Sand topdressing and growth potential

A metric spreadsheet from PACE Turf uses growth potential to estimate topdressing rates

PACE Turf have prepared this spreadsheet that takes inputs of average temperatures and a maximum monthly topdressing rate, and gives outputs of estimated monthly and annual topdressing sand amounts.

It is a metric version of this:

“To get a rough idea of how much sand to apply over the course of the year, we have developed a simple spreadsheet that uses growth potential (GP) as a guide, and a maximum sand application of 150 lbs dry sand/1000 ft2 per month at maximum turf growth.”

The units on the sheet are kg/100 m2.

Now for a little aside about units I find convenient. I like to use depth (mm) when working with (or thinking of) topdressing amounts. One mm of sand spread over 1 m2 has a volume of 1,000 cm3 (1 L) and weighs about 1.5 kg. It is easy to work in units of depth and convert to volume or mass as necessary. One mm of depth is equal to a liter of volume and with sand that will weigh 1.5 kg. Thus, one can work out some of the relationships without having to think too hard or turn to a calculator.

The default maximum topdressing amount per month on the spreadsheet is 75 kg/100 m2. That’s a depth of 0.5 mm. If the GP were high every month, and the grass grew accordingly, then that would predict an annual topdressing amount of about 6 mm. That, by the way, is also the quantity of sand identified by Schmid et al. as the amount applied to consistently manage soil organic matter in the top 7.5 cm at 3.3% or below.

And that 6 mm would weigh 9 kg/m2.

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