sand

A pound of nitrogen. That’s a substantial amount of N, right? Apply a pound of N in a single application and that’s going to create a lot of growth—way too much growth in most cases—and may lead to some thatch production.

I recommend annual soil testing of professionally-managed turfgrass grown on sand rootzones. For turf growing in soil, I don’t mind testing every two or three years. But sand rootzones usually aren’t very well buffered and important soil properties can change rapidly.

I’ve been thinking about this one a lot. It seems obvious that a sward supplied with more nitrogen fertilizer will tend to produce more organic material in the soil. It also seems obvious that a sward on which hollow-tine cultivation, or scarification, or sand topdressing, have been conducted, will need to receive more nitrogen in order to produce a surface compared with an adjacent sward that didn’t receive any of that work.

Chris Tritabaugh and I met to review the OM246 test results from samples collected in October 2021 at Hazeltine National Golf Club. We did this as a livestream episode of ATC Office Hours, which is available for watching or listening at your leisure.

You can use OM246 test results to learn how total organic matter compares to general recommendations; better yet, you can evaluate how maintenance practices, growth, weather, and decomposition are changing total organic matter at a single site; and then there is what I call the killer feature of this testing: you can make a precise and site-specific calculation of organic matter accumulation rate and sand topdressing requirement.

I’ve been working on an explanation of what OM246 testing is. The main point I wanted to make in part 1 is that the change in total organic matter between two measuring dates shows the result of topdressing, and growth, and weather, and microbial activity, and coring, and scarification, between those two dates.

This is an elaboration on, and an extension of, the calculations showing that hollow-tine cultivation, with removal of the cores, doesn’t reduce soil organic matter (OM) at all. That’s not an intuitive result, because OM has obviously been removed from the rootzone.

I used to think of hollow-tine cultivation, with cores removed, as one of the best ways to remove organic matter from the rootzone. Maybe even as an essential way to manage organic matter.

Perspective. It’s funny how that works. When I first read this research report in 2011, I skimmed over some parts, and cherry-picked what I was looking for — that 15 to 20% surface area removal was required every year in order to keep soil organic matter under control.

Today I explained the same calculation about sand topdressing for the third time, so I need to write a blog post on this topic. This is following the method of David Robinson, who says when you’ve written the same code 3 times, write a function; when you’ve given the same advice 3 times, write a blog post; and when you’ve done the blog post 3 times, write a book.