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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.
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)
(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.
(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.
(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.
(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.
(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.
(Ca) is generally available in Ontario soils. Calcium deficiencies only really occur in sandy and/or highly acidic soils.
(Mg) is not readily soluble, making it available in most soil types.
(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.