Organic Matter Sampling
Everyone knows that the greens at St Andrews are great at this time of the year. They are smooth, have good pace (terrifying at times) and above all else, are firm to walk on.
Why is this so?
One of the reasons is that we keep our organic matter in the soil under control by frequent light dustings of sand. This dilutes the organic matter and provides a healthy environment for soil microorganisms to decompose the organic fraction further into useful nutrients, which will feed the turf for free!
Organic matter can be classed as decomposing leaf or root tissue from the grass plant. The area of most concern to turf managers is the top 4 inches of the rootzone. Excess organic matter can lead to soft surfaces that are unsmooth, potentially disease prone and water retentive. A deficiency of organic matter is also bad because the turf will become destabilised and will not cope with excess wear from foot traffic.
The Sports Turf Research Institute (STRI) visit us twice a year to assess the quality of the courses. They also analyse our soils for organic matter content, soil acidity, and nutrient levels. All we have to do is provide the samples.
Usually the courses will provide samples from 5 greens but every year one course is selected to get ‘the full monty’ in which all 18 greens are sampled. These same greens are tested each year to provide a historic account of fluctuations in organic matter etc.
This year it was the Jubilee course turn to receive the works…
The method for sampling starts with taking 9 cores from across the putting surface to a depth of 4 inches.
The cores are removed from the sampler and carefully transported to the next location. The picture below shows a core with the different layers of topdressing over the years. The top most layer has been achieved generally in the last few seasons, where we have intensified the whole topdressing process.
After all 9 cores are taken from the green, they are placed into a bag and mailed to the STRI for testing. Typical results are as follows:
So what does this graph mean?
Well, it shows that the level of organic matter has been decreasing over the last few years. This is positive proof that the topdressing regime is working. It also shows that 2 of the greens are perfectly within target! By using this data we can target individual greens with more sand or even less if required, with the final goal being consistency of all the surfaces.
Words by Graeme Taylor, Course Manager – New & Jubilee Courses