The Winter's Tale

There are more surprising photos from Doug Soldat this week. Where potassium fertilizer was applied, there is more snow mold. Where potassium was not applied, there is less snow mold.

This photo, starting in the top right plot with the lowest amount of snow mold, and going clockwise, is:

  • top right, no K for six years
  • bottom right, no K for six years but high K added from August to October 2016
  • bottom left, high K for six years
  • top left, high K for six years but no K after August 2016.

It's not so surprising, actually.

Doug has been observing these results for some years now. See, for example:

This is one more post the financial controllers might not want to see

When I received an e-mail from Tom Sedlmeier a couple months ago, I was reminded of this update on the Sports Turf Solutions Facebook page in 2012:

I just read a blog that puts every Turf Managers [sic] budget under scrutiny. Lets [sic] hope the financial controllers at each club dont [sic] read it.

This post is along the same lines, so financial controllers should probably stop reading right here. Although surprisingly in the note from Tom, he did mention that the savings he has made were "greatly appreciated by the management."

Here's Tom, with emphasis mine:

Hi Micah, We haven't had any contact yet, so I'd like to introduce myself a bit first. I’m the Superintendent here at Mazagan Beach & Golf Resort in Morocco, working for Troon ... I was starting a lot of research in the internet last April when I first read about MLSN. I was very fascinated about the approach and modified immediately my plans for this year. And what should I say… I had a great summer this year with less growth, less clippings, less mowing, less fertilizer, less diseases and a beautiful looking golf course in great condition ... So all in all I had savings of about $150k this year, what was greatly appreciated by the management ;-). So I’m convinced by MLSN and GP…

I love to hear about those kind of excellent results, and I'm glad Tom was able to achieve them and then share them. As I mentioned in the recent Campus del Césped webinar, the MLSN approach is designed first to ensure the grass is supplied with 100% of what the grass can use. And as an accidental result, one can end up applying less fertilizers if one actually works through the calculations to find out how much the grass really needs.

You can find out more about MLSN and GP (temperature-based growth potential) during seminars at the upcoming Golf Industry Show and at The Canadian Golf Course Management Conference. Or check out the MLSN Turf page, or this blog's fertilizer topic.

Heck, you might even share this with your financial controller.


Preventing nutrient deficiencies


The recording of my webinar on preventing nutrient deficiencies is now available in the videoteca section of the Campus del Césped website.

Or watch the English version right here.

This was fun. I hope you'll read the handout too. It is only 4 pages, with lots of white space, and gives a brief overview of this important topic. If you are still interested, then watch the video of the webinar at your leisure, and watch or download the slides too.

Links in English

Links in Spanish

This is a lot to fit into an hour

But I am going to try. I've got four things I want to explain in this upcoming webinar, and I have made some interesting calculations. Can calculations be provocative? Maybe these ones are provocative and interesting.

The Campus del Césped webinar is on 12 January at 17:00 Central European Time. You can register here.

Here is the 4 page pdf handout, in English.


These are the slides in English.

These are the slides in Spanish.

If you are are joining this webinar, you will find it useful to review the slides and handout prior to the event.

Why I don't worry about micronutrients

This is nothing new. We've been discussing this for a long time. But these charts are new. I am leading a webinar on January 12 and in my preparations for that I made these charts.

I wanted to explain why I don't worry about micronutrients.

I'm going to explain this in words first, and show the charts at the very end. There are two main reasons why I don't worry about micronutrients.

First, the quantity of micronutrients used by the grass, when compared to the amounts of N, K, P, Ca, Mg, and S, is indistinguishable from zero. The grass uses micronutrients in such tiny amounts that it seems the grass can surely get such tiny amounts from the soil.

Second, and this is connected to the first reason, the quantity of micronutrients used by the grass is almost nothing. So there is no excuse for having a deficiency of any micronutrient, because even to apply two or three times as much micronutrients as the grass can use will cost essentially nothing.

Take those two reasons together, and you can't lose. You will probably never have a micronutrient deficiency, And you can spend almost nothing and be sure to prevent one.  Sounds easy to me. Which is why I don't worry about it.

Here are three charts to demonstrate what I mean.

First, this is the concentration of elements in turfgrass leaves. You'll notice that the concentration of micronutrients in leaves is indistinguishable from 0.


That's reassuring. The soil can probably supply almost all that the grass can use. But what if the soil can't supply that much?

No problem! The amount the grass uses is so small, it costs almost nothing to supply it.

If you have a 50,000 dollar fertilizer budget, and if all the elements cost the same, you would spend less than 60 dollars for each of the micronutrients. So if the amount used by the grass is so low, it seems easy to apply that much, and to afford that much, as fertilizer.


