Technical
By breaking down the thatch within the soil profile, locked up nitrogen started to be released, and the greens would start to self feed. This self feeding would mean a reduction in nitrogen inputs, and a small cost saving could be made
and allow air into the base of the turf. Apart from helping to reduce thatch accumulations, verticutting was having a beneficial impact on the smoothness of the putting surface by thinning any tufted growth.
With fertiliser now being applied in a more controlled manner, and verticutting helping smooth the surfaces, the greens, in the short term, started to perform much better. These short term improvements to the putting surfaces reassured the membership that the management team could produce better surfaces. This was going to be important, especially for the times when disruption was inevitable. The underlying problems, however, still remained and, if the greens were subject to any sustained rainfall, the surfaces would deteriorate once more.
Starting to dilute the thatch
green at Sandwell Park in 2009 at the start of the thatch reduction programme
A soft, uneven surface at the side of a Stop Creating Thatch
The first part of any thatch reduction programme must be to slow the volume of organic matter being produced. One of the main contributors to thatch is shoot and stem growth. To ensure that stem growth was not excessive, nitrogen inputs were evaluated and it was decided to deliver nutrients in a much more controlled manner. This was done by spoon feeding the greens with liquid fertilisers and seaweed, rather than applying nitrogen rich granular fertiliser. Applying nitrogen rich granular fertiliser would only create growth spikes, resulting in excessive shoot growth and thus exacerbating the problem.
To further control stem and shoot growth in this dense, Poa dominant sward, regular verticutting was employed to remove these lignin rich parts of the plant. It is these parts of the plant that die and contribute significantly to thatch accumulations. Along with the removal of the woody parts of the plant, the verticutting would remove debris
Topdressing is a key part of any thatch control and reduction programme. If we were going to reduce the amount of thatch with minimal disruption to play, then regular light topdressings were going to be an integral part of the programme. Before I arrived at Sandwell, the club had been advised to switch to a straight sand dressing, compatible to the dressing mix they were using previously. The move to straight sand was one that I had no intention of reversing, as the moist sand was going to be considerably more cost effective than kiln dried mixed topdressing that had been used. I understand the fors and againsts of using straight sand. However, significant thatch levels require significant amounts of dressing and, in this case, the cost implications were too great to ignore.
With high thatch levels like the ones at Sandwell, it was estimated 150+ tonnes a year would have to be applied. I have heard many people talk about burying thatch to levels that can’t be reached by hollow tining or deep scarifying by applying high volumes of dressing. However, this is something that I have never witnessed and, by carrying out the loss on ignition tests in measured zones within the profile, it could be shown that this was not happening at Sandwell Park. There are obvious cost implications of applying these amounts of topdressing. However, topdressing is one of the only materials applied to a golf green that has residual value in the form of aiding drainage.
Aeration
Aeration was going to be another key component in the thatch reduction programme. By getting air into the thatch, soil life would be increased and this, in turn, would help break the thatch down in situ. By breaking down the thatch within the soil profile, locked up nitrogen started to be released, and the greens would start to self feed. This self feeding would mean a reduction in nitrogen inputs, and a small cost saving could be made.
Initially, solid tining was carried out in the summer and slitting in the winter. This type of aeration also started to allow the migration of topdressing into the thatch layer and this, in turn, would further accelerate the decomposition of the thatch. It was clear from the start that not all the thatch was going to be broken down in situ, especially in the densest layer from the surface to 20mm. Because of this, there was going to be a need for thatch removal. I often advise thatch removal on greens with higher than 10% organic matter within one zone of the soil profile. Greens with excessively high organic matter content, i.e. higher than 10%, often have poor soil life and sit wet for long periods. Therefore, even when aeration is carried out, such as slitting and tining, the soil life populations remain low due to the hostile environment. So, it was decided to remove the thatch by deep scarification as this was the most efficient way of removing it, with 2mm tines at 25mm spacings hitting approximately 9% of the surface area, compared to approximately 4% of the surface with 15mm hollow tines at 50mm centres. Once the scarifying debris was removed, the greens were dressed with 40 tonnes of sand. On the more free draining greens this process worked well. However, after heavy rainfall, it was clear that the wetter greens had actually become more unstable and, in places, the turf started to split. Fortunately, this work was carried out in late August so, once the greens had a spell of dry weather, they increased in firmness and repaired well. However, this temporary softening of the surface was a concern and I felt uneasy that the deep scarifying slits were not all the way through the thatch layer. Instead, water was discharging into an organic rich rootzone. Therefore, it was decided that the best form
PC AUGUST/SEPTEMBER 2014 I 127
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