Best Technical Merit Answers- March 2003
Following the success of the Technical Merit Award 2003, sponsored by Tillers Turf. Pitchcare have started to publish some of the best answers submitted to the monthly scenario questions. This month we have the best of March's answers. Next week the best answers to the April scenario question will be shown.
What are the main nutrients needed for healthy grass growth, and how do they affect the grass plant? What other elements are important and why?
1)The main nutrients required for healthy grass growth are Nitrogen (N), Phosphorous (P) and Potassium (K). A correct balance of nutrient will ensure that the turf plant is healthy and exhibits strong growth. Controlling the nutrient balance of the soil enables a Groundsman to influence:
1. Sward Density
2. Encourage desirable grass species
3. Discourage undesirable grass species and weeds
4. Improve colour and visual appearance of sward
5. Improve root growth
6. Strengthen sward resistance against disease, drought, and cold and harsh weather conditions.
7. Provide a uniform playing surface
Nitrogen is the key element, and is the one which will have most effect on greenness of leaf, ability to recover from damage, growth, resistance to disease, heat, cold, drought and density of root and shoot growth. Nitrogen is used in the formation of chlorophyll. Phosphorous promotes healthy rooting and tillering. A deficiency can cause a reduction in the plants ability to retain moisture. Potassium helps thicken the cell walls, giving greater resistance to adverse conditions and encourages rooting to increase wear tolerance. It is a catalyst in the process of photosynthesis.
Generally, the other elements regarded as most important to grass are Magnesium, Calcium and Iron. Magnesium is essential for the green colour of the plant, being a constituent of chlorophyll. Calcium is found in the grass cell walls, and is needed for cell division. Calcium can also neutralise toxic substances.
Iron is again essential for the green colour of the plant, being essential to the formation of chlorophyll. It is used as a catalyst in the reduction of nitrates and iron can reduce respiration and improve root development during times of drought.
2) Oxygen, Hydrogen and Carbon are 3 plant macronutrients required by plants that are available from the atmosphere and water. Nitrogen is the next most important plant macronutrient, closely followed by phosphorous and potassium. Sulphur and calcium are also required by turfgrass in higher amounts than 'trace elements'
Nitrogen is required by plants to produce DNA. Nitrogen is also very closely associated with leaf development. A Nitrogen deficiency and red thread can cause chlorosis of the leaf. Too much Nitrogen is associated with Fusarium. Nitrogen levels change often in soils and are hard to determine, therefore applications of nitrogen to the sward should match the rates of growth/ use so that there is a minimum of leaching (waste).
Phosphorous is used by plants and animals as it is a constituent of ATP, a high energy molecule, created by plants during the light dependant phase of photosynthesis. During the dark reaction of photosynthesis it is used to capture carbon and store it as a stable high-energy compound; such as glucose. Phosphorous is also related to root development and is applied to seedbeds to aid germination. Too much phosphorous can assist in Poa annua invading the sward.
Potassium is used by the plant for stomatal opening and is involved in making plants disease and drought resistant. Fruits and flowers will benefit from a sufficiency of potassium.
Altogether there are 18 essential elements required for growth. Some of these elements are only required in very small amounts and are known as trace elements. These elements play a small but vital role in the metabolism of turf grass, for example magnesium is the central element in chloroplasts, Calcium is integral to cell walls and iron is an essential element in the electron transport chain (part of photosynthesis).
If any nutrient, macro, micro or trace is deficient the plant will be very unhealthy, if one element is totally absent the plant will not live. All nutrients apart from those taken from the atmosphere are taken into the plant via the roots in solution.
Nutrients are available to a plant in three phases; deficiency, sufficiency and toxicity. The soil pH affects the availability of nutrients! Correct fertiliser management should ensure that nutrients are available to the plant in the phase where there is just sufficient of each nutrient, but not too sufficient as this is not necessary and is wasteful (could also cause other detrimental effects).
3)(N) nitrogen- affects shoot growth, root growth, shoot density,
colour, disease proneness, heat, cold and drought tolerance. Main nutrient required by grass.
(P) Phosphorus-influences establishment, maturation, rooting and reproduction.
(K) Potassium-influences rooting, drought, heat and cold tolerance, disease susceptibility and wear tolerance.
(Mg) magnesium-required for producing green colour in leaves, as it is part of the chlorophyll molecule.
Important in translocation of phosphorus, normally adequate soil supplies, although may be required for high sand specification
(Fe) iron-a micronutrient widely used as a turf tonic. Produces a dark green to blackening effect on turf. It assists in
chlorophyll synthesis. Acidifies the turf surface, improving disease resistance, reducing weeds and worms, discourages coarser grasses.
Two other main nutrients or macronutrients, calcium (Ca) and sulphur (S) and the remaining six micronutrients boron (B), chlorine (Cl), copper (Cu), manganese (Mn), molybdenum (Mo) and zinc (Zn) are all important to healthy grass growth but generally reside in most soils in adequate amounts. As always, a soil analysis is recommended for any suspected deficiency.
4)NPK major nutrients they are Nitrogen, Phosphorus and Potassium.
Ca. S. Mg still recognised as major but not in the amounts as NPK.
Cu. Zn. Mo. B. Fe. Mn. all are recognised as minor nutrients.
From the top
1. N = Nitrogen this helps with leaf development, cell division in the meristematic region. Lack of results in poor growth, yellowing and early maturation.
2. P = phosphate this helps in root growth. Most important has a role in the formation of nucleic acids and proteins. Lack of P results in poor roots and very slow general growth.
3. K = potash this effects enzyme activity and in turn osmotic pressure, plus the role of hardening the plant up. Lack of K results in slow growth in the meristematic region and poor hardiness.
4. Ca = calcium this helps with the formation of the cell walls. Lack of Ca can cause the locking up of other nutrients at low or high PHs.
5. S = sulphur this is the constituents of vitamins. Lack of S results poor young growth mainly in the meristematic region.
6. Mg = magnesium this is an element of chlorophyll. Also important in the function of enzymes. Lack of Mg results in chlorosis of the leaves and poor growth.
7. Cu = copper this helps with the constituents of enzymes, also important in respiration. Lack of Cu results in poor shoot growth and die back of shoots in the top fruit.
8. Zn = Zinc this is used in the enzyme systems. Lack of Zn result in malformation of leaves also chlorosis between the veins.
9. Mo = Molybdenum this is important in enzyme systems and importantly in nitrogen fixation. Lack of Mo results in reduced leaf size.
10. B = boron this helps with the movement of sugars in the plant. Lack of B results in die back of the meristems.
11. Mn = manganese this is found in the leaves and the seeds and is involved in enzymes. Lack of Mn results in the chlorosis of older leaves.
This is how and what I believe the nutrient do and what they are needed for in the grass plant. In my opinion from what I have learnt at college you have to know about the above together with soil nutrient analysis, then buy your fertilizers.