In order to grow a successful garden full of healthy plants, it is essential to understand the type of soil that you are working with. The texture is one of the ways to classify soil, and it is a significant determining factor in many of the soil’s characteristics.
All soils do not have the same texture. There are 12 classifications of soil texture based on makeup. Soil is composed of clay, silt, and sand, and its texture is categorized by the ratio of these three elements.
This article will discuss the importance of soil texture and each element’s contributions to the soil’s characteristics. It will also explain two ways to determine your soil texture at home.
The Importance of Soil Texture
Soil texture impacts many of the soil’s other characteristics, including the following:
- Water Retention: A soil’s ability to retain water and drain excess water has an enormous impact on plant growth.
- Nutrients: The makeup of soil determines the nutrients available to the plant. Some mixtures of soil contain more nutrients than others, allowing plants to grow stronger.
- Root Growth: In order to grow, roots need a lightweight material that they can easily break through. If roots do not have enough room to spread out, the plant will quickly die.
- Workability: The ease of digging and working the ground is dependent mainly on the texture of the soil, which determines its weight and how easily it will become compacted. Having workable soil will save you time and effort when planting.
Types of Soil Textures
While each country has its own soil classification systems, most countries (and the United Nations Food and Agriculture Organization) recognize 12 types of soil textures.
The 12 types of internationally recognized soil texture are as follows:
- Sandy Clay
- Sandy Clay Loam
- Sandy Loam
- Loamy Sand
- Silty Clay
- Clay Loam
- Silty Clay Loam
- Silty Loam
Soil is placed into one of these categories based on its ratio or percentages of clay, silt, and sand. Each of these materials contributes different characteristics to the soil. The more of an element in the soil, the more it will take on those characteristics.
Although different plants require different textures of soil, most plants do best in a combination of all three materials. For more information on this, check out my article on the ideal soil texture for planting: The Ideal Soil Texture for Planting Explained
Clay is the Densest Soil Component
Clay is the densest of the three materials, which can make it difficult for roots to grow. Roots are relatively weak, especially at the beginning of a plant’s life, and they do not have the power to dig through soil that is too dense.
Clay can hold a lot of water but does not provide good drainage. Poor drainage means that water will sit next to the roots for too long, leading to a lack of oxygen and, ultimately, root rot.
Additionally, clay does not contain many nutrients, making it difficult for plants to survive in clay alone.
Silt Is High in Nutrients and Minerals
Silt is made up of tiny particles of rocks and minerals. In the United States, silt is composed primarily of siltstone, but around the world, there is a wide variety of silt makeup. Silt generally contains lots of nutrients and minerals, which makes it a good option for growing produce.
Silt has good water retention but poor drainage, which gives it the tendency to become muddy. To learn more about this, check out my article addressing whether you can grow plants in mud: Can You Grow Plants in Mud? What You Need To Know
Sand Provides Less Resistance and Retains Water Poorly
Sand is a very easy material for roots to grow in, as it provides little resistance. However, this also means it cannot hold the roots as tightly, providing less plant stability.
Sand maintains aeration well, but it does not absorb water. This poor retention limits the plant’s access to water to rainfall and external watering. Additionally, sand contains no nutrients, so very few plants can survive in 100% sand.
How To Determine Soil Texture
The most accurate way to determine soil texture is with a microscope. Silt and clay particles are very small and cannot be seen with the naked eye. That being said, several methods of testing soil texture can give you a general idea of your soil’s makeup.
Using the Layer Method to Determine Soil Texture
For this method, you will need to have a clear container with a lid. Mason jars are a popular option because their lids screw on tightly. You will also need a small amount of Borax or Calgon, often used as laundry additives. If you do not have this, you can still do the test. Still, using it will be more accurate and help the water to clear completely.
- Take a sample of soil. You do not have to dig very deep to obtain a soil sample for this test. Dig about 5 inches (13cm) down and collect 1 cup (250mL) of soil. The soil should fill ¼ of your container, so you may need a little less for a smaller jar.
- Remove excess matter. For this test, you need as clean of a sample as possible. Sift rocks, pieces of grass, roots, leaves, and even worms out of your sample.
- Place the soil sample in your container. Once sifted, place your soil into the container, filling it about a quarter of the way.
- Add water to the container. Next, add room temperature water to the soil until the jar is about ¾ of the way full. The water should not fill up the jar completely.
- Add Borax or Calgon to the container. Sometimes there will be problems with this test; the clay may never settle at the bottom of the jar, making it difficult to get an accurate measurement. Adding Borax or Calgon helps the clay to separate from the water for precise readings.
- Shake the container. When you shake the sample, you need to break the soil down into its smallest particles: clay, silt, and sand. You should shake your container vigorously for at least five minutes to ensure proper breakdown.
- Let the container sit for 1-2 days. It does not take long for the sand and silt layers to settle to the bottom of the container. The clay, on the other hand, takes much longer to settle. After a day, you should check your container. When the water becomes clear, you will know when the clay is fully settled.
- Measure the layers. Once each material has settled, you will have three distinct layers in the container. The bottom layer is sand, followed by silt, and clay will settle on the top. Measure the thickness of each layer to create a ratio or percentage of each substrate.
- Analyze the results. You will need to use a soil texture triangle to determine your soil texture. The Queensland government provides one here. Use the percentages to find the intersection of your clay, silt, and sand. The intersection of these lines will tell you which of the 12 types of soil you have.
Gauge Texture By Feeling the Soil
Another way to get a general idea of the type of soil you are dealing with is simply to feel it. The USDA has made a simple flowchart that walks you through several steps to classify your soil.
You will need 5 tsp (25g) of soil for this test. Like the layer test, you should remove any excess materials and add water to make a putty. You then move through the questions based on your answers, which will each lead you to another question group.
Please note that since this is a qualitative test, it will only give you a very general idea of what you are working with.
Other Soil Classifications
Aside from texture, there are many other ways to classify soil, including:
- Soil Structure
- Soil pH
- Soil Fertility
- Soil Toxicity
Like texture, these characteristics play an important role in creating an optimal environment for your plants.
There are 12 types of soil textures, which combine clay, silt, and sand. The quantity of each of these components determines the soil’s textural properties.
Clay has few nutrients and high water retention but poor drainage. The density of clay makes it difficult for roots to become established.
Silt has high nutrient levels, good water retention, and poor drainage. It does not provide much resistance to roots.
Sand has no nutrients or water retention but good drainage. It provides virtually no root resistance.
You can determine soil texture at home using a layer method or by feel.
To learn more about improving soil quality, you could read my other article here: How to Improve Soil Quality (The Ultimate Guide)