March Scenario answers.
By Dave Saltman
The March Technical Merit Award in association with Tillers Turf attracted 52 entries to the topical question. The question was:
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?
The best answers are below. The Judges have now made their decision for the best topical answer from these entries and so one lucky member is in the pot for the £2000 All-inclusive holiday. Remember that the judges are looking for the answer that best responds to the question set. This may not necessarily be a text book answer.
Each month a new set of multiple choice questions are posed, with each correct answer going into the monthly draw. In addition to these eight questions, a topical question, requiring a little thought will gain every entree the chance to win the Grand Prize.
The purpose of the Technical Merit Award is to share knowledge and help explain some of the many topical questions that we encounter in our profession. Our philosophy has and always will be ' A problem shared is a problem solved'.
I hope that you have enjoyed the April questions this month so good luck with May.
The answers below are not in any order of excellence, it's just how I picked them out of the database to be viewed by the judges. Feel free to e-mail me your best first, second and third answers at firstname.lastname@example.org. The answers are not necessarily completely correct in their assessments, particularly in chemical suggestion and expert advice should be considered prior to application of any chemicals.
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) Nitrogen this is the key element in grass nutrition there must be sufficient nitrogen available for colour, vigour and general growth.
Phosphate needed for early stages of growth of root and shoot growth.
Potash is essential in promoting healthy growth, will improve root growth, and drought and cold hardiness.
Magnesium needed for chlorophyll formation.
Iron is an important element in maintaining good grass colour and required for chlorophyll synthesis, iron will also control moss.
Other elements are also required by turf in small quantities these include manganese, copper, zinc, iodine, sulphur, boron.
Calcium for cell wall formation.
Carbon, oxygen and hydrogen, supplied by air and water.
4) (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.
5) The obvious answer would be the standard `N.P.K.` required for `green`, `roots` and `fruit and flowers` respectively. However, we have (very) recently begun to understand that the requirements of sportsturf are vastly different from those of horticulture (from where we have historically derived much of our knowledge). One example is the reported effect of phosphates on `Poa annua` species populations. Another would be the effect of nitrogen application (particularly the timing of application) and it's relation to disease i.e. Fusarium patch and Anthracnose.
I believe that considering the major financial investments currently made in sporting venues, it has now been realised that more research needs to be done in this area before even we (as practising greenkeepers) begin to understand the requirements of the desired species. What must be remembered is that while we are often following standard horticultural techniques, this also encourages weeds and undesirable grasses. Our aim is for the ideal nutritional (also cultural and environmental) situation that is the perfect balance between encouraging our desirable species while discouraging our undesirable weed plants (and mosses/ algae/fungi). It must be remembered that competition is the first enemy of the sward.
Micronutrients are a difficult subject due to a lack of research at this time. Ferrous and magnesium additions are common, although the ferrous element is generally used to `check` moss growth. Seaweed applications are also currently popular.
The future, however, inevitably brings change as chemicals are being banned one by one. Our only alternative will, I feel, to fully understand the effects of (what we now call) trace elements and their effect on the beneficial microbes and fungi (buzz-word: Mycorrhiza) in the soil.
A further point is global warming. Can we discover how to overcome such problems as `Pythium Blight` before the effects become apparent here?
Ultimately, more research needs to be done if people require the sports surfaces they desire without resorting to chemical use.
6) 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
7) A balanced feeding program is critical in the health of the sward plant though the primary area of concentration should be the soil condition with bacterial and oxygen levels at the maximum achievable.
The grass plants feeding will depend solely on the environment in which it is grown and the purpose it is to be used for and the soil structure it is within.
Only with close monitoring can the correct levels of feeding be achieved, the grass plant requires numerous minerals to allow it to grow correctly, it must also be taken into account that as the grass is for sports purposes it will not complete its full growing cycle and this must be taken into account when planning a feeding programme.
Whilst the NPK is the most likely choice for feeding the benefits of mg and zinc should not be ignored.
In summing up the grass plants required feed is sugar, which the plant uses in all growth patterns.
The minerals we provide purely allow the plant to create them and as such do not have an absolute direct effect on growth. But fertilisers do assist in the creation of the sugars the plant requires.
Fertiliser is merely in my view is a vitamin boost for the plant.