Turfgrass Facts

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What is a turfgrass? | Turfgrass uses | Qualities of Grass Species | Turfgrass Nutrition

What is a turfgrass?

A turf is a perennial stand of living groundcover that can withstand traffic, grazing and mowing. Turf includes the entire system including the plant material, soil and thatch.
A turfgrass is any grass plant that can form a turf. Turfgrasses can be characterized by their temperature tolerance or ideal climatic conditions/zone. As such, they are divided into two categories which provide information about their ideal growing conditions and locations: cool and warm season grasses. 

Cool season grasses

Cool season grasses are found mostly in cool northern zones ranging from humid to arid or semi-arid (see climate map for zones), making them ideal grasses for Southern Ontario. While optimal growth occurs within temperature ranges of 15 and 24°C (60–75°F), growth will begin when soil temperatures reach 4.5–7°C (40–45°F). Cool season turfgrass are C3 grasses which recover quickly from winter dormancy at the start of a new growing season. However, these grasses will also regain dormancy if not irrigated during hot summer temperatures.  

Examples of cool season grasses:

Perennial ryegrass (Lolium perenne)
Tall fescue (Lolium arundinacea)
Creeping bentgrass (Agrostis stolonifera)
Velvet bentgrass (Agrostis canina)
Colonial bentgrass (Agrostis tenuis)
Creeping red fescue (Festuca rubra ssp. rubra)
Chewings fescue (Festuca rubra ssp. fallax)
Sheep fescue (Festuca ovina)
Hard fescue (Festuca brevipila, Festuca duriuscula, Festuca longifolia)
Blue fescue (Festuca glauca, Festuca arvernensis)
Kentucky bluegrass (Poa Pratensis)
Annual bluegrass (Poa annua)
Rough Stalk bluegrass (Poa trivialis)
Supina bluegrass (Poa supina)
Canada bluegrass (Poa compressa)

Warm season grasses

Warm season grasses are found primarily in warm southern zones, with moisture ranging from humid to arid. Optimal growth temperature ranges between 26–35°C (80-95°F), and shoots begin growth when soil temperature reach higher than 15°C (60°F). Warm season grasses are C4 grasses that have deep root systems, allowing them to withstand extreme high temperatures of greater than 37°C (100°F). 

Examples of warm season grasses:

Bermudagrass (Cynodon sp., Cynodon dactylon)
Zoysiagrass (Zoysia sp., Zoysia japonica, Zoysia matrella)
Seashore Paspalum (Paspalum vaginatum)
St. Augustine (Stenotaphrum secundatum)
Buffalograss (Buchloe dactyloides)
Centipede (Eremochloa ophiurioides)
Carpetgrass (Axonopus sp.)
Bahiagrass (Paspalum notatum

Turfgrass uses

The majority of turfgrass is employed for one of the three following uses:

Sports turf: Requires stands of turf that can withstand extreme amounts of traffic and soil compaction, while providing safe and relatively uniform playing conditions. Ex: school fields, municipal sports fields.
Lawn turf: Typically employed for its aesthetic value, this category of turf also provides a cooler surface than asphalt, concrete, etc., particularly in urban settings. Ex: Home lawns, commercial building grounds, cemeteries.
Utility turf: Used primarily to control surface erosion and ensure soil stability. Ex: Roadsides, airports grounds. The Turfgrass Outreach Project (TOP) aims to improve and maintain the quality of athletics fields and other sports turf in Southern Ontario.

What are the recommended turfgrass species for athletic fields in Ontario?

Turfgrasses for athletic fields usually are composed of a mix of species in order to combine the strengths of different grasses. In particular, the athletic field environment is often high sun and requires durable, quickly recovering ground cover. As a result, most fields consist of a high percentage of Kentucky bluegrass mixed with perennial ryegrass; species well-suited to athletic fields. These and other common species are highlighted below.

Qualities of Grass Species

Kentucky bluegrass is a perennial grass that has rhizomes, which allows it to form strong sod with good regenerative potential. Optimal conditions for this species are well-drained, fertile soils and full sun exposure. This species also forms a strong thatch that helps to protect the root and rhizome systems, keeping the regenerative parts of the plant out of direct contact with wear. As a result, Kentucky bluegrass can often re-grow after periods of severe wear and is well-suited to athletic field environments.

Perennial ryegrass:

This bunch-type grass forms a dense turf, has moderate wear tolerance, and cannot withstand extreme temperature conditions well. However, its primary advantage is a very quick germination period (approximately 7 days), providing rapid shoot coverage once planted. It is often mixed with the hardy Kentucky bluegrass to provide immediate coverage to an area while the slower germinating bluegrass becomes established. Perennial ryegrass is a cool season grass, best adapted to cool humid regions. 