Of course not everyone has a 50,000 dollar fertilizer budget. What if your fertilizer budget is 700 dollars? Well, the grass won't distinguish between budgets, but it will still use nutrients in the same proportions. In this case, for a 700 dollar fertilizer budget, each of the micronutrients comes in at less than $1.

I hope this makes it clear why I don't worry much about micronutrients. You will probably not be deficient. But if you are worried about it, apply them. It will cost almost nothing.


Of course, if you are spending a lot of money on micronutrients, or are supplying a lot more than the grass can use, it would be prudent to ask yourself "What am I trying to do?"

"Maybe those that soil test are just more likely to fertilize in general?"

Ryan Goss made a good point in the discussion about how much fertilizer is applied on golf courses. Original blog post here.

There are two basic scenarios.

The first scenario is no soil testing, in which it makes sense to apply the same amount of fertilizer, F, as the grass can use, G. One doesn't know how much is in the soil, one can assume the soil will supply nothing, and as an equation this can be represented as F = G. Maybe add just a little more to be sure. Call it F = G + 10%. I'd think of this as a hydroponic situation, where the soil can supply nothing.

The second scenario is with soil testing. In this case, the amount of fertilizer to apply should be the amount that the grass will use that cannot be supplied by the soil, S. Any amount that is supplied from the soil is not required as fertilizer. In this scenario using soil testing to find what the soil can supply, the amount to apply as fertilizer becomes F = G - S. Maybe add just a little more to be sure. Call it F = G - S + 10%. If the soil can supply nothing, then S is 0 and the equation simplifies to the "hydroponic" situation described in the first scenario.

With these simple equations, it is apparent that the amount of fertilizer to apply, represented as the value F, will always be lower in the second scenario, with soil testing.

Ryan is right that those who soil test are probably more likely to fertilize in general. But there is something interesting if we look at the data in Table 7 from Gelernter et al. (2016). Phosphorus and potassium are often recommended based on soil tests, but turfgrass nitrogen rates are not based on soil tests. Therefore, I'm going to use the amount of N applied as a baseline estimate of how much more likely soil testers are to fertilize than non-testers.

I use the log percentage (L%) to show the relative changes. More about log percentage at the end.


I took the average L% increase across all areas of the golf course for each nutrient. A typical 18 hole golf course that soil tests will have an 18 L% increase in nitrogen rate compared to a typical golf course that doesn't soil test. Because nitrogen is not based on soil tests, I'll pick that number and say that the overall increase in fertilizer from those who soil test is likely to be 18 L% more than those who don't soil test, just based on what Ryan pointed out.

Then I move to phosphorus and potassium and compare them to the 18 L%. Phosphorus and potassium recommendations are based on soil tests, so if they increase by about 18 L% too, then we can't say soil tests have anything to do with it. Phosphorus fertilizer (shown as P2O5) was variable. The average was a 19 L% increase when soil testing, but there was a wide uncertainty interval around that estimate.

Potassium had an average increase of 39 L%. Even if the typical golf course that soil tests is already likely to apply 18 L% more fertilizer in general, that baseline increase does not explain the 39 L% increase in potassium fertilizer.

Why log percentage (L%)? This is described in Törnqvist et al. (1985) as "the only symmetric, additive, and normed indicator of relative change."

I didn't want to compare the absolute amounts of N, P, and K applied, because it is normal that one will apply more N than K, and more K than P. Saying the soil testing sites used half a pound more N (it was 0.4875 lbs more, to be exact) than the sites that didn't soil test is fine. Then I can also say that the soil testing sites used 0.16 pounds more P2O5 than did the sites that didn't soil test. Both those statements are correct. But that's not exactly what I want to compare. I don't want the absolute difference. I can't compare the half pound of N to the 0.16 pound of P. What I'm interested in is the relative change.

I could use the usual percentage, but that has problems too. The sites that soil tested used 3 lbs of N on average. 3/2.5 = 1.2. 3 is 120% more than 2.5. A 20% increase. So is that also a 20% decrease? 20% of 3 is 0.6. That's not symmetric. And 2.5/3 = 0.833. So is it a 17% decrease then? Or a 17% increase? It is confusing.

The log percentage solves this. ln(3/2.5) = 0.182. An 18.2 L% increase. ln(2.5/3) = -0.182. An 18.2 L% decrease. Very convenient.

The soil test numbers are almost double MLSN standards and I'm still getting recommendations to apply more

That arrived in my inbox recently, plus a few questions about calculating K requirements using the MLSN guidelines, and whether if there are minimum levels, are there optimum levels too? Here's how I answered.

