Sod

For other uses, see Sod (disambiguation).

Sod is the upper layer of turf that is harvested for transplanting. Turf consists of a variable thickness of a soil medium that supports a community of turfgrasses.^[1] In British and Australian English, sod is more commonly known as turf, and the word "sod" is limited mainly to agricultural senses. Sod is typically made with grasses that spread laterally through the soil and form a dense mat.

"Turf" redirects here. For an alternative expression, see Grass. For the Irish expression, see Peat. For other uses, see Turf (disambiguation). Not to be confused with Gender-critical feminism, also referred to by the acronym "TERF".

Turf rolls

Sod is used for establishing lawns or other greenways, in spaces like golf courses or sports stadiums. Typically, after construction or other kinds of landscape disruption, builders, owners and landscape specialist will place sod to establish a grass cover.

Sod is grown on specialized farms, where the grass, is grown for 12-18 months before specialized farm equipment cuts the sod from the top layer of the soil and makes it ready for transport. Sod is often cut in either squares or rolls, that make it easier for transportation and distribution. Different species of grass are grown in different geographies, because of the different climatic conditions. More recently, some producers have developed turf mixes that include wildflowers and other native plants.

Uses

Sod is generally used for lawns, golf courses, and sports stadiums around the world. In residential construction, it is sold to landscapers, home builders or home owners who use it to establish a lawn quickly and avoid soil erosion. Sod can be used to repair a small area of lawn,^[2] golf course, or athletic field that has died and is used as a quicker alternative to re-growing a lawn from seed.^[3] Sod is also effective in increasing cooling, improving air and water quality, and assisting in flood prevention by draining water.^[4]

Sod was historically used as a building material in various parts of the world, including settlers in the American grassland and in Scandanavia. Modern construction sometimes includes similar applications in Green roofs

Scandinavia has a long history of employing sod roofing and a traditional house type is the Icelandic turf house.

In the United States, following the passage of the Homestead Act by Congress in 1862, settlers in the Great Plains used sod bricks to build entire sod houses.^[5] This was effective because the prairie sod of the Great Plains was so dense and difficult to cut it earned the nickname "Nebraska marble". Blacksmith John Deere made his fortune when he became the first to make a plow that could reliably cut the prairie sod.^[6]

Different types of grass are used for sod installation.^[7][8]

Cultivation

Sod is grown on specialist farms and is usually grown locally within 100 miles (160 km) of the target market.^[9] Minimizing both the cost of transport along with the risk of damage to the product. The farms that produce this grass may have many varieties of grass grown in one location to best suit the consumer's use and preference.

Harvesting sod

Golf course sod

It is usually harvested 10 to 18 months after planting, depending on the growing climate. During cultivation, it undergoes fertilization, frequent mowing, watering, and in some cases vacuuming to remove the clippings. It is harvested using specialized equipment, precision cut to standardized sizes. Sod is typically harvested in small square or rolled rectangular slabs, or large 4 feet (1.2 m) wide rolls.

Prior to commercial sod cultivation, prospective consumers would pay farmers to cut and harvest their pasture.^[10][11]

Mississippi State University developed a hydroponic method of cultivating sod in 2006. For the limited number of sod farms that export turf internationally, this soilless sod may ship more efficiently and with less weight than traditional sod. Additionally, because it's not grown in soil, they don't need to be washed down to bare roots or sprigs, which shortens the time and cost required for export.^[12]

Impact on soils

One study of sod farms in Turkey found significant loss of topsoil and key nutrients when harvesting sod, more than other kinds of agriculture in the region.^[13]

Immediacy

In many applications, such as erosion control and athletic fields, immediacy is a key factor. Seed may be blown about by the wind, eaten by birds, or fail because of drought. It takes some weeks to form a visually appealing lawn and further time before it is robust enough for use. Sod largely avoids these problems, and with proper care, newly laid sod is usually fully functional within 30 days of installation and its root system is comparable to that of a seeding lawn two to three years older.^[14] Sod also reduces erosion by stabilizing the soil.^[15]

Many cultivars and some species can only be reproduced vegetatively rather than sexually (via seed).^[16] For these, sod cultivation is the only means of producing additional plants. To grow these varieties, turf farms use a technique called sprigging, where recently harvested sod mats are cut into slender rows and replanted in the field.

