New Challenges In Turf Management
Turf management is evolving. As I’ve discussed before, the method of ‘see problem – spray chemical – fix problem’ are coming to an end. Fungicides cannot be used effectively on a curative basis and nearly all the amenity-approved insecticides are banned.
Looking at the bigger picture of what your actions do to your turf is more important than ever. Sometimes to prepare a surface for an event we carry out operations or apply products that in the short-term give us the surface we need. But as the old saying goes, every action has a consequence. What are your short-term solutions doing to your turf in the long-term?
We see this in all aspects of life. How often will a government cut taxes to win votes? Short-term they may stay in power, but long-term the economy suffers. They are keeping the customer (voter) happy, just as we may double-cut a surface and spray nitrogen + iron to present a beautiful green, striped surface to keep customers happy. We’ve all done it, but we must remember we can’t dip into the chemsafe quite as easily to save our bacon anymore!
Key questions to ask are what are the long-term impacts of verticutting, scarifying, raking, aeration, lower mowing heights & double cutting, rolling, etc. On top-spec football pitches there is less need to worry about these practices as the sward is removed every year and replaced with a new one. For lower spec sports pitches and other sports surfaces, you should consider how these operations affect sward composition, rooting, soil biology, thatch accumulation, surface compaction, etc.
Do you know what is in the products you apply? What will these do to your soil or turf in the long-term if you carry on applying them?
I’ll give you a few examples of what I mean which you may or may not have considered:
Applying Iron (Fe)
Benefits: Greens up turf, reduced moss ingression, reduced disease spread.
Potential consequences: Build-up of iron in soils from granular fertilisers can lead to black layer, reduced rooting and reduced soil microbial activity (increased thatch accumulation). Iron pans are known to build up at sand/gravel interfaces in sand-based pitches/greens and reduce infiltration rates.
Applying Sulphur (S)
Benefits: Sulphur is often ‘hidden’ in fertilisers. Ammonium sulphate is a common N source, potassium sulphate a common K source and sulphur-coated urea is a common way to produce a slow release fertiliser. Sulphur is needed for nitrogen assimilation by the plant so can improve turf appearance. It acidifies soil which can reduce worm casting.
Potential consequences: Long-term use of high-S fertilisers will reduce soil pH, meaning less N availability (you need to apply more N for the same effect – if nitrogen sources with high sulphur levels are used the pH then goes lower and you get into a vicious circle). It has a role in the creation of black layer when used alongside Fe. High S and low pH reduce soil microbial activity (more thatch build up, less disease resistance, poor nutrient cycling). Lower soil pH also increases iron mobility in the soil, leading to a greater chance of iron pans.
Verticutting
Benefits: A thinner, more refined surface that improves ball roll and removes yellowing leaves within the sward.
Potential consequences: On golf greens and sports pitches, over-use of verticutting can create an environment more favourable to Poa annua than perennial grasses. Verticutting when soil moisture is low or air temperatures are high can knock plant health, leading to anthracnose or other stress-related conditions such as parasitic nematode stress symptoms.
Scarifying
Benefits: Reduced thatch build-up, removal of ‘too thick’ grass coverage, increased air around plants.
Potential consequences: Pitches can become too thin and lack coverage if poor growing weather follows, surface levels disrupted, can open surface and allow Poa annua ingression.
Applying Garlic
Benefits: Known to reduce populations of plant-parasitic nematodes and leatherjacket grubs.
Potential consequences: It’s not only plant-parasitic nematodes that are killed in the soil, beneficial nematodes and other beneficial soil microbial life are also affected. Garlic is not approved for leatherjackets, so this is an illegal practice. Garlic is known to severely reduce the extremely beneficial mycorrhizal association with grasses which has long-term negative effects on plant health.
Lowering Mowing Height
Benefits: Increased ball roll on all sports, smoother ball roll during certain times of year for golf/bowling greens.
Potential consequences: Creates an environment more favourable to Poa annua. Less leaf blade size = less carbon returned to benefit soil microbes. Less leaf generally means less root. Smaller plants generally more disease prone.
Sand Top Dressing
Benefits: Creates a firm, level surface. Increased infiltration rates to keep the surface dry. Increased ball roll speed across the surface.
Potential consequences: Very expensive over large areas and sand availability will soon be limited. Creation of a high sand/low organic rootzone reduces natural thatch degradation and low nutrient/water retention requiring high maintenance levels of irrigation, fertilisation, coring, scarifying and more sand.
Applying Nitrogen
Benefits: Vital for grass growth, gives good appearance and recovery from wear
Potential consequences: Too much N availability when you don’t need it produces lush, weaker growth that is vulnerable to disease. Hidden N in products is becoming more common. How much N is in your seaweeds/biostimulants? ‘Soil oxygenators’ or ‘aeration in a bottle’ often can have high percentages of nitrates in them that force growth you may not be expecting.
Seaweed
Benefits: Stress reduction, increased microbial activity, increased root and shoot growth at lower nitrogen inputs.
Potential consequences: Over-applying seaweed can actually reduce root growth. Although it will still benefit soil microbiology, too much seaweed has been shown to reduce root mass in certain situations – more does not always mean better!
With everything you do, there is too little, just the right amount, and too much! I often talk about the way plants and people react in similar ways to inputs. If humans eat or drink too little we become weak and unable to fight off colds and illnesses. If we eat or drink too much we get overweight or start to suffer with diabetes or high blood pressure, etc. Plants are not that different – give them too little and they’ll be weak, give them too much and they’ll be weakened too. Making sure they have just enough of everything is key.
It can take experience and experimentation to work out what the ‘Goldilocks’ levels are for your site for individual products and operations. I commonly find that turf managers are unaware of some of the ingredients in the products they use and often the tendency is to apply too much. Every issue or situation seems to warrant an aeration or raking or applying a cocktail of products. Sometimes the best thing to do is nothing. Try to understand what you’re doing to your turf and think about the longer-term consequences of that action.
This is obviously not an exhaustive list and you may well feel that the benefits outweigh the drawbacks of some of the operations or products here. That’s fine, it’s your turf, just be aware of what those drawbacks are.
Geoff Fenn BSc (Hons) – gfenn@advancegrass.com
