Noel Mackenzie: The role seeds and fertilisers play in helping turf

Seamus Rotherick
By Seamus Rotherick October 17, 2011 09:34

Probably the biggest area of turf supply is the finishing off of tee constructions and bunker refurbishments during the winter months. The turf will vary depending on the type of surface and the situation.

A few courses are blessed with really good local turf and can use supplies cut on site but most clubs do not enjoy this luxury. Even those with good local turf must be careful.

Turf for tees usually comprises good quality cultivars of dwarf ryegrasses, often in combination with smooth stalked meadow grass and fescue and bent grass species. Such turf can be used in a variety of situations but not for greens. Turf is still used on greens but rarely for patching up work, its use being restricted to re-surfacing activity. Usually, greens reconstructions would be completed in the autumn to allow a long grow in time before coming into play. The turf itself is nearly always a Chewings fescue; slender creeping red fescue and browntop bent species mix, but there are occasions where creeping bent might be used alone or another combination as determined by someone knowledgeable in the management of the different species. Choice may also be determined by the conditions within which the turf may be grown after it is introduced to a new site.

A key part of the purchasing process is the actual condition of the turf as much as the species mix. Harvesting stresses the turf considerably and weather conditions can hamper its condition as well. Reputable companies such as Inturf, Tillers, Rolawn and so on are well experienced in the growing and maintaining of good supplies for most of the year, though examining samples as well as the original species and cultivar seed mix information is time and effort well spent.

Fertiliser

As winter gives way to early spring and then spring proper, the focus shifts to seed and fertiliser treatments. Fertiliser is a key element of maintaining a good healthy sward through the year as cropping of clippings removes nutrients from the grass and this in turn can diminish the soil.

The modern trend for rootzone construction greens, which sole purpose in life seems to be to drain almost as fast as possible with scant regard for any other factors in maintaining turf, brings its own problems when it comes to fertiliser choice and maintaining a nutrient content within the turf. So, whether a soil or rootzone constructed green, the fertiliser choice is contingent on the construction, particularly, but not exclusively, the pH (acidity or alkalinity) of the soil, the CEC (cation exchange capacity) that determines the degree to which nutrient is held in the soil, rate of leaching in the face of irrigation or precipitation, organic matter contents and so on. Beyond the soil type there are factors such as the time of year, grass species currently growing and any future management objectives on that front (more bent grass perhaps), wear and other usage factors.

In fact, the list of possible situations is endless and so complex that totally accurate fertiliser programmes are impossible to apply to the ‘nth’ degree. Soil testing can be a useful guide but it can also be highly misleading and, without a very strong technical understanding, the results of these tests are often used to sell fertiliser by companies promoting high cost fertilisers when cheaper ones would do just as well, or sometimes even better. Foliar testing of leaf clippings can be useful too, but very often can also be too complex for good interpretation.

Fertiliser programmes should be simple but effective and allow sufficient scope for the greenkeeper to ‘flex’ the programme to make the most of prevailing environmental conditions. Through the year the greenkeeper should have a plan but the foresight and ability to manoeuvre treatments backward or forward as determined by growth and conditions. For example, the cold dry spring will have probably left a residue of unbroken down fertiliser this year so later fertiliser treatments may need to be reduced in order to allow for the breakdown and availability of this material to the grass at a later date. If this residue is not allowed for there may be a doubling up of nutrient from the first spring feeds that release their nutrient together thus creating a flush of lush and problematic growth.

Seed

Whereas fertiliser use will continue on and off on greens throughout the year, the use of seed is confined on most courses to just one or at best two occasions per year. Some clubs do not apply seed to greens at all. Let us consider this a little more closely.

Most clubs and good greenkeepers are trying to present a sward based on finer grasses that provide good putting surfaces, namely Fescue and bent grasses, either together or individually. Some courses are aiming to present creeping bent grass greens. In all these instances the annual meadow grass (Poa annua) is considered an undesirable presence, although in many situations it is acknowledged that this grass is actually a welcome undesirable because there wouldn’t be much else if it weren’t present!

On greens with any content of Poa it is a familiar sight to players and greenkeepers to see a white haze, mainly in May to early July, signifying the flowering of this grass species. Actually, the seeding is not restricted to this time and as many as six flowering episodes may be produced by a plant in a year. Each time the plant flowers up to 36 seed heads are produced and so it can be seen that the biological potential for seed production in a sward is phenomenal. Assuming a population of a few million plants the reproductive potential is colossal. On a golf green, are clubs content to throw a tiny amount of seed in the face of this potential and hope for the best?  For a club to have any hope of really working against a large Poa population it is surely sensible to throw more than one seed application at a green if the best is to be achieved.

We should, at this stage, pay note to the fact that managing species composition within turf is a long term process. Poa is encouraged by overwatering, lots of fertiliser and so on, and to work against it requires a good deal of perseverance and control in the other areas affecting the management of turf. In other words, a holistic approach to sward management is required. If the other factors relating to management are in place to achieve the right results, the benefits of an aggressive and correctly applied overseeding programme may be felt. Where fighting Poa is difficult is in high wear situations with limited drainage that are typical of many small golf greens (and tees). In such situations drainage or re-construction may be options to consider carefully but should not be rushed into.

It can be seen that the shift from winter into spring brings with it changing management inputs to the greens and tees.  Turf in winter needs to establish before use begins and the seed and fertiliser inputs are necessary both on new turf and on established turf surfaces. The correct choice for any of these inputs is contingent upon the situation that exists on the course and the agreed management objectives of the course and its management plans.

Seamus Rotherick
By Seamus Rotherick October 17, 2011 09:34
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