GvX and sand | Asian Turfgrass Center

A correspondent wrote with a question about the amounts of sand top dressing in relation to the GvX turf.

“I’m hoping you can point me in the direction of finding out something about sand input versus the GvX. I’ve listened to podcasts explaining measuring in depth but can’t recall hearing one on the recommendation of sand depending on your GvX?

The short answer is: I hope you won’t find anything on that, because I don’t think I’ve made any specific recommendations that tie a certain sand speed to a certain GvX.

I can elaborate on this answer based on three points that come to mind.

1. The reason I don’t link sand and GvX is because the GvX is the actual growth expressed in relation to the expected growth based on temperature (growth potential). What this means in practice is that the same GvX will have different clipping volume in different locations. For example, let’s take December 15 in London with an average temperature of 5°C and in Singapore with an average temperature of 27°C, with a GvX of 40 in both locations. To achieve a GvX of 40 at these temperatures, this corresponds to a daily shaving volume of 0.2 ml/m2² in London but 7 ml in Singapore. That is, because the GvX is adjusted based on GP, ​​the identical GvX of 40 in this example has about 35 times more actual clippings in Singapore than in London.

2. I can imagine that for each location the sand requirement is lower when the GvX is lower, and that the sand requirement is higher when the GvX is higher. But I’m not trying to link the amount of sand to the GvX.

3. I have suggested that 1mm of sand top dressing may be a reasonable amount for every 1 liter of mowing volume. That is, for every 1 liter of clippings per m2²add 1mm of sand for the time it takes to collect that much clippings. Doug Soldat tried this top dressing rate a research project at the University of Wisconsinand he has found that under the conditions of the experiment that amount of sand produced an average level of soil organic matter. One of the summary points in a project update is this: “While the different top dressing volumes [multiple methods of choosing a topdressing rate were tested] resulted in differences in soil organic matter (4.4% versus 6.1% after three years of divergent management), the differences in playing surface performance (speed, firmness, quality, density) were small within that range.”

Another way to get a site-specific estimate of sand top dressing is to use PACE Turf’s spreadsheets.

The way I really like to do this is by measuring the total organic matter at depth, the OM246, and calculating a sand quantity based on that.