It sounds like you are on the right track. Here's a few general remarks based on what you described/asked:

If the lowest K on that course's greens is 57 ppm, you are great. You are mostly Poa on those greens, right? The grass will use about twice as much N as it does K. Therefore, my suggestion is to apply half as much K as you do N, and that should keep the soil at about that level well above MLSN. Check a year later and see if the trend is going up or down. If going up, you can cut the fertilizer, and if going down you might increase it. What you are basically doing is applying 100% of what the grass is using plus you are keeping a nice reserve in the soil. That is a safe way to do it and it is not gratuitous overapplication.

For the other courses, it makes sense to let the numbers get a little closer to the MLSN minimum. I would make the calculation based on the soil test and the expected N application rate. The 22 ppm change in soil concentration is correct for a pound, if you are thinking of a 6 inch deep rootzone. For putting greens -- actually for most mowed turf in general -- I think of the rootzone as being 4 inches. In that case you can expect a pound of application per 1000 ft2 to increase the soil by 33 ppm. You can expect the harvest of a pound per 1000 by the grass to reduce the soil by 33 ppm.

If you apply 4 pounds N, expect the grass to harvest about 2 pounds K (50% K use compared to N). MLSN at 37 ppm is about 1 pound of K. That's always going to be there in reserve; we don't want the soil to drop below that. If you have a soil test at 45 ppm, then the way to calculate a fertilizer requirement is like this.

Amount needed is amount to keep in reserve (the MLSN minimum) plus the amount the grass will use minus the amount actually present. I'm going to say you calculate this for a 4 inch rootzone depth and you will apply 4 pounds of N.

That is 2 lbs of K use + about 1 lb K needed as the MLSN minimum - (45/37 = 1.2 lb in the soil now). That is 3 - 1.2 = 1.8 pounds of K required to keep the grass from dropping below the MLSN guideline. I suggest dividing that 1.8 pounds (your number is going to be different, I am just showing how I make the calculation) into as many apps as possible and then applying it through the season. Or, if you are applying 4 pounds N, then you have a 4 to 1.8 ratio of N to K, and just apply close to that ratio at every application.

It can be simpler than that, but that is the detailed work through of the calculations. The really simple way is if the soil is less than 50 ppm, apply N and K in a 1:1 ratio. That is bound to make the soil K go up, so you will be sure to be staying above MLSN. If the soil is in the 50 to 75 ppm range, apply 2:1, and that should keep the soil at a similar level. When the soil is above 75 ppm, so long as you aren't applying a ton of N, you probably can get by with little or no K.

I prefer to make the exact calculation. And then check the grass response to the fertilizer and adjust inputs accordingly.

Oh, is there an optimum? I don't think there is. I think there are problems if you get too low with any element, but once you move from "too low" to "enough", then all the benefits from that element have happened. The MLSN approach is designed to prevent you from getting "too low" and to make sure you are always in the "enough" range. Once there is enough, the problems are expected to be from traffic, or dry spots, or shade, or whatever. The idea with MLSN is to provide a framework to put every element in the "enough" range and then you can focus your limited time and energy on the other things that might be affecting turfgrass performance.

This is probably superfluous, but ...

I feel like there is something not everyone understands about the quantity of fertilizer recommended by the MLSN guidelines. A question came up in my Twitter feed this morning, and I wasn't sure if it was about implementing MLSN, or not. It certainly seems to be a common concern, something along the lines of "how can I be sure that I'm supplying all the nutrients the grass needs?"

No matter what kind of grass you are growing, or in what climate, the calculation of nutrient requirement using the MLSN guidelines has already accounted for 100% of the nutrients that the grass can use.



The calculation of how much of each nutrient to apply, based on the MLSN guideline, is basically the same as the Precision Fertilisation method of STERF. The one difference is that the MLSN approach considers the quantity of nutrients in the soil.


If the nutrient content in the soil is a lot more than the grass can use, then none of that nutrient will be recommended as fertilizer. If you are not familiar with the calculation, see this presentation on the MLSN guidelines and specifically look at the equations on slides 4 and 5.

The STERF approach is to apply 100% of what the grass uses, no matter what the soil content is. That is sure to work well. The MLSN approach is to make sure the grass is supplied with 100% of what it can use plus keeping a buffer of nutrients in the soil that will never be touched. That buffer is the MLSN guideline level. Because MLSN considers the nutrients in the soil, when the soil nutrients are more than the amount the grass can use, while still keeping enough in reserve to stay above the MLSN guideline, none of that element will be recommended as fertilizer.

Either way, the grass is supplied with more than 100% of the nutrient it can use.

For more about this, see:

A little aside here -- I receive way more inquiries about MLSN and turf management in general than I can answer in any kind of detail, or at all. I appreciate all the interest and questions, and thanks to all these questions I have continuously expanding GNU Emacs files entitled blog_posts.org, data_analyses.org, and writing.org. If I haven't answered your question, it's in one of those files for future attention.

