Sand and nitrogen amounts: how I figure it out

A friend is in charge of a type of grass he hasn’t grown before. We went to look at the grass, and on the way to the golf course, he told me that someone had told him the grass didn’t need much sand topdressing. “Just mow and mow and mow, don’t topdress much,” he was told. Someone else told him the grass would need more nitrogen than other grasses.

“What do you think?” he asked me.

I told him that I much prefer to base the amount of N and sand we apply on site-specific measurements. I don’t think the best way to manage is from general advice. We can figure out the exact amount that will produce the result we are looking for by making two simple measurements.

For the N rate, adjust based on ClipVol

If the grass is producing more clippings than you want, reduce the N rate. If the grass is not producing as many clippings as you want, increase the N rate.

Isn’t this a simple approach, and more likely to produce the desired site-specific result, rather than “this grass needs about 3x more N than you usually use?”

For the sand topdressing, adjust based on OM246

If the total organic material at the surface of the green is higher than you want, increase the amount of sand applied. If the total organic material at the surface of the green is lower than you want, reduce the amount of sand applied.

Also, remember that every 1 mm of sand added will make an instantaneous reduction of about 5% in the 0–2 cm total organic material content. The exact reduction is actually a little more than that,¹ but for mental math purposes it’s easy to work with 1 mm of sand reducing 5%, or 2 mm of sand causing a 10% reduction in total organic material.

Isn’t this also a simple approach, and more likely to produce the desired site-specific results, rather than “Just mow and mow and mow?”