An MLSN Refresher


Not everyone understands how the MLSN guidelines work. I saw a recent conversation started by Andrew McDaniel followed by a number of posts from STSAsia exhibiting confusion on the latter's part about the use of the MLSN guidelines.


To paraphrase Brian Ripley, "Once you appreciate that you have seriously misread the guidelines, things will become a lot clearer." I'll take the opportunity here to write a short refresher about MLSN.

The grass is growing in soil. That soil has a certain amount of nutrients in it. We determine that quantity of nutrients by doing a soil nutrient analysis (a soil test). The amount of nutrients in the soil will change tomorrow, and the next day, and into the future, based on how much we apply as fertilizer, and based on how much the grass uses. But we can use this number. I'm going to call this soil number C. That's the quantity of a nutrient measured by the soil test.

On its own, that soil test number isn't useful for anything. I need to compare it to something. How about comparing the amount of a nutrient in the soil to the amount of a nutrient the grass will use? Now I am introducing a time component, because the grass use during 1 month of dormancy is different than the amount of grass use during 1 month of active growth. And the amount of use for 1 day is different than the amount of nutrient use in 1 year. And as STSAsia pointed out, the use is different in different locations. And the use is different for different grasses. Use of the MLSN guidelines explicitly accounts for the expected use of nutrients at any location. Let's call the expected use by the grass A.

Now we have two quantities. We have A, which is the amount the grass will use. And we have C, which is the amount in the soil. It would seem that this is enough information to determine a fertilizer requirement. We could say if A is more than C, then we definitely need to add the difference, because otherwise the grass will use more than the soil has. And we could say that if A is smaller than C, we don't need to add that element, because the amount the grass will use is less than the amount in the soil. And that is sort of how it works, but the MLSN guideline adds a buffer of extra nutrients that the grass will never touch.

The MLSN guidelines are added to the amount the grass will use. We can call the MLSN guideline amount B. The amount B is a quantity of nutrients that we always want to remain in the soil, untouched by the grass. So we take A, the amount the grass will use, and add to it B, the amount we want to keep as a reserve in the soil. We then compare A + B to C, and that difference becomes the fertilizer requirement. In that way, the site specific and grass specific and climate specific characteristics of each location are considered, and then an appropriate fertilizer recommendation is made. This fertilizer recommendation for each nutrient is based on how much the grass will use at each site, it accounts for keeping a reserve of nutrients in the soil (the MLSN guideline), and for how much of an element is actually in the soil at the time of sampling.

paceturf made the calculations for nutrient requirements at Fukuoka and Kuala Lumpur. Although the MLSN guideline is the same at each location, the nutrient recommendations will be more than 4 times higher for Kuala Lumpur than Fukuaka.

The MLSN guideline values are the only thing that stays the same. These represent a buffer amount of nutrients in the soil that we don't want the grass to use. Then the site specific values for estimated grass use of each element, and for the actual soil test at that site, make the MLSN approach suitable for just about every environment.

For more, see:

"Even though most are not labeled as K fertilizer, it's there"

I recently received this inquiry:

"What is your approach to K fertility with regards to phosphite products? Even though most are not labeled as K fertilizer, it's there."

That's correct for products that include potassium phosphite. I'm not sure how all phosphite products are labeled. Here's how I answered:

"I would count the K in that type of phosphite product as a K fertilizer addition.

I would ignore the P from phosphite, not counting it as a P fertilizer addition."

For more about phosphite, I recommend Penn State's Understanding the phosphonate products.

"I've waited far too long to voice my opinions concerning this extraordinary profession of greenkeeping"

How's that for a start? "The Walking Greenkeeper" introduced himself this morning. I expect this will be a fun blog to read.

Selection_010Now for an assortment of things that came to mind today, all of which are in some way related to Joe's blog post.

He wrote about some of his research this winter. Among other things, he mentioned me, MLSN, Jason Haines, and Chris Tritabaugh. "These fellas," he wrote, "and what I consider to be their alternative style to greenkeeping have inspired me ..." -- that's awesome.

So what came to mind? First, the #MLSN approach is about something very specific -- making fertilizer recommendations from soil tests to prevent nutrient deficiencies by ensuring the grass is supplied with enough of each element. However, the approach we have taken with MLSN has attracted interest from turf managers around the world who are interested in minimizing other inputs as well. And it is a lot of interest. I've been surprised that the MLSN newsletter mailing list, started just 6 weeks ago, already has more than 300 subscribers, from more than 30 countries.

If you are interested in the MLSN approach, you can subscribe to the newsletter here.

If you want more than just MLSN, you can sign up to the ATC newsletter here.

Here's an interesting question. Just what is the MLSN approach? Nadeem Zreikat wrote that he prefers efficient to minimalist:

Here's how I'd describe it. Lots of people are interested in MLSN and in the idea of managing things as efficiently as possible. I'd describe what I try to do, and with MLSN as a part of that, in this way:

For turf management at any site, the first thing to do is to define the conditions that one is trying to produce. Then, produce those conditions with the fewest possible inputs.

One could describe that as efficiency, or as minimalistic. I think both words, and many other words too, can fit the MLSN approach.

I wrote more about that in the Short Grammar of Greenkeeping. To produce the desired conditions, the turf manager manipulates the growth rate. In the Short Grammar, I wrote that greenkeeping can then be defined as modifying the growth rate to get the desired surface conditions. And the grammar provides a framework for adjusting the inputs to produce the desired conditions.

If that all sounds really vague, you'll want to read a great description of that approach in practice. I recommend Jason Haines' Turfhacker summary of everything that's interesting to me as a description of how these principles can be applied.

The whole idea is to produce the conditions we want, doing so with the minimum amount of work. Maybe that's efficiency, or minimalism, or sustainability, or something else. But that's where I'm coming from, that's the type of definition that the MLSN approach fits into, and this is for any type of turf.

I made a huge omission in last month's roundup. I forgot to include the 2016 Ryder Cup: Hazeltine National Turfgrass Team video featuring Chris Tritabaugh.

2016 Ryder Cup: Hazeltine National Golf Club, The Turfgrass Team from Chris Tritabaugh on Vimeo.

This is part of the approach too, and the video shows it. Be passionate about the work. Produce the conditions one is trying to produce. Do so with a minimum of inputs. Or as efficiently as possible. Have fun doing it. Find ways to do it better.

I expect everyone in this business is doing that in some way. It seems to me that the MLSN and Short Grammar approaches have provided a framework from which we can all work on and compare ways to do it better.

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.