Digging Up the Dirt On Soil Composition

The more you understand the composition of your landscape’s soil, the better your care and maintenance for that landscape can be. If you’re unsure of what to look for and why, then let Ewing guide you. Grab a microscope and a notebook, and let’s go outside and get dirty—or, that is, just read on…

Soil composition by the numbers
Minerals make up the majority of soil. These are sand, silt or clay, and their varying proportions are what give soils their texture and characteristics.

To say soil is just dirt is easy, but not entirely correct. Soil also contains living organisms—everything from insects and worms to fungus and bacteria—as well as organic material, air and water.

Typical soil is composed of:

• 45 percent minerals
• 25 percent air
• 25 percent water
• 5 percent organic matter

Remember, these percentages are just generalizations. A soil’s composition can change based on water supply, soil type or maintenance.

What is pH scale?
pH is a measurement of how acidic or basic a substance is. It runs on a scale from 0 to 14, with 7 being neutral (pure water has a pH of 7, and lemon juice has a pH of 2.2, for example). The optimum soil pH for growing turfgrass is between 6.0 and 7.0.

What’s the best pH for your soil? That depends on where you are located:

• For humid regions, soil pH should be 5 to 6.
• For arid regions, soil pH should be 7 to 9.

What if your soil is too acidic? What if it’s not acidic enough? You can adjust the soil’s pH by applying:

• Lime to raise the pH of acidic soil.
• Sulfur to lower the pH of alkaline soil.
• Gypsum to create no change in soil pH (but it will increase calcium and sulfur levels, and in sodic soil conditions where structure is compromised it can help the soil structure to break into small clumps).

Why is it so important to understand your soil’s pH level? Because pH is vital for a healthy soil environment, and you can’t maintain one if you don’t understand the pH levels at play.

Get to know your soil with a soil test
Your soil’s composition affects its intake of nutrients. If your landscape is suffering and you’re not sure why, then you should perform a soil test. This will tell you exactly what nutrients your lawn needs, watch this Ewing video to learn more.

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