"He's starving his greens"

This was a quiet comment I heard at a talk I did recently about my experience with the MLSN. This is something I hear a lot and a source of some confusion that I hope to clear up.

To apply this little fert safely you need to know what and when to apply it. It's all about timing.

A lot of people associate the MLSN with reducing fertilizer. This can be the case with nutrients that are in excess in the soil but my fertilizer reductions haven't been the result of using the MLSN entirely. If you are removing nutrients from the system you will eventually need to add those back in the form of fertilizer.

If you read closely on my blog you will learn that the huge reductions in fertilizer on my course have been the result of using soluble source fertilizers, halving my nitrogen rates all across my course, and simply withholding nutrients on my fairways as a Park Grass Experiment inspired experiment. The lack of fertilizer on my fw has nothing to do with the MLSN.

For the first year or two of using the MLSN I applied very little potassium but quickly had to bring the K back into my fertilizer applications as it is one of the nutrients used the most second only to nitrogen in the plant. It also leaches readily which is a big deal in a wet climate such as the one I'm in on the West Coast of Canada.

Yes the MLSN has helped me reduce or entirely eliminate the applications of calcium, phosphorus, and most micronutrients. This has saved me a few dollars here and there but I highly doubt that a significant portion of any fertilizer budget is for these nutrients. If it is I think you should take another look at your fertilizer inputs and needs on your course. By far the biggest fertilizer costs on any golf course will more than likely be nitrogen and potassium, both things that I apply to my greens and tees. The largest area of any course is probably the fairways so any reduction you can make there will have huge impacts on your fertilizer budget. As I said before, I'm only applying nitrogen to my fairways so the savings from the potassium I used to apply are huge.

Not bad for only nitrogen and wetting agents for inputs on fairways.

If anything the MLSN has taught me that we don't need as much fertilizer or nutrients as we used to think we needed. It has also helped me understand things such as the  park grass experiment. I have been purposely withholding potassium from my native soil fairways for 3 years now. We return the clippings so the losses of potassium from the soil should be minimal on these high CEC soils. I will be testing them this year to make sure.

The reason I'm doing this is to see what effect, if any, this will have on  weed populations on my fairways. We haven't used a herbicide on our fairways in at least 15 years and for the most part they are weed free. I guess that all depends on your definition of a weed but overall they are a visually appealing surface that is ideal for golfing on.

Some might see the low overall rate of nitrogen I have been applying to my course as "starving" my turfgrass. The reason I can safely go so low with my nitrogen rates is that I am using the growth potential formula as a guide to help me get into the ballpark for nitrogen rates and timing based on the average air temperatures each week or month. I then use my eyes to adjust based on growth rates and amount of play we are receiving (we have had our busiest winter ever and I've never applied less nitrogen through the winter and the greens have handled the traffic with no issues). The following table shows the average temps for each month and the very rough nitrogen rates I apply.

Month	Average Temperature	Growing Potential	N requirements (g/m²)
January	3.3	0.01	0.028
February	4.8	0.02	0.061
March	6.6	0.05	0.144
April	9.2	0.15	0.407
May	12.5	0.39	1.105
June	15.2	0.68	1.913
July	17.5	0.90	2.525
August	17.6	0.91	2.546
September	14.6	0.62	1.729
October	10.1	0.20	0.554
November	6	0.04	0.110
December	3.5	0.01	0.031
		Total N requirements per year	11.15

While I apply virtually no nitrogen for half the year, my grass doesn't require it as the air temperatures are too low for vigorous growth. Applying nitrogen during this time of the year only increases fusarium activity, money spent mowing, and thatch.

Fuzzy grass in the winter despite receiving no fertilizer applications 

Summer conditions

During the summer months I probably apply more nitrogen than most because the temperatures are ideal for cool season turfgrass growth. This increased nitrogen rates during the summer has helped me reduce moss and manage diseases like dollar spot and anthracnose without the need for pesticides.

Does this grass look starving?

It's all about timing. I used to apply nitrogen based on the theoretical ideal cool season growth curve but later discovered that cool season grass grows very differently based on the climate you are in. This is why I can apply much less fertilizer now than I used to. I only apply it if it is needed based on the temperature and what I am observing on the course. I used to apply the majority of my fertilizer in the Spring and Fall where I now apply the majority of my fertilizer in the Summer.

Not starving despite receiving only 2.25# N/1000 sq ft (12g N/m2) per season

I hope that people will continue to learn and read about the MLSN because it has the potential for some savings in fertilizer but I think the biggest advantage it has is that it will eliminate fertilizer applications that will make no difference to your turfgrass performance. This should theoretically help your operation be more sustainable and reduce the environmental impact that excessive fertilizer applications can have. If you want to find additional savings look into simple soluble source nutrients and the growth potential formula to fine tune your application timing and rates for your specific site. Happy MLSNing!