandy soil. 

A texture with more than 85% sand particles would be considered sandy soil. If there is an even distribution of sand and clay, it would be called a sandy loam. We’ll cover more of the texture triangle below.

Silt

Silt is a medium size particle ranging from 0.002 mm to 0.05 mm in diameter. We most commonly find silt at the bottom of stream beds and river banks. Silt is smaller than sand but larger than clay. 

It’s difficult to see a single silt particle with the naked eye, but large amounts of silt are easy to identify by their slick, muddy texture in wetlands, streams, and river deltas. These particles are made up of fine rocks and minerals that form a dusty, slippery film. 

Silt is predominantly formed from erosion. As water, wind, and ice wear away at rocks, the tiny fragments are scraped against the sides of other rocks, grinding smaller and smaller as they move through the landscape. Silt usually accumulates in deposits along areas where water flows, especially where river deltas flow into larger bodies of water. 

The medium-sized pore space of silt means it doesn’t drain water as quickly as sand, but it doesn’t hold onto moisture for as long as clay. Silt offers a fair amount of air circulation and water retention without getting super bogged down by heavy rainfalls like heavy clay.

The pure silt found on river bottoms and in wetlands is composed of 80-100% silt particles. Silty soil is much more common, with blends of 50-70% silt with other particles. It is considered quite fertile and beneficial for growing a range of crops. Gardeners and farmers growing along the Mississippi River Delta are surely familiar with this type. 

Clay

The third and smallest particle is clay. Fine clay particles are smaller than 0.002 mm in diameter and cannot be seen with the naked eye. Even some microscopes are unable to focus on a single clay particle. These microscopic particles form crystalline structures in the earth and are most commonly found in soil horizons, volcanic deposits, and areas where rock has weathered away.

Remember our bowling ball (sand) and golf ball (silt) analogy? Imagine clay as stacks of teeny tiny sheets of paper. These particles tend to occur in very tightly packed sheets with almost no space between them. This is why clay gets so soggy and waterlogged when it’s wet.

There is very little pore space for water to drain through the “sheets.” Clay holds onto water longer than any other particle, and when it becomes oversaturated, the water often puddles on the surface because there is nowhere left for it to drain. When it dries out, clay tends to crack.

Pure clay or heavy clay soils contain 60% or more of clay particles. This type is very common in gardens around the world and, unfortunately, is one of the hardest to grow plants in. The tightly packed clay particles can easily become compacted and concrete-like, making it very difficult for plant roots to push through. 

If you have clay soil, you will instantly know just by trying to dig into it with your hand. It can be very hard and thick when wet and very cracked and brittle when dry. Read on to determine your soil’s clay capacity and how to improve the texture.

Loam

We hear the word “loam” in the garden world a lot, but what does it actually mean? Loam has an almost even blend of sand, silt, and clay particles, plus significant amounts of organic matter. Organic matter is decomposed plant or animal residues such as compost, manure, or mulch. 

When even percentages of sand, silt, and clay mix with organic matter, it creates that luscious, crumbly, rich soil we all dream of gardening in. Loams occur naturally in humus-rich topsoil of grasslands, including much of the Midwestern USA. 

Unfortunately, many loamy soils are now depleted or eroded due to large machinery tillage and synthetic chemical use. Luckily for you, you can transform almost any garden soil into loam with the proper amendment described below!

Collect Samples

To determine your soil type like a pro, first, you’ll need to collect samples. It’s important to analyze a handful of samples from each different bed or growing zone in your landscape.  Just because there is heavy clay in one part of your yard doesn’t mean it will be the same everywhere. Soils can vary dramatically across a 100-square-foot area. Huge changes in texture are often due to ancient glacial till or other erosion events that caused a big tumble of soil and rocks to settle in different places. 

The easiest way to take a sample is to simply grab a handful of soil from the upper four to six inches. If you regularly mulch the top of your beds with compost or another organic material, reach down below that layer to get a more accurate analysis of the zone where most plant roots grow. 

This process is different from soil testing, which involves taking a soil core or a big shovel full of soil and putting it in a bag to mail to a test center. Soil chemistry tests tell you the macronutrient and micronutrient composition. On the other hand, this sampling method determines your soil type based on the physical texture. You won’t be doing any chemical analysis. 

I recommend determining the type of each bed one at a time while you are standing there rather than collecting samples in bags for later.

Roll It In Your Hands

Take your handful of soil and begin rolling it around in your bare palm. Use your fingers to feel the texture of the dirt. If it is very dry, add a few drops of water so it is moist like a putty, but not soggy. 

Second, roll the soil into a ball. Play with the ball between your hands, or drop it on the ground to see if it holds its shape. Analyze the ball with these characteristics: 

• If the ball sticks strongly together when dropped, it is high in clay and/or organic matter.
• If the ball sticks together in your hand but falls apart when dropped, it is higher in silt.
• If it won’t form a ball at all, or the ball is very loose and breakable, it is high in sand.

Try the Ribbon Test

Once you’ve rolled the soil around a bit, you can use this test to get a more accurate idea of the amount of clay. The ribbon test is a classic field test used by scientists around the world. The premise is simple: higher clay soils form longer “ribbons” when squeezed between your thumb and forefinger. The key is making sure it is wet enough to play with, like putty or dough.

To do the ribbon test:

1. Grab another handful of soil and remove any debris. 
2. Gradually add a little water to the sample and mix it around in your hand.
3. Wet until you can easily mold it, and it has the texture of putty.
4. Squeeze the moist soil into a ball in your hand.
5. Use your thumb and forefinger to press the soil into a ribbon.
6. Begin pressing upward for the “ribbon” of soil to extend.
7. Notice if the ribbon sticks together and elongates or falls apart.
   1. If the ribbon is less than an inch long and won’t stick away from your fingers on its own, it’s a sandy or silty loam.
   2. If the ribbon is 1 to 2 inches long, it is around 15-30% clay, which is a loam or clay loam.
   3. If the ribbon is longer than 2 inches, it is more than 40% clay and considered clay soil.

