Grass fertiliser/topdressing

Don't just repeat fertiliser types and procedures used last year, consider the current climate.

The weather has been a bit odd recently. Whether you put it down to climate change or not, it does seem likely that the unpredictability and the extremes will continue. If you were thinking of applying the same type of fertiliser as last year, you’d be wise to think again.
Repeating last year’s fertiliser programme will benefit the distribution chain, but is not necessarily what your grass wants. You need to know how much nutrient was used by that spell of growth just before Christmas and how much was flushed out during the winter. The starting point should be an analysis of the nutrient status and identification of any specific needs.
It is important to recognise that even where a single soil type is present, considerable nutrient variation can occur across one sports facility. Turf that is in shade is likely to have a different nutrient requirement from that in full sun. The same may apply to turf on slopes or areas of heavy traffic. The type of grass will affect nutrient requirements so the greens, tees and fairways of a golf course should be considered separately.

Aim of the game
As the grass wakes up in spring, the aim is to help it into growth and then maintain steady, healthy growth throughout the season. That does not mean throwing nitrogen at it. A few years ago it was commonplace to give turf an early season wake-up call with an 18-0-0 straight fertiliser — but times are changing.
Commercial development manager Clive Williams at Vitax, a fertiliser manufacturer in Coalville, Leicestershire, says: “If you apply a mineral fertiliser it will simply make the grass grow. Straight nitrogen fertilisers, such as 18-0-0, were best sellers at one time, but the trend is back to fertilisers with a bit of potash in them as well as nitrogen.”
Williams believes that turf managers need to think carefully before applying straight mineral fertilisers as they leach quickly and promote the production of soft, lush growth. Avoiding leaching is important. Recently declared nitrate-sensitive areas have increased from five per cent to 55 per cent of the land surface. Government and environmental bodies are muttering about nitrate pollution. The wise use of fertiliser could delay possible restrictions or taxes on fertiliser use in the future.
Williams says: “We are looking at fertilisers that are retained in the soil in an ammoniacal rather than nitrate form because the ions will keep it in the soil. The plant may have to work harder to get the goodness out of it, but the result tends to be sturdier, shorter jointed growth instead of elongating the blade.”
Many turf managers have moved away from high nitrogen fertilisers in the early spring because of the vagaries of the weather. The risk of a late cold snap in spring means that soft, lush growth should be avoided early in the season.
“A lot of managers are using low nitrogen levels with more potash and perhaps a smidgen of iron to give steady growth and improve turf,” says Williams. “Turf professionals would also be wise to encourage root growth so the grass is better able to withstand droughts.”
The usual rules concerning formulation and granule size apply. The risk of fertiliser granules being carried from the site on the soles of shoes or the bottom of machinery increases when conditions are wet. Where the height of cut is very low, such as for greens and cricket squares, granules can also be picked up by mowers and deposited in the clippings box before the fertiliser has had a chance to break down and do its job.
Mini-granular and powdered fertilisers or liquid feeds are appropriate for fine turf situations. Liquid feeds are useful for supplementary feeding as they provide plant food that is readily available and used immediately, so response is quick but not necessarily lingering.
Whatever you choose, check the nutrient analysis in combination with the application rates. Make sure the product is uniform and consistent throughout as this will affect its spreadability and, ultimately, will show up in the colour and growth patterns of the sward.
If you are looking for topdressings, an important factor to consider is the purpose. Do you want a level surface, to increase the organic content or return nutrients to the soil? The topdressing needs to be compatible with the rootzone mix and should have the required characteristics in terms of pH, particle size, uniformity and sterilisation.

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