Is two tenths of a pound of nitrogen a lot, or a little?

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. Certainly the application of that much N is going to require some grooming and verticutting and sand topdressing in order to keep the turf from getting too puffy.

By a pound of nitrogen, I mean 1 pound of N applied per 1000 ft2. That is equivalent to 5 g N/m2, or 50 kg N/ha. Two-tenths of a pound of nitrogen per 1000 ft2 is 1 g/m2 or 10 kg/ha.

But two tenths of a pound—1 gram—that much N doesn’t really register, does it? The average amount of N applied to putting greens in the United States, across all regions of the country, was 3.1 lb/1000 ft2/yr based on a 2021 survey.1 That’s about 16 g/m2. What if this was 2.9 lb (15 g), or 3.3 lb (17 g)? That doesn’t seem like such a big difference, that little bit of N, that change of $\frac{2}{10}$ of a pound.

We would all agree that a difference of 1 pound would be meaningful. The thing is, if you change the N by $\frac{2}{10}$ of a pound per year, then after five years, it’s a pound.

Adding even a little more N than needed will lead to more growth, and that growth produces aboveground and belowground plant material. The cumulative effect of small excesses of N must be a reason for some thatch production.
Adding even a little more N than needed will lead to more growth, and that growth produces aboveground and belowground plant material. The cumulative effect of small excesses of N must be a reason for some thatch production.

From a pound of N, if that all got taken up with 100% efficiency by creeping bentgrass, I’d expect that much N to produce a clipping volume of about 2.1 L/m2. For reference, that’s about an entire growing season’s worth of above ground growth in a place like Chicago.

What I’m getting at is that every little bit of N is meaningful, and a little N can go a long way, and what seems like a little bit of N can over the long term become an amount of N that would contribute to thatch buildup.

See what if it was never there for more discussion of this topic.

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