Optimizing Soil Texture: Sand/Silt/Clay Ratio For Bermuda Grass

The ratio of sand, silt, and clay in soil—often referred to as soil texture—plays a crucial role in growing Bermuda grass effectively. The soil texture affects water retention, nutrient availability, and aeration, all of which are important factors for the healthy growth of Bermuda grass. Here’s how each component affects the growth:

Sand: Soils with a high sand content drain water quickly and are less likely to retain nutrients. Bermuda grass grows well in sandy soils because it tolerates drought conditions and sandy soils warm up quickly in spring, promoting early growth. However, sandy soils may require more frequent watering and fertilization to maintain optimal growth and green color.

Silt: Silt particles are smaller than sand but larger than clay. Silt helps retain moisture and nutrients better than sand, providing a favorable environment for Bermuda grass. However, too much silt can lead to compaction, which reduces aeration.

Clay: Clay soils retain water and nutrients very well but have poor drainage and aeration. While Bermuda grass can grow in clay soils, excessive clay can lead to waterlogging and root diseases. It can also make the soil cold and slow to warm in the spring, which can delay the growth of Bermuda grass.

If you don’t know what you have, some soil tests provide a texture analysis. Next, let’s talk about optimizing it.

USDA Soil Texture Triangle

Target Soil Texture Ratio For Bermuda Grass

For Bermuda grass, the ideal soil composition is a sandy loam, which typically means having a sand/silt/clay ratio of about 60% sand, 30% silt, and 10% clay. This type of soil provides good drainage while retaining enough moisture and nutrients to support healthy growth. Adjustments might be needed based on specific local conditions, but this is a solid starting point for most Bermuda grass lawns.

How To Adjust Texture

To adjust texture, focus on what you need more of (not what you need less of).

Sand

To improve drainage and aeration for Bermuda grass, add masonry or concrete sand, which you can find at landscaping supply stores like SiteOne. This type of sand is coarse enough to enhance soil structure without retaining too much moisture. Mix it with organic compost to avoid nutrient loss, and integrate this mixture into the top 6-12 inches of your lawn soil. This combination encourages the dense, vigorous growth characteristic of healthy Bermuda grass.

Silt

Enhancing your lawn’s silt content for optimal Bermuda grass growth might involve a bit more sourcing, as pure silt isn’t commonly sold in bags like sand or clay. However, some garden centers or landscape suppliers offer “garden loam” or “topsoil,” which typically have a higher silt content. Look for these products and incorporate them into your lawn’s top layer. This will improve the soil’s moisture and nutrient retention, creating an ideal growing environment for Bermuda grass.

Clay

In the uncommon scenario where your sandy soil needs more clay to retain moisture and nutrients for Bermuda grass, bentonite clay is a suitable addition. Available at gardening or landscape stores, add it sparingly to prevent compaction and drainage issues. Mix it well with organic matter and incorporate it into the top layer of your soil. Remember, adding clay should be done cautiously and only if necessary, as Bermuda grass generally prefers looser, well-draining soils.

This is directly from the USGA.

Here are the common names of each particle:

NameParticle DiameterCommon Names/Types of Sand
Fine Gravel2.0 – 3.4 mmPea Gravel, Crushed Gravel
Very Coarse Sand1.0 – 2.0 mmConcrete Sand, Paver Sand
Coarse Sand0.5 – 1.0 mmMasonry Sand, Builder’s Sand
Medium Sand0.25 – 0.50 mmPlay Sand, River Sand
Fine Sand0.15 – 0.25 mmFine Play Sand, Silica Sand
Very Fine Sand0.05 – 0.15 mmVery Fine Silica Sand, Pool Filter Sand
Silt0.002 – 0.05 mmSoil Particles, Silt Loam
Clayless than 0.002 mmClay Soil, Bentonite Clay
Total Finesvery fine sand + silt + clayCombination of Very Fine Sand, Silt, and Clay

The average particle size of sparkling white play sand is approximately 0.209 mm, meaning it can be <20% of the root zone. Sparkling white play sand is acceptable but not optimal. Standard play sand generally has particle sizes ranging from about 0.2 mm to 2 mm, meaning potentially half of it is over 1 mm and too coarse. Masonry sand ranges from 0.3 mm to 1 mm which is in the optimal range.

Type of SandAverage Particle Size (mm)Texture
Masonry Sand0.3 – 1 Coarse
Sparkling White Play Sand0.15 – 0.6 ❌Very fine and smooth
Therapy Play Sand0.3 – 0.6 ✅Fine and smooth
Sandbox Play Sand0.5 – 1 ✅Medium coarse, suitable for sandboxes
Kinetic Play Sand0.2 – 0.5 ❌Very fine and moldable
Beach Sand0.2 – 2 ❌Varies widely, from fine to coarse
Desert Play Sand0.1 – 0.4 ❌Fine, similar to natural desert sand

Big Box Store Options

Although it’s not economical to buy from big box stores in bags, if you’re shopping at big box stores, you can buy sand from the masonry aisle (inside), not the garden center (outside). Quikrete offers an “all purpose sand” which is used for masonry and concrete work which should be fine.

Anecdotally, Home Depot play sand has also been used for leveling in modest amounts but with the diameter being unclear, it’s recommended to stick to mason sand if available. Some play sand is suitable for leveling, depending on the particle size.

Why Not To Use Cushion Sand, Paver Sand, Leveling Sand

In a Bermuda grass lawn, sand is used to increase drainage and relieve compaction, however some types of sand are meant to increase compaction. They’re typically used as a base for a paver project or concrete slab.

Cushion Sand: This type of sand is often used as a base material because it compacts well. It is generally finer and can create a stable, compact base, which might make it more prone to compaction than mason sand.

Paver Sand: Paver sand is designed to provide stability under pavers, so it compacts well to prevent shifting. It typically has larger particles than mason sand and might compact more under pressure.

Leveling Sand: The compaction level of leveling sand can vary depending on its specific characteristics. It is designed to create a level base, so it may have some compaction properties, but it might not compact as much as paver sand.

    Sources

    https://droughtresources.unl.edu/soil-amendment-lawns-and-landscapes

    https://www.usga.org/content/dam/usga/images/course-care/2004%20USGA%20Recommendations%20For%20a%20Method%20of%20Putting%20Green%20Cons.pdf


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