Technical
The world’s first dedicated golf topdresser introduced in 1961 by Turfco
How could this be achieved in an economical format, without tying up staff and vehicles for possibly days? The answer was the introduction of the spinning disc topdresser. Wide broadcasting of any topdressing was now achievable. This process has now progressed to provide accurate control of application rates, spreading widths, material density and the use of wet topdressing, if required. Now we are able to apply as and when required, heavy or light, wide or narrow. So, why are we doing this?
Topdressing is a small cog in the big machine of turf maintenance, but an important one nonetheless. No operation has a greater immediate effect on the surface and turf health than topdressing. It is used to create a surface that instils confidence in the golfer to roll in those nasty left to right downhill puts for birdies and keep them coming back for more.
The image of golf and the art of greenkeeping has changed through the years from the tees, fairways and greens carved out of coastal sand dunes to the pristine surfaces of today that we see on television every April!
Also, the pressure on the greenkeeper, tasked to produce such surfaces, has risen relentlessly; to provide a surface so good it’s near death, but without destroying a life’s work. That is why, from an agronomic point of view, we must be careful; plan our work to the best we can and, more crucially, time it.
Now, topdressing doesn’t start with a bumpy surface, it actually starts with our existing soil structure. What’s in our soil? How do we know what material we need? Remember, applying different materials means layering our profile, which results in a more compacted surface, a potential for more stress, limited root growth and development.
So choosing a compatible material is essential, whether it is a sand/soil mix or pure sand. Studying test reports from accredited
Drop spreaders provide highly consistent distribution of material due to the constant relationship between forward speed and the speed of the delivery belt
laboratories helps us understand required particle sizes and sufficient total pore space.
Now, in an ideal world, the ratio in soil would be 50% solids (sand, clay, silt, gravel), 25% air- filled pores and 25% water-filled pores. However, in some cases, like golf greens, 25% water filled pores may be a bit high, 12-15% may be desirable to give us a slightly drier surface. A slightly drier surface means better airflow, better plant/root growth, reduced risk of disease and a firmer faster surface among other advantages.
Generally, a freer draining substrate is one with a high sand content and low clay/silt content with a total pore space, which will be good and effective. To determine your existing soil profile, there are laboratories which can run tests and provide a detailed anaylsis. Low pore space soils, those that contain a higher percentage of clay/silt can sit wet for longer periods of time and these surfaces will be slow playing, soft, have a high risk of disease encroachment and poorer turf quality.
In this instance, modifying the soil through aeration and topdressing with sand will provide a significant benefit. The aeration procedure carried out would be hollow coring to remove material, leaving open holes into which sand can be introduced. The sand will help to create a drier surface by increasing the total pore space. The higher percentage of air and water movement can give us a higher percolation rate (the rate in which water drains through the profile).
It also means that we are encouraging better root/plant growth and development through exposure to more oxygen, and this will give us a better root structure which, in turn, provides a stronger plant.
Another critical improvement that both aeration and topdressing makes is to control thatch levels. Thatch is an accumulation of organic matter in the surface and too much of
Watch the How To ' Workshop - Top Dressing’ video here
The introduction of the spinning disk topdresser increased the efficiency of the application process enabling material to be spread over a wider area
it, anything from 3-5%, creates what is effectively a sponge, locking in moisture and nutrients and preventing them percolating down to the roots. The result is that the roots have to go looking for these elements, growing the wrong way and increasing that thatch level.
However, by removing organic matter and then topdressing, we are stimulating microbial activity. Microbial activity reflects the flux of carbon through biotic systems. Sounds a bit technical, but basically the microbial biomass (bacteria and fungi) decomposes the organic matter. With thatch levels reduced to around 1 or 2%, the organic matter left in the profile will hold the required moisture. A dry soil is inactive and will not stimulate microbial activity. If required, this microbial activity can be measured by trapping carbon dioxide (CO2) evolved from the soil in a laboratory test.
So again, with a reduction of thatch, we are producing a firmer, faster surface that recovers better, uses moisture and nutrients more effectively, and produces a healthier, stronger plant - kind of like us going to the gym!
And, like going to the gym, a little and often approach seems to work in the best way. Applications of topdressing material every two to four weeks has now proved to be the norm and to good effect. A little and often programme means a more sustainable, playable surface, all season long.
The aeration procedure carried out would be hollow coring to remove material, leaving open holes into which sand can be introduced
Modern topdressers are capable of spreading material in fine or heavy applications
A layer of thatch effectively acts as sponge locking in moisture and nutrients and preventing them percolating down to the roots
PC APRIL/MAY 2015 I 125
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