Species used

A typical roller mower operating on a sod grass farm

Fescue grass

Tall fescue

Tall fescue (Lolium arundinaceum) is a cool season grass type originating in Europe, commonly used as sod. It is moderately tolerant to both drought and temperature extremes. As such, it is especially popular in many temperate environments, known in the turf and landscaping industries as the "transition zone". In these areas, summers are too hot for most cool season grasses, while winters are too cold for most warm season grasses. Tall Fescue is well adapted to various soils, moderately shade tolerant, and somewhat resistant to most disease, yet vulnerable to Brown patch and Pythium blight. It grows most actively (and thus provides the most desirable appearance) in spring and fall, and requires moderate watering during summer. Due to its bunch type growth habit, which is unique among common sod grasses, it does not spread aggressively or invade adjacent areas once established. However, it also does not actively fill in bare spots, and periodic maintenance (such as overseeding) may be required to maintain a uniform surface. This bunch type growing habit contributes to a somewhat lower wear tolerance compared to Kentucky Bluegrass or Bermuda grass, making it less commonly used for purposes such as athletic fields.^[17][18][19]

Fine fescues

Fine fescues (F. rubra, F. rubra subsp. commutata, F. trichophylla) are less popular as sod than the tall fescues. As their names suggest, they exhibit much thinner leaf blades, and tolerate lower mowing heights than the tall fescues. They may be somewhat more resistant to common diseases and most generally prefer cool, shadier climates. Otherwise, their characteristics are similar, except for Creeping Red fescues (F. rubra), which spread via rhizomes and can form a dense sod. Fine fescues are generally used in mixtures with other grasses for shade and soil quality tolerance.^[20]

Kentucky Bluegrass

Kentucky Bluegrass (Poa pratensis) (also known as Common or Smooth-stocked Meadow grass) is widely used in sod production and lawns throughout cool season areas worldwide due to its cold tolerance, appearance, and ability to form a dense turf base. This species spreads via seed and underground rhizomes, allowing it to establish a strong root system that contributes to its natural sod-forming characteristics. Qualities that are especially important for commercial sod production and use.^[21]

Numerous cultivars have been developed to enhance specific traits such as drought resistance, shade tolerance, handling of disease, and overall turf quality. Cultivars such as 'Midnight', 'Barserati', and 'Blue Note' have consistently performed well in several trials, showing strong seasonal performance and resistance to common turfgrass diseases such as Grey leaf spot and Dollar spot..^[22]

Bella Bluegrass

Bella Bluegrass was developed by the University of Nebraska–Lincoln as a drought resistant grass with potential to help conserve water.^[23] It is the first commercial dwarf, vegetative bluegrass and is sold only as sod and plugs. The cultivar has pronounced lateral growth but has minimal vertical growth, only growing to about 4 inches in height. It grows in sand, clay, muck, and peat soils, and has seen some adoption across the northern United States.^[24]

Zoysia grass

Zoysia (Zoysia sp.) (Also known as Manila grass or Lawngrass in areas of the Far East) is a warm season turfgrass native to Asia and naturalized primarily in the Americas. Common species used for turf include Zoysia japonica and Zoysia matrella, including various hybrids of both.^[25] The grass spreads gradually by means of both rhizomes and stolons. A growth habit that typically results in a dense turf base that can suppress the establishment of some weeds. Zoysia's slow dense growth is also prone to developing a substantial layer of thatch. Which is a mixture of dead and living organic material at the soil surface that can slow water and nutrients from reaching the roots and may require periodic removal.^[26][25] This density also provides tolerance to extreme temperatures, drought, and traffic.^[27]

Because the grass germinates and grows slowly, establishment from seed is often unsuccessful and is typically planted as sod or plugs.^[28] Compared to many turfgrasses typical in cool season regions, established Zoysia generally requires less irrigation and fertilization during the growing season.^[27] Conversely, its slow growth rate means it is also slow to recover from damage or disease.^[25] As a warm season grass, it enters dormancy and turns light brown after the first hard frost and generally breaks said dormancy when soil temperatures consistently rise above 50 °F (10 °C).^[28]

Bermuda grass

Bermuda grass (Cynodon dactylon) (also known as Couch grass in Oceania) is commonly used in lawns and for sports surfaces across the southern half of the United States, parts of the Lower Midwest, and in other warmer areas around the world.^[29][30] It typically tolerates a wide range of climates where warm season perennials are regularly cultivated.^[31] Established bermuda grass has a network of shoots, rhizomes, stolons, and crown tissue together that usually form a dense plant canopy.^[32] This dense plant canopy can be used to propagate clonal varieties by sod, sprigs, or plugs.^[33][34] The aggressive nature of bermuda grass makes it not only a hardy turfgrass but also a challenging and invasive weed in land used for other purposes.^[35] Its two noted weaknesses are a low tolerance of shade and extended, prolonged periods of unprotected exposure to temperatures under 15 °F (−9 °C).^[36] Given the economic importance of bermuda grass (as a turf product, agricultural forage, and, at times, as an invasive weed), it has been the subject of numerous studies.^[37]

Celebration

Celebration is a dark green aggressive, traffic tolerant cultivar with high drought tolerance.^[38] The varietal is a hybrid of bermuda grass that was originally developed in Australia.^[39] Along with many golf courses across the southern United States, the Tampa Bay Buccaneers elected to install the cultivar in their stadium.^[40]