The ribbon test is the easiest way to narrow down your clay content. This will help you estimate the percentage of clay, which you can later use to pinpoint the soil type. 

Try a Water Pour Test

The way that water drains through is an important indicator of the soil type and drainage capacity. Many plants are highly susceptible to root rot if their roots sit in waterlogged soil for too long. This “unofficial” test is something I often used on farms and in container gardens to determine if I needed to add more porous materials to my mix.

All you need to do is pour a generous stream of water from a bucket or hose. Notice what the water does on the surface:

• If it instantly drains through, the soil is well-draining and porous enough for most garden plants.
• If the water puddles up for a moment and then flows down within a minute, it could use a little more aeration materials.
• If the water forms a deep pool, the soil is compacted and/or high in clay, and you should amend it with a lot of drainage-improving materials before planting.

Drainage is particularly important in containers with succulents, cacti, tropical plants, or Mediterranean herbs. These plants really hate having “wet feet,” so it is important for the water to flow quickly through the l profile and pour out of the drainage hole. Puddling is a bad sign in a pot. You can improve the texture with compost, peat moss, vermiculite, or perlite.

Check the NRCS Soil Texture Triangle

The Natural Resources Conservation Service created the Soil Texture Triangle to make it easier for farmers and gardeners to identify their soil based on the percentages of each particle.

All the tests from above are simply estimates to get to know your soil more closely. Use all the info you’ve gathered to check the Soil Texture Triangle and narrow down the type.

Look on the NRCS Web Soil Survey Database

As a final checkpoint, you can explore the Web Soil Survey created by the USDA Natural Resources Conservation Service. This online map covers over 95% of America’s counties. Farmers, ranchers, and urban planners use it to determine how soils affect different agricultural and industrial activities. 

Alternatively, you can type in your address and mark it as an Area of Interest (AOI), then click on the Soil Map to see how different types overlap in your area.

Remember, your garden soil may be very different from the type on the database. This map gives you a general idea of the types found in your region.

How to Improve Texture

If your native soil makes it difficult to garden, you are not doomed to compact clay or gritty sand forever. Amendments are like organic soil conditioners that improve the texture very quickly.

You can turn a garden bed of heavy clay into a rich loam by simply adding a lot of compost and porous material like sand or perlite. Soils naturally take centuries of years to form as rocks erode and living things decompose, but you can amend your garden and improve the soil texture in the upper 6-12” very quickly. 

Here are the best soil conditioners for improving structure and performance:

Compost

Of course, the gold medal of amendments goes to compost! Compost is decomposed plant and animal material that microorganisms transform into carbon-rich organic matter. We often think of compost as a mulch or a soil blend ingredient, but you can use it to dramatically transform texture. 

Compost is special because it makes soil drain better while also helping it retain more water. Adding compost to clay soil will improve the porosity and aeration, while adding compost to sandy or silty soil will help it hold onto water for longer in hot weather.

When sourcing compost, be sure to check what inputs were used to make it. Compost made with manure will be higher in nitrogen, which can be great for heavy feeder crops like squash or brassicas but not so great for aromatic plants like herbs and flowers. Compost made with leaf litter or straw will be more carbon-rich and textured, which is great for longer-term water retention.

You may need to mix in large amounts of compost to start new beds when you’re first forming them. Once established, you can add a few inches of compost to the top of your beds every year. Some gardeners incorporate compost with a digging fork or shovel, but I prefer to layer it on and let the worms or microbes do the work of bringing it down to lower layers.

Peat Moss

Sphagnum peat moss is old decomposed organic material harvested from peat bogs in Canada. This amendment is amazing for raising the water-holding capacity, so your soil stays moist for longer without becoming waterlogged.

If you have sandy soil that dries out super quickly, peat moss is a great way to improve water retention. Mix peat moss into the soil at a ratio of about 1:1. 

Peat moss is slightly acidic and also beneficial for balancing pH. It helps acidify alkaline soil by bringing down the pH. 

It is important to pre-wet it because the material is hydrophobic. This means that peat moss right out of the bag will repel water. I recommend pouring the bag into a bucket or wheelbarrow, wetting it down with a hose, and using a shovel.

Horticultural Sand

If you need to dramatically improve drainage, this is the amendment for you! Horticultural sand or coarse sand is a blend of crushed minerals like quartz, sandstone, or granite.

It is sometimes called horticultural grit, one of the best materials for amending compacted or heavy clay soils to make them more suitable for plants that need extra well-drained soil. If your plants have struggled with root rot or other fungal infections, amending with sand can really help.

If you can’t find horticultural sand or it is too expensive, builders’ sand will also work as long as it hasn’t been treated with any chemicals. 

Perlite

Another quick way to improve drainage is with perlite. This is the most notable aeration ingredient in potting blends. Perlite sometimes looks like little Styrofoam balls, but it is actually a biodegradable material made from volcanic glass puffed at high heat. The puffed white balls retain some water, but mostly hold onto air and create lots of drainage. 

Perlite is extremely porous, making it great for potted plants, cactus or succulent beds, Mediterranean herbs, and seed starting mix. It is great for amending clay to improve drainage.

Vermiculite

Vermiculite is compressed flakes of silicate material that expand into sponge-like particles. It is often used alongside perlite in potting blends, but it holds more water and has smaller pieces than perlite does. 

Vermiculite is best for adding to sandy or silty soils because it helps them stay damp longer so plants don’t dry out. Vermiculite acts like a sponge and won’t add the same aeration as perlite.