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Fertilizer 2015: More reductions in quantity, not quality

Total fertilizer applied per year
For the past few years I have made big reductions in fertlizer use on my golf course. How? I started using the MLSN guidelines and based my fertilizer applications more or less on the temperature based growth potential model. If there is enough of an element in the soil, I don't apply it. Plain and simple and it works. Where I used to have a fertilizer program, I now apply it as needed based on the weather and conditions I am trying to produce.

What are those conditions? Good healthy grass that grows as slow as possible while putting up with the traffic and other stresses that it is subjected to.

A lot of focus is always on pesticide use but the misuse of fertilizer could probably be said to contribute more to pollution and adverse health effects than pesticides so therefore it is important to me to only apply the amount that is absolutely needed. No more.

This year we had a warmer than normal summer. The growth potential hovered at near 100% for 4 months where it normally only does so for 2 months. I did, however, adjust my growth potential formula for bentgrass over poa. Essentially I made the ideal temperature warmer (20c) and the ideal amount of nitrogen per month down (3.5g/m2/month). This was from an ideal temp of 18C and ideal nitrogen amount of 4g/m2/month. So even despite the prolonged summer and very stressful conditions, I still was able to reduce my fertilizer use on greens by almost 40% by weight.

total Kg fertilizer applied to course.
Why did I make these changes? Well I had heard of others with similar turf species going that low, so I thought that if they could do it why couldn't I? I made a few adjustments to my GP formula and voila. I first talked about this on my post about aeration.

Surely such a huge reduction would have a noticeable impact, right? Well if there was one I couldn't figure out what it was. Maybe the only difference has been less thatch on my fairways, smoother firmer greens, less disease, less water use, and more rocks poking through the thatch! These are all just casual observations but seriously, things have never been better.

Now was I using more expensive products to achieve these reductions? You tell me.



Yeah, that a reductions of 40% as well. Interesting. You mean you don't have to spend more to apply less?

So what exactly did I apply this year?
Fertilizer added in 2015
Now you might be thinking, yeah, he just used more concentrated fertilizer to get low numbers. I have been using these fertilizer sources starting in 2009. No, I simply applied 40% less (or more than that) of each individual nutrient. 
Nutrients applied in 2014
Greens: 80% of growth potential rates at 20C and 3.5g N/m2/month, MLSN Guidelines, applied weekly during growing season

Tees: 75% of what is applied on greens as the clippings are returned. MLSN Guidelines, applied monthly

Fairways: Not much. applied every 3 weeks through growing season, monthly in shoulder season

The source of nutrients that I used this year are, urea, ammonium sulfate, potassium sulfate, monopotassium phosphate, iron sulfate, potassium phosphite, monoammonium phosphite.

I haven't applied a granular in years but I expect to have to next year on tees to supply some calcium and as a pH adjustment. I am only applying N and S to fairways as a big weed experiment inspired by the work done at the Park Grass Experiment at Rothamsted.

Other than that there's not much to report. Despite the most challenging drought conditions I have ever seen, we managed just fine and the course was the best it has ever been.
Greens were nice


so were the tees

surprise, even the fairways were good, and have less weeds too ;)


Fertilizer isn't that hard, don't over-complicate it.





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