TifTuf

TifTuf is a commonly used hybrid of Bermuda grass developed at the University of Georgia - Tifton Campus, as part of its long standing turfgrass breeding program. The program has produced several broadly cultivated Bermuda grass varieties for many decades, such as Tifway 419, which remains widely used for sports fields and lawns.^[41][42][43]

St. Augustine grass

St. Augustine grass (Stenotaphrum secundatum) (also known as Charleston grass in South Carolina and Buffalo grass or turf in Australia) is a warm season, perennial grass that is widely used.^[44][45] The species is of disputed origin and is found throughout many subtropical areas of the United States. This grass is also commonly found and planted in built-up coastal areas across Australasia, Latin America, and low-lying portions of Sub-Saharan Africa.^[46][47]

As a tropical warm season grass, it has limited tolerance to cold weather, lacking the pronounced winter dormancy and/or rhizomatous growth traits typically found in most common turfgrasses. It typically enters semi-dormancy or suffers severe damage at sustained temperatures around 32 °F (0 °C), and does not resume active growth until soil and air temperatures regularly exceed approximately 60 °F (16 °C).^[48][49]

The vast majority of this grass is established using plugs or sod, since viable seeds are rarely available outside of research settings due to production challenges.^[50][51]

Floratam:

Floratam is a common, widely planted cultivar developed jointly by the University of Florida and Texas A&M AgriLife. It was officially released in 1973 in response to widespread damage from St. Augustine Decline virus (SAD) and the Southern chinch bug, though resistance to the insect has decreased over time.^[52][53] Floratam does generally not tolerant dense shade and can suffer permanent cold damage below 40 °F (4 °C). Like other commercial cultivars it spreads via stolons and must be planted as sod, plugs, or sprigs, as the seeds it produces are sterile.^[54]

Centipedegrass

Centipedegrass (Eremochloa ophiuroides) was introduced into the United States from southeastern Asia in 1916. It does well in the climate and soils of northern Florida and low lying areas of the Deep South. It is the most common home lawn grass in the Florida Panhandle.^[55] Centipedegrass is generally considered a slow growing, low maintenance warm season turfgrass, that has lower nutrient demands than a typical warms season grass. Due to this growth habit it typically requires less mowing and fertilization than several other turfgrass species.^[56][57] The species also usually holds its green color later into the fall than many other warm season turfs and tends to green up early in the spring.^[58]

TifBlair

TifBlair is a frequently planted cultivar of centipedegrass used for low input lawns and general turf areas in home and commercial settings. It's cultivated for said applications due to its very slow rate of vertical growth and low maintenance requirements.The hybrid was primarily developed in and named after Blairsville, Georgia and was released in the mid 1990s.^[59][60] TifBlair is also widely available as seed in addition to typical sod products.^[61]

Wildflower turf

See also: Natural landscaping

Wildflower turf (also called Bee or Pollinator grass) is a type of lawn alternative made up of a mixture of wildflower seeds. It is also mixed with common turf or native grasses in many commercial blends. The seeds are sown together and grow to form a lawn of flowers, rather than the monoculture of grass typical in a highly managed lawn. These type of plantings are generally considered a specialty turf and are rarely used in large scale sod production. This grass mix can be a low-maintenance and sustainable alternative to traditional lawns, as well as providing a habitat for beneficial insects and other wildlife. It often requires less watering and fertilization than traditional lawns.^[62] Wildflower turf can be used in the restoration of natural habitats, such as meadows, prairies, and wetlands. It is used on green roofs to provide a low-maintenance alternative to traditional green roof systems. Seed blends of this type can also help to capture carbon from the atmosphere, helping to mitigate the effects of climate change and to purify the air by absorbing pollutants and releasing oxygen.^[63]

Natural turf communities

Low growing vegetation is referred to as "turf communities" in areas where such growth is not common, as in moss-turf communities of sub Antarctica,^[64] some epifauna in the sea,^[65] coral reefs^[66] and, in New Zealand, as species-rich communities of plants under 5 cm (1.97 in) tall, on coastal headlands, dune hollows, rivers and lakes,^[67] where most of the natural cover was forest.^[68] A form of turf community is a herbfield.

Pest Damage

Disease

Turfgrasses suffer from a wide number of fungal diseases as well as some bacterial infections. Significantly improved sampling methodology for testing was introduced in 2023.^[69]

Insects and Wildlife

Many plants, including most grasses, are highly susceptible to white grubs and other insects that primarily develop in the larval stage below ground. The larvae feed on the roots of the host plant, reducing its ability to absorb water and nutrients needed to stay healthy.^[70] The damage is often worsened by moles, raccoons, birds, and other local wildlife that dig up the turf in search of them.^[71] The most common beetle species responsible include the European chafer, June beetles, Asiatic garden beetle, and Japanese beetle.^[72]

See also

• Gardening portal

• Lawn
• Cob (building)
• Divot
• Green track
• Groundbreaking
• Peat