Tall fescue:
Tall fescue is a coarse-textured bunch-type grass. It has good drought and wear tolerance, but has poor cold tolerance. It recently is being used on athletic fields in Italy where winters are not as severe as Ontario.

Turfgrass Nutrition

Nutrients required for the healthy development of turfgrass stands are divided into three categories, based on the nutrient's abundance in the plant, their importance to plant function, and abundance in typical soils. They are:
  Macro or primary nutrients – required in relatively large quantities
  Micro or secondary nutrients – required in medium quantities
  Nano or tertiary nutrients – required in very small quantities. 

Essential Plant Nutrients

There are 16 nutrients considered to be essential to plant growth as they cannot be created by the plant and must instead be harvested from the plant's environment. 

Nutrients requiring supplementation: 
Supplementation of these nutrients is required as part of a regular turfgrass management program.
1. Nitrogen (N) 
2. Potassium (K)

Nutrients sometimes requiring supplementation:
3. Phosphorous (P)
4. Iron (Fe)

Nutrients rarely requiring supplementation:
Artificial supplementation of these nutrients can result in toxicity effects when applied without testing existing nutrient levels of a playing field.
5. Carbon (C)
6. Oxygen (O)
7. Hydrogen (H)
8. Sulfur (S)
9. Calcium (Ca)
10. Magnesium (Mg)
11. Manganese (Mn)
12. Boron (B)
13. Copper (Cu)
14. Zinc (Zn)
15. Molybdenum (Mo)
16. Chlorine (Cl) 

Nutrients Requiring Supplementation

Nitrogen (N) is the most abundant and therefore most important mineral nutrient for turfgrass plant growth. It directly relates to fertility rates, and is often used synonymously by turfgrass managers. This is a result of nitrogen's stimulating effect on leaf and shoot growth, creating thicker turfgrass stands. While applying too little nitrogen may cause slow shoot growth, fewer leaves per plant and thin turf, chlorotic leaves and increased susceptibility to some diseases (such as rust, take-all patch, dollar spot, and red thread), too much nitrogen supplementation also has negative effects. By promoting too much leaf and shoot growth, root growth may be sacrificed, and stores of carbohydrates (substrate for photosynthesis) may be depleted. As a result, plants may experience decreased temperature and moisture stress tolerance and increased susceptibility to other diseases such as brown patch, anthracnose, and leaf spot.

Potassium (K) is an essential nutrient which promotes stress tolerance in turfgrasses. Proper potassium levels promote drought resistance, increases winter hardiness, and reduces disease pressure. Potassium addition is often estimated by this rule of thumb: add approximately half the required nitrogen, when clippings are being removed. For example, if nitrogen is added at a rate of 2kg/100m2 (4lbs/1000ft2) in a year, then 1kg/100m2 (2lbs/1000ft2) of potassium would be added. It is important to note that potassium can easily leach through the soil profile and into existing water tables, requiring potassium addition with great care. 

Nutrients Sometimes Requiring Supplementation

  • Phosphorus (P) is a nutrient required for the successful growth and expansion of turfgrass plants. In particular, it plays a big role in the growth of root systems, and by extension shoots and roots; if a root system is smaller, the plant will produce smaller shoots and leaves. Phosphorous remains relatively immobile in the soil, meaning P levels can be easily tested by soil labs. This nutrient is generally added in greater amounts during the establishment phase of a plant, to ensure that newly developing plants have access to phosphorous and can therefore develop strong root and shoot systems.
  • Iron (Fe) is a micronutrient usually in sufficient supply in soils. However, in some instances plants may become chlorotic as a sign of iron deficiency. A similar yellowing effect can be caused by nitrogen deficiency, but can be differentiated by clipping yield: low yield indicates nitrogen deficiency while a high or normal yield indicates that the turfgrass stand may require iron supplementation. 

Nutrients Rarely Requiring Supplementation

  • Sulfur (S) is often classified as a secondary nutrient and can be sourced from soil or rainwater. In Ontario, soils tend to be low in sulfur. However, sulfur is commonly found in rainwater due to industrial pollution of water systems. With the exception of northwestern Ontario our rain water will supply enough S to the turf. 
  • Calcium (Ca) is generally available in Ontario soils. Calcium deficiencies only really occur in sandy and/or highly acidic soils.
  • Magnesium (Mg) is not readily soluble, making it available in most soil types.
  • Manganese (Mn), Boron (B), Copper (Cu), Zinc (Zn), Molybdenum (Mo), and Chlorine (Cl) are all considered micronutrients that are usually readily available in soils, as the required amount of these minerals is extremely low. It is important to note that toxicity effects may occur if overuse occurs without testing existing nutrient levels through a soil lab.