A couple new things, and a reminder of an old one

When I saw that Brad Revill had started a blog, I was intrigued, because there are not many blogs written by turf managers in the tropics. I was even more intrigued when I saw that the title of his very first post was The start of something new -- MLSN!!. He wrote:

For years I have been following the recommendations from soil testing laboratories trying to create the "ideal soil" with the correct ratios of nutrients. After each soil test I would follow the recommendations, most of the time adding more and more calcium. After each test my ppm values would increase along with the "target" ppm values which kept getting higher and higher until it seemed I would never reach it. I grew frustrated with the recommendations and after reading article after article and research papers online, I came across the MLSN guidelines produced by Pace Turf and Dr. Micah Woods.

That's a new blog that I expect will be quite interesting to read.

Now for my annual reminder of an excellent resource, the Golf course management blogging world site. This site aggregates blogs from around the world and shows the most recent updates at the top.


The site administrators sometimes make manual updates to confirm the feeds are correct and the code is updated. I'm hoping they will do a refresh on the site again this winter to make sure all the feeds are active.

And one more thing. If you are really wanting to read about turf, I have updated my last blog post about an eclectic reference list, so that each article or book that I cited now has a link to the item. I cited articles from 1859 until 2012, and you can get the full text of most of the items for free. Have a look, and see if you find anything interesting.

High expectations


I've rarely been so excited to read an article. Last week when I saw Energy use and greenhouse gas emissions from turf management of two Swedish golf courses, by Tidåker et al., I immediately dropped what I was doing and read it.

If you've talked with me about turfgrass management sometime in the past 18 months, our conversation may have touched on differences in energy use, and the difference in carbon emissions, caused by differences in grass selection and maintenance practices. In fact, this is one of the topics Dave Wilber and I discussed as part of our wide-ranging conversation during episode 14 of the Turfgrass Zealot Project. I don't know how to make these calculations yet, but finally with this article I've read something that provides the calculations, and that I can study so I can figure out how to do this myself.

Gelernter et al. wrote in 2014 about quantifying sustainability on golf courses. We suggested measuring and tracking the annual:

  • quantity of fertilizers applied
  • quantity and toxicity of pesticides applied
  • quantity of water used
  • fuel volume
  • labor hours
  • electricity used

One can keep track of those quantities, together with the associated costs, and from that one can check the efficiency of the operation. These quantities also serve as some of the basic data requirements for the GEO OnCourse program.

But the quantities we wrote about in the GCM article are all different: kg of N, kg of fungicide, L of water, L of diesel, kWh of electricity. By expressing all the turf maintenance activities in units of greenhouse gas emissions (expressed as CO2 equivalents) or energy use, one then has a single number for the entire course, or for an area of the course, or per square meter, that can be used to compare to other courses next door or around the world. And the use extends well beyond comparisons to other golf courses; one can use these units to compare the maintenance of a golf course to anything that has greenhouse gas emissions or energy use.

I had high expectations for the article, and I wasn't disappointed. The authors described the fertilizer rates, topdressing rates, water use, mowing frequencies, and much more, for the two courses, and then expressed those units in GHG or energy use. N rates were up to 22 g/m2, as were K rates (I think the rates for golf course turf in Sweden should usually be less than reported in the article -- using precision fertilization, or temperature-based growth potential and MLSN, will lead to lower recommended amounts of fertilizer). Sand topdressing on greens was about 10 mm/year. Irrigation of greens was about 300 mm/year. Mowing of fairways was about 85 times/year, and greens were mown about 180 times/year.


I think this is fascinating because one can consider Sweden to have relatively low inputs. If you're familiar with golf course maintenance in a tropical environment, let's say in Phuket, you might expect fairways to be mown more than 150 times a year, greens more than 300 times, about double the fertilizer, and more than twice the water use. Now imagine what happens when comparing irrigated vs non-irrigated rough? Seashore paspalum wall-to-wall vs. manilagrass? A 60 ha sandcapped golf courses vs. one with drainage and 2 cm of sand topdressing? Overseeded vs. not? The differences in energy use and greenhouse gas emissions will be huge.

What did Tidåker et al. find in their analysis? The entire paper is worth a careful study, but in summary they found mowing was the most energy-consuming activity, and mowing together with the production and application of fertilizers (especially N) contributed the most to greenhouse gas emissions. They suggest:

Appropriate measures for reducing energy use and carbon footprint from lawn management are thus: i) reduced mowing frequency when applicable, ii) investment in electrified machinery, iii) lowering the mineral N fertiliser rate (especially on fairways) and iv) reducing the amount and transport of sand for dressing. Lowering the mineral fertiliser rate is of particular importance, since GHG emissions originate from both the manufacturing phase and from N turnover after application.

Jason Haines has some interesting reads about how turf condition can be improved while at the same time reducing inputs: