Wednesday, 27 June 2018


This year I changed my approach to topdressing on my greens. I decided to use clipping volume to determine how much and when I would topdress the greens. The idea is that I will apply sand as the grass grows and hopefully eliminate layering from heavy, infrequent sand applications. My nifty HUD knows how much clippings I have removed from my greens and how much sand I have applied to them. It can then display the sand requirement in a way that makes sense to me.

Sand-O-Meter this morning before applying sand
Sand is applied

Sand-O-meter is automatically updated after I record my sand application into my online records.

I have always guessed at how much sand I need to apply which is a big problem. Sand is now the single most expensive input on my entire golf course and I only apply it on greens! ($2000 in previous years with a target of $500 this year) Just like I was guessing how much I aerify, I decided that if I wanted to refine my sand application practices (and be able to adjust them each year in a meaningful way,) I needed to do better.

Just like with fertilizer, water, and pesticides, no two years are the same for their requirements on your golf course. Using dates on a calendar to schedule maintenance practice such as these just doesn't make sense because Mother Nature doesn't give a shit what day of the month is it. If we want to refine things, we need to base our practices on the actual observed conditions.

a light blow and turn of the heads and they are looking good!
What makes sense to me to base topdressing requirements on is how much growth we have. More growth equals more organic matter production right? I mean, it's probably more complicated than that but in general terms that's kind of how it works.

So after over 6 seasons of collecting and measuring clippings on my greens I have a pretty good idea of how much grass I will harvest. I also have a pretty good idea of how much sand I used to apply.

This is where it gets a bit experimental for me. I'm hoping to reduce thatch accumulation on my greens through careful monitoring of nutrients added vs removed and in theory I hope to keep organic matter production to a minimum but who the hell knows eh?

So, I picked a number that is a lot lower than I have previously applied and will adapt from there. I'm hoping to not have to aerify much or at all so that amount of sand was removed from my numbers. If my chosen annual rate of sand per unit volume of clippings is a bit low, I can adjust it up and if it's a bit high I can adjust it down. In a year where I grow more grass I will automatically apply more sand and in years where there is limited growth I will apply less. Awesome! After a few years I should come to a good number for my course.

The math is simple.

I am applying 227g sand/m^2 per 1g Nitrogen/m^2 removed via clippings. Why this number? I guessed and will adjust it based on soil tests and physical greens properties tests.

To make it more user friendly for me and my staff I converted grams of sand/m^2 into a unit I call "tractor scoops". This is how many scoops are required from the tractor to apply that amount of sand. One hopper in our topdresser holds 2 scoops. Typically a light dusting here will require 4 scoops or 2 hoppers to do. This is an amount that I can apply any day of the week with minimal disruption to golfers but also won't result in me having to apply sand more than once every 3-4 weeks throughout the growing season.

To determine the mass of a scoop of sand you need to first take a scoop of sand with your tractor. Fill a pail with sand and dry the shit out of that sand. Then measure the mass of that pail of sand.

Then see how many pails of sand 1 scoop of your tractor can fill. This entire process took me a half hour. Hint: a tiger torch and a concrete mixer work great for drying sand.

Now you know how much a tractor scoop of dried sand weighs. You also know the volume because you know the volume of that pail right?

For me, one scoop of sand weighs approximately 360 kg when dry.

It is also 228,000 cm^3

1 scoop of sand on 1000m^2 is about 0.23mm thick of sand.

So at the end of the season I will be able to see if that 227g of sand per g of nitrogen removed from clippings is enough and can fine tune my sand applications from there. The ultimate goal is to use as little sand as possible because, hey, it's a non-renewable resource.

Tuesday, 26 June 2018

Growth Rate and Plant Health Hypothetically speaking....

Place looks better in late June that it did in May. Gotta love Junuary!
In my last post I wondered if I could use indicator species to help me grow my grass at the right rate. This is only a hypothesis but is what I have been trying for the past few seasons and it seems to work from what I've seen. Either way, It's not fact and could be total bullshit.

I wonder through, hypothetically speaking, if grass is healthiest (has the least amount of disease) when it's growing at the appropriate speed for the climatic conditions, what are the consequences of, say, using preventative fungicides and growing the grass at the less than optimal rate? (because hypothetically speaking the only way to truly grow the grass at the right speed is by not applying preventative fungicides and seeing the disease)

The more I think about it (if my thinking and observations are true) the only real way to truly achieve the optimal growth rate for plant health (again, less disease) is to use the actual diseases to help you fine tune things. So if this is true (not likely) then what kinds of other issues are we going to get if we mask the diseases with regular fungicide applications?

I'm building hypothesis on top of hypothesis here so this is so far fetched it's not even funny.

Also understand that what I'm trying here is to grow grass without any fungicides, organic or synthetic because I'm not convinced organic is any better than other ways of managing turf. It's all shit! (just kidding)

Is this (sub-optimal growth rate) one of the reasons some people experience major disease outbreaks as the previously applied fungicide wears off?

I know that's probably what I used to observe back when I used a lot of fungicide and had poorly timed fertilizer applications. I applied most of my nitrogen in the spring and fall as the "classic" cool season growth curve suggested I do. I was growing my grass the fastest when my fusarium and growth potential curve were suggesting I grow it slower. In the summer months I was growing the grass slowly when the dollar spot and growth potential curve were suggesting I grow it faster (for my climate anyway). It's no wonder I would get absolutely hammered with disease when I managed my turf this way. I was chasing my tail and putting out fires left and right! Maybe it's not directly a result of the fungicide killing of beneficial organisms as some would suggest, but a combination of that and grass that is growing at the wrong rate. Who the hell knows eh?

The 8th green is growing too slow and has the most dollar spot so I have it some extra nitrogen today.
Dollar spot on the 8th. Interesting how it seems to be on the margin of the bentgrass patch.
It's also no wonder why we had so much poa on our greens because we were constantly killing our grass and the only thing that was saving our ass was the constant supply of poa seed.

What about thatch? Thatch relies on the soil microorganisms to break it down otherwise we are left to physically dilute or remove it through mechanical means. If we are matching growth rates to the soil/plant biology then perhaps we can eliminate or reduce the inevitable organic matter buildup in our soils?

What about plant health in general? The plants ability to be healthy and tolerate traffic and stay nice and dense and competitive? Lucky for me most of our traffic comes at times of the year where growth rates are the highest. It's almost like the ideal conditions for golf are also the ideal conditions for grass growth.

Of course there are going to be times when you need to grow the grass at a rate that will make disease worse. Clubs with high amounts of traffic in the winter months where the grass hardly grows and courses that absolutely need slow growing grass for tournaments in the summer months. I don't think there's any getting around those situations but thankfully most lower end clubs don't have those pressures.

Boy would I love to see some solid research on this.

Clearly I've been thinking too hard.

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We have never done less or spent less on our greens

Monday, 25 June 2018

Using indicator species to fine tune fertilizer applications

I get it. I talk a lot about turf disease and fertilizer but it is only because I think that the two things are closely related. More specifically, I think the amount and types of diseases on our grass are closely related to how fast the grass is growing.

Not too shabby
From what I have seen over the past few years of intense growth rate monitoring and reduction in fungicide use is that if we can grow that grass at the right rate, we can reduce the amount of disease significantly.

The trouble is that it isn't that easy to figure out what is the right speed. Further complicating matters is that if you add too much fertilizer, you cannot take it back and are stuck with grass that is either growing too fast which can lead to all sorts of issues at certain times of the year.

I have used the Growth Potential mathematical model to predict nitrogen needs, clipping volume and many other things to try and help me get it right and each year that I further refine my fertilizer timing and rates, the less disease issues I have.

One of the first strategies that I used when starting to really try and reduce my reliance on fungicides was to simply not apply preventative fungicides and use my observations to try and figure out why my grass was diseased. I could never understand why some areas were covered in disease and others were untouched. It started with obvious things like sunlight, drainage and disease spread but then focused on how fast my grass was growing. Grow it too fast and it gets disease, grow it too slow and it gets disease. Grow it just right and there is little or no disease. It sounds too good to be true and it might just be. We have to maintain playing surfaces after all and we can't just grow our grass at speeds to reduce disease. We need to grow it at speeds to manage wear and tear etc.

On a deeper level I think this all ties together with the soil microbiome and that thing called balance we all seek to achieve.

Growing the grass at the right speed isn't that easy because the right speed changes every day! How can we consistently hit this moving target? The mathematical formulas can help but they aren't perfect.

What if I go back to my first disease management strategy and let the disease tell me how much I should fertilize my grass and when and combine these observations with the data collection and growth potential model?

I think it might just work and if you have read some of my recent posts you will know where I'm going with this.

Here are a few of the common turf diseases I deal with and how they can help you refine your fertilizer (and cultural) program and hit that sweet spot with more consistency.

You can further refine things if you fertilize greens individually based on their growth rates and disease levels like I have done for the past year. It's not that hard to do either. Fill up your tank with water with enough to spray all greens. Add the stuff you need to apply to all greens like wetting agents etc. Go spray the greens that don't need any fertilizer. Add some fertilizer. Go spray the greens that need some fertilizer. Add more fertilizer. Go spray the greens that need even more fertilizer.


This disease is mostly a problem in the winter months but I have seen it every month of the year! To me it indicates that the grass is growing too quickly and no additional fertilizer is needed (unless damage is widespread and you need to fill in the dead spots with the aid of a fungicide).

I have noticed that the Smith-Kerns dollar spot model does work for fusarium at some times of the year but I eagerly await the upcoming release of a fusarium specific prediction model to make managing this disease and my plant growth rates that much easier.

Fusarium in June! With elevated growth rates and a brief cool and wet week the disease popped up. Luckily it dried up and warmed up and it went away.

Dollar Spot

This disease is only an issue here in the summer and only on the slowly growing greens. To me dollar spot indicates that the grass is growing too slowly for the conditions and more nitrogen is needed.

The Smith-Kerns dollar spot model is awesome and when I see disease pressure spike I check my clipping volume data to ensure my grass is growing fast enough.

A light spike in disease pressure saw some disease on our greens.

I find that a growth rate of 20ml/m^2 per day is sufficient to manage dollar spot in most cases.


This disease has only become a problem on my greens in recent years I have have consistently reduced my annual nitrogen rates each and every year since 2012. This disease indicates that the grass is growing too slowly and more nitrogen is needed unless you are a sick bastard like me who likes to see the poa die. On our predominantly bentgrass greens I don't adjust the growth rate and just let the poa die.

anthracnose on my first green
As can be seen on the lower chart, my first green has been growing slower than most while receiving the most nitrogen fertilizer to help manage anthracnose on that green.

While still obviously infected (great time to drop some seed), the green is still alive with the additional nitrogen treatments. 


This disease is only an issue in wet summers or if I get lazy and overwater the greens. Dry them out and incorporate some 21-0-0 into your nitrogen fertilizer treatments and it should go away. Needless to say, I haven't seen this disease in years since I stopped being so lazy and started using more 21-0-0.

Brown Patch

This disease used to be a big problem on our greens but we haven't seen it since we stopped watering in the afternoons. Let you grass be dry for as long as possible to keep the humidity down during the heat of the day.


Not a disease but a great indicator species as well. In 2012 our fairways were thatching, soft and didn't drain very well. I decided to try and use less nitrogen to see if we could do something about the thatch. Each and every year I applied less and less fertilizer and the fairways improved more and more until this year when the weeds took over.

What I think happened is that we finally burned up the excess organic matter and now the grass isn't getting enough nitrogen to compete with the weeds. This is a great indication (along with the fantastic drainage and firm conditions) that I need to fertilize my fairways slightly more if I want to keep weeds to a minimum without the need for a herbicide. Even then, the fairways will always be the weakest part of the course until we can renovate them to smooth out the settling that has occurred over the past 30 years.

So while we have a lot of high tech tools available to help us make decisions I think that we can also use turf diseases to do similar things. The diseases are reality and the models are just theory. Ideally we want to prevent the disease in the first place so I still think the high tech tools are essential for keeping things balanced and understanding why the disease is an issue and how you can take action to correct it before it becomes a costly issue. We can use the growth potential model and clipping volume data to get into teh ballpark then if we pay close attention to these diseases (assuming you don't apply preventative fungicides) we should be able to adjust our maintenance practices to hit the sweet spot. And about that playability thing....for me at least, they two things are also closely related. Healthy grass = good surfaces for golf!

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Thursday, 14 June 2018

Is Feast or Famine Better than Light and Frequent?

This is what I call "DiseaseyAF" weather
This past week I gave my greens a reasonably heavy fertilizer application (1g n/m^2 (0.25# N/1000) as all the signs I had were suggesting that my greens needed more fertilizer. The poa was thin and weak from just coming out of the seed head flush and was covered in anthracnose.

early signs of anthracnose this past week
I took this opportunity to spread some bentgrass seed as the competition in the next few weeks from the poa will not be very high and this is ideal for seedling establishment.

Not surprisingly, 2 days following the fertilizer application our growth rate skyrocketed and it appears that the anthracnose destruction has slowed which is what I wanted. I want thin, weak poa and the anthracnose is one of the best selective tools (available in Canada eh) I can think of to do that.

A few days following the fertilizer app they are looking much better despite still being covered in disease. F yeah!

While out changing pins today I noticed that the diseased poa was still relatively stunted and slow growing but the bentgrass was surging with growth. I thought that maybe this could be a better way to promote bentgrass over poa annua. Instead of light and frequent feeding we could restrict fertilizer until the poa starts to show signs of stress and disease, throw down some seed, then hit them with a relatively high dose of fertilizer with the hope that the stressed poa cannot take advantage of the increased nitrogen rates as the bentgrass can.

It's just a thought.

We can combine this with measuring the clipping yield and estimating the amount of nutrient removed from clipping removal and adjust our fertilizer rates throughout the year to account of nutrient release from organic matter. This way we can apply relatively high fertilizer rates at some times of the year but also burn organic matter at other times of the year.

While I love the idea of simply applying very little fertilizer like some successful bentgrass growers do. I also think that it might not just be about applying less, but applying the right amount at the right time especially when we take plant health and the desire to use less pesticides into account. From what I have seen and learned over the past few years, we can probably significantly reduce our need for corrective pesticides if we can simply (not that simple) grow the grass at the appropriate speed for the time of year.

My observations about disease and growth rate were reaffirmed this last week when the increased nitrogen rates resulted in an outbreak of fusarium. This was fully expected but also not a worry because the weather next week will be too hot and dry for fusarium to last long. The fusarium is also only present on the poa so any more selective poa death right now is welcome.

Still no fungicides applied since Jan 9 2018. 155 days and counting
It's also worth noting that disease has been so low on my greens that I have dropped phosphite from my disease management program. I have required a fungicide every spring but this year (and last) I made it through without despite applying less and less pest control products. Maybe it's the weather because we had one of the hottest and driest Mays on record.

small patches of fusarium mycelium were visible this morning on the poa. GOOD!

So I think the plan now for fertilizing greens will be to monitor growth rates and poa health and hold off on fertilizer applications long enough to stress the poa and then follow it with a healthy dose of nitrogen to fill in the voids hopefully with bentgrass. Ever since changing the rates and timing of nitrogen on my course (thanks to the growth potential formula) I have made huge gains in bentgrass on our greens. I wonder if taking this a step further by deliberately stressing the poa during the high growth months while also providing the bentgrass with enough nitrogen to remain competitive will be a viable strategy.

There is a lot of talk about how if you want to promote bentgrass over poa you need to use less nitrogen which I think it partially true but like all generalizations I think this idea can be improved upon. While less nitrogen is probably key, bentgrass isn't going to grow quickly enough to fill in the voids if we are trying to convert from poa to bent. Maybe if we can do a bit of both with this approach we will be able to get the advantages of both low fertilizer and high fertilizer rates to achieve our goals of having more bentgrass?

There's only one way to find out I guess.

This is, of course, subject to constant change.

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Monday, 11 June 2018

If I had a magic 8 ball

It would probably read,

"All signs point to fertilizing more!"


Despite my lack of a magic 8 ball I do have the next best thing. A HUD (Heads Up Display) which shows all my course data. This is supposed to help me make better decisions by automatically analyzing the data I collect and presenting it in a single place for my observation.

When I combine what the HUD is showing me with my disease observations it becomes clear what I should do and what I should do is fertilize my greens more. You might be thinking what's the big deal, just apply the fertilizer already you asshole! You are probably right but the reason I am so hesitant to apply fertilizer is that once you apply it, you can't take it back. As fertilizer has such a big impact on turf conditions and the costs associated with maintaining the golf course I need to be absolutely certain that the fertilizer is needed. So far this year we have mowed less than ever before. This has big impacts on fuel use, mower wear and tear and labor required to maintain the course. Growing the grass faster than absolutely necessary just wastes money.

1. Greens are lean

So far this year we have only applied 2.9 grams of nitrogen per square meter on our greens (0.64# N/1000). Through the measurement of our clipping volume I have been able to watch how much nutrients we are removing from our greens and compare that to how much we have applied.

In the last month we have removed more nutrients from our greens that we added. It's obvious from the chart below and it's also obvious with how visible the #friskyfairyring is on the greens. Bottom line, they are lean!

This fairy ring has never been visible on our greens. Bottom line, they are lean AF right now.
Wow, those greens sure are lean. Don't need a stupid graph to tell you that!

I know, I know, but having the data helps me understand how lean they are and why. In this case they are lean because we have applied less nutrient than we removed in the last month.

2. Disease

This week anthracnose showed up on our poa. For most of my greens there isn't much poa so I can let it die a quick and painful death. My first green is still mostly poa so I need to slow the death down to a level that will see the surface covered in turfgrass while the recently seeded bentgrass has a chance to fill in the gaps left behind by the disease and poa seed head.

anthracnose is back and by the looks of it, widespread

bentgrass seeded into the voids left behind from the poa seed head and anthracnose

The BMP guide from Rutgers suggests that increasing nitrogen rates will lessen the impacts of anthracnose among other things. My goal is not to eliminate the anthracnose but to slow its destructive tendencies down a bit. Anthracnose is a great selective pathogen that will kill out the poa and leave the bentgrass relatively unscathed.

So the increased nitrogen rates are double beneficial for dealing with anthracnose. They slow the disease down and hopefully help the bentgrass fill in the voids a bit quicker. I applied 1g of nitrogen per square meter to our first green which is the hardest hit with anthracnose for a cost of $2 this week. As time goes on I will continue to add these relatively heavy fertilizer apps to manage the anthracnose on this green and others as required.

Growing the grass at an increased rate in the summer is also a good strategy for dollar spot and is one of the principle strategies employed at the Vineyard Club. This week we had dollar spot show up on our greens and not surprisingly our growth rates are well below that where I have observed are good for managing dollar spot.

Dollar Spot is back. F sake
Growth rates are currently below the dollar spot target

There was a spike in disease pressure yesterday. The DS action threshold is probably set too high btw.
Despite the high disease pressure last month, the increased growth rates were enough to keep the disease away.
So there you have it. Growing the grass faster than we currently are will help reduce disease. Why don't I just apply a fungicide? Well a fungicide costs about $600+ where increasing fertilizer will cost maybe $10. It just doesn't make sense to run to a fungicide (yet) when I clearly have options that are much cheaper and probably (hopefully) just as effective.

3. Greens are too fast

Our green speeds are too fast which isn't a bad problem if you are a good golfer. Our course is difficult enough and as we approach the busy season where there are many novice golfers playing we need to keep our green speeds down to keep the time it takes per round down. No one likes a 5 hour round. Either way, we can stand to have them slow down a bit without worrying about them being too slow.

Greens speeds are the high. Note the dip in speeds during the effing poa seed head flush.

The sure are fast downhill these days

So there you go. This is just one example of how I am using my HUD and the data collection to make better decisions (hopefully) about how we grow our grass.

If you like my blog and want to support what I do you can support me on Patreon or paypal. Thanks!

Friday, 25 May 2018

I got a drone! Thank you!

A few weeks while checking out twitter I came across the following tweet by Mr. Drone aka Thomas Bastis

Cheekily, I replied, "I wish" knowing that this wasn't something that I could afford, even used.

The next morning I woke up to find that fellow PNW superintendent, Ryan Gordon, had started a gofundme campaign to help me get Thomas' old drone!

At first I thought that no one would ever give me money to buy a drone. Afterall, drones are still considered by most to be a luxury item for golf course operations. To be honest I felt a bit bad to be the recipient of a fundraiser.

To my surprise after a few short minutes the donations started to pour in and after about a week almost $800 had been raised to pay Thomas for his old drone. Even though the fundraising goal was $1000 Thomas was happy to receive the lower amount and sent me the drone!

This is so cool.

Thank you everyone who donated and especially Thomas and Ryan for their generosity and thoughtfulness. I have big plans of how I can use a tool like this on my golf course and plan on sharing everything on this blog.

There's just one problem.

Flying a drone in Canada is very restricted. You can fly for fun in certain remote areas but if you fly for work ( which includes uploading video to youtube or a blog) you need a SFOC (Special Flight Operations Certificate). So unfortunately before I can share anything on my blog or online in any way (even likes are considered payment and would require a SFOC) I need to get a permit to fly. The fines are stiff at $30,000 so as someone with some social media attention, I am going to play it safe and do it by the book.

This is an involved process but something that I have already started to achieve. I need to complete aviation ground school, get a radio operators license, file a SOP, Safety Plan and many more things before I can legally fly. I hope to have all this done and be legal to fly some time in July (waiting period after applications are 20 days - 2 months). After I file a few successful SFOC I can apply for a standing permit which will allow me much more freedom of when I can fly. This should be easy to achieve on a golf course because it is very easy for me to plan long in advance of the SFOC flights that are required to achieve more freedom. I will share this process on my blog for those that are interested.

Either way, I am so grateful and humbled to be the recipient of such generosity and thoughtfulness from the turfgrass community. I can't thank everyone enough!


Tuesday, 27 March 2018

Measuring Putting Green Infiltration Rates

In my last post I discussed how too much aerification might be a bad thing and wondered if more is better or if there is an ideal amount of compaction that we can maintain to maximize soil health and help us reduce the inputs that we currently require to maintain our putting greens. Inputs like sand, fertilizer, tines, fungicide and water.

I then shared how my greens have never performed better based on some anecdotal observations.

Yesterday I decided that if I was going to try and aerifiy less or not at all that I would need to measure the things that aerification is supposed to manage so that I can track their change over time. Simply not doing something without knowing that it's working is simply a dumb thing to do.

As usual, there were a ton of products that I needed to buy to figure out this kind of hokus pokus but then I remembered that I'm not doing super precise science here. I want to get a general idea of how my greens perform and relate that to my observations on how they actually perform and meet my expectations for my course's specific needs.

I have always measured organic matter when I soil test so I don't have to do anything different here.

To measure the percolation rate you can buy all kinds of fancy tools to measure how fast water moves through the soil but I decided to do it on the cheap.

I used an old cup cutter blade and marked a line 6cm up from the bottom. This is how far I drive it into the green. I then fill it with water up to the bottom of the top ring and start a timer. I come back, record the time and how far the water has dropped. This gives me the infiltration rate in mm/hr.

It was raining so hard I needed to cover the top of the old cup cutter blade to prevent it from filling back up!
Is this method perfect? Not even close. Typically you would want a double ring tester where the larger outer ring is also filled with water but not measured. This reduces lateral water flow below the cup cutter blade. For my testing my soils were at or above field capacity (36%VMC) so I wasn't too worried about it. You could always hammer the cup in deeper to a point below the majority of the roots (for me this is 6cm) and forget about the infiltration rate below that point. 

You should also use a constant time to measure the infiltration rate because the rate can vary from the first few minutes as the soil saturates. Again, I'm not too worried about being super precise here. I just want to know if my greens drain good.

I have only found drain pipe in one of our greens. Guess which one? Regardless, they all drain better than is needed.

So how fast should the greens drain? According to this blog post by the STRI we should aim for drainage at least 15-25mm/hr. If you find a green with issues, ask yourself if the grass is bad because of it, then do further testing to see if it's an isolated issue or widespread. You can test various depths to see if it's a surface issue or an issue that needs to be addressed with drainage or deep tine aerification. I think you will find quite a bit of variation from one green to another and even across a single greens as the topography and distance from drain line changes. All we are trying to do here is look for issues and negative changes over time. If we find issues we can them make informed decisions about them and if there are no issues we can do nothing!

As you can see in the above chart, All my greens drain more than adequately despite hardly aerifiying them in the past years. I really wish I had data from years ago to compare because I have a hunch that they drain better today then any time in the past. I also wonder if they will improve with less aerification or get worse. The only way to know is to wait and see!

It will be interesting to see how these numbers change over time especially following a wetting agent application coming next week.

I have 4 old cup cutter blades so I can do the testing on a rotation. To do 12 greens it only took me 1 hour to test this so I will be testing this much more often in the coming months and years. It's a super easy test to do and if it can reduce the amount of aerification required, then it will more than pay for the effort required to do the testing.

I also started measuring soil bulk density. We want to ensure that the soil isn't too compact that we limit root growth. Maybe we can use wetting agents in the winter to move water through a compacted soil, but roots still need physical space to grow.
Measuring bulk density

To measure bulk density I also used an old cup cutter blade. I measured the cross section, calculated the area of the opening and then determined the depth I would have to drive the cutter blade to measure both 500cm^3 and 1000cm^3. 

I measured my cup cutter blade to have a diameter of 105mm. As we all know the area of a circle is Area = π r^2. Our radius is 52.5mm so the cross sectional area of our cup cutter is 8654mm^2 or about 86cm^2. To get the depth for a 500cm^3 cylinder we divide the volume by the circle cross section to get 5.8cm. Simple double that to get 1000cm^3 depth.

So we want to find out the density of the soil in grams/cm^3. This is our bulk density. 

To do this first weigh your cup cutter blade. Then hammer it into the soil to the 500cm^3 depth and measure the combined mass of the cup cutter blade and the wet soil withing the blade. Make sure the bottom of the cup cutter is full of soil and it isn't sticking out at all.

Subtract the cup cutter mass from the total mass to get the mass of just the wet soil.

Ok great, but there's a problem. The soil moisture content will vary and soil moisture has mass. To figure out what the soil moisture weights take a paper cut. Weigh it, then add a sample of soil to the cup and weight it again. Now we can figure out the mass of a small sample of wet soil. Microwave the wet sample until it is completely dry. I like to stirr the sample to let the moisture leave it quicker. We now can compare the mass of the wet sample to the dry sample. This will give us a percentage. Typically this is about 80% for my soils. Every sample will be slightly different. Multiply this percentage by the mass of the total 500cm^3 sample to get the dried mass then divide this by 500 to get the bulk density.

Depending on where you read, upper limits will fall anywhere from 1.6-1.8g/cm^3 with ideal limits around 1.25-1.35. I'm not too concerned with having minimum bulk density and more concerned with ensuring that it's not too high. 

Again, this isn't super precise, but it's good enough for our purposes. If you want more precision you can pay some companies a lot of money to do it for you.

As can be seen, my greens are all within tolerable limits. I'm not as concerned about the absolute values I measured, but more so in the change over time. As is, the greens perform better than expected so who is anyone to say that the numbers I got are bad?

The reason I am measuring this is to confirm that I don't need to aerify for drainage purposes. Most of the research about rolling and disease has found that infiltration rates weren't negatively impacted by double rolling daily so that I good to know for disease management. So if we can keep good drainage and optimize the pore spaces in the top few cm with rolling then maybe we can have the best of both worlds. If we measure the infiltration rates we can eliminate the guesswork and be confident that not aerifiying won't end in disaster. It can also confirm that aerification is warranted and make it much easier to justify this disruptive practice to golfers and management. If you don't measure this stuff you are simply guessing. 

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Sunday, 25 March 2018

Does Aerification Make Disease Worse?

Have you ever noticed a disease outbreak immediately following aerification?

I'm pretty sure most people have and this is why it is common practice to spray a fungicide before aerifying. Why does this happen?

I always blamed the disease outbreak on the mechanical stress we put the grass under. I also noticed that the abrasive practices used to drag the sand into the aeration holes would spread the disease like crazy.

Fusarium Spread from verticutting after aerification

Niels Dokkuma from the Koninklijke Nederlandse Golf Federatie visited my course in February of 2017 to see what I was doing to reduce the pesticide use on my golf course because the Netherlands are facing an almost complete ban on pesticides in 2020 so they need to learn whatever they can to avoid disaster.

He asked me a seemingly simple question. "Do you think aerification makes disease worse?"

Of course I agreed with him and went into discussion about how we spread the disease around and the mechanical stress that goes on etc. We pretty much left it at that but ever since that meeting I have been thinking a lot about this. 

Does aerification cause disease?

Does the physical act of increasing macropores in the soil make disease worse?

I know you're thinking this guy is nuts! Aerification is nothing but good, right? Aerification makes disease less bad, right?

Lets forget the pain in the ass that aerification is. Broken equipment, bumpy greens, huge expense  loss of revenue, and poa seed brought to the surface. Lets forget about the obvious downside of aerification and think a bit about how else it could be hurting our operation.

Check out the following video where Dr. Thom Nikolai discusses the "most significant discovery of his research career." If this is the most important discovery of his research career I wonder what the most important discovery of his not-research career is? 

The research that he and his associates did on rolling and dollar spot is some of the most interesting research in the world of turfgrass management in my opinion. In the following video clip he discusses why he thinks rolling reduces dollar spot.

Cool, so rolling reduces dollar spot. What about other diseases?

A few years ago I discovered that rolling reduces fusarium patch!

So wait, if rolling reduces major diseases like dollar spot and fusarium patch wouldn't that suggest that compaction (or compression of the top mat layer) reduces disease and not aerification? Isn't rolling the exact opposite of aerification?

We all see the disease following aerification, see the results that compacting or compressing the soil can have on disease then say that aerification reduces disease!

Sounds a bit backwards to me! Sounds like a lame justification to do a practice that none of us like doing too. It's required to manage organic matter, infiltration rates and disease.


Maybe if the soils have been allowed to get to a point of neglect aerification will help but I think that with the tools and knowledge that a typical superintendent has available, we should be able to forget about the blanket aerification practices that are so common in our industry.

We've all heard of the general recommendations for aerification. Anywhere from 10%-20% surface disruption to ensure we don't run into trouble. This is probably a great general recommendation but it doesn't take your specific situation into account and this is one of the reasons I hate generalized agronomic recommendations. Every course is different. Different climate, different grass, different construction, different amount of traffic, and different budget.

If we are measuring clippings and only applying fertilizer to make the grass grow faster when required we should be able to make better use of the nutrients release from the soil organic matter and therefore use up that organic matter instead of continuously add to it. Add to this topdressing as required to keep the organic matter in check as determined by regular soil testing we should be able to eliminate the need for core aerification to remove excess organic matter. If we can be more precise with our fertilizer applications and growth rates we should have less waste and therefore less need for corrective maintenance practices.

What about infiltration? Surely aerification helps with infiltration! Yes, we've all seen the videos of an aerifier running over a puddle on a putting green and watched the water disappear almost instantly. I've always done this and even left the holes open during the winter to help aid in the drainage only to find that a few weeks following aerification the greens would puddle and we would be back to square one.

This winter I decided to try something new. I tried aerifying less aggressively and decided to use a penetrant (wetting agents, what's the difference?) through the winter. I don't have any quantitative data on this yet but what I can say with almost certainty is that our 30 year old greens have never drained better!

Our 4th green is severely sloped towards a sand trap and for the 17 years I have been here the sand trap would wash out every time it rained. This February we had a rain event that dropped over 100mm of rain in less than 24 hours.

The typical situation on our 4th green. This as the only time this winter we had a washout due to frozen soils.
So I went out to repair the trap in the morning to find that it wasn't washed out literally for the first time in 17 years! The bottom of the trap was full of water because it just rained 100mm and we don't aerify or spray wetting agents in the traps (maybe we should?).

This observation suggested to me that the rain went down into the soil instead of running across the surface and into this sand trap. All winter this has happened except for during the snow melt where the putting green soil was frozen solid and therefore not able to drain properly. Knowing if drainage is good is now very easy. If that trap washes out, I need to improve drainage. If it doesn't wash out, drainage is within tolerable levels and better than any time before 2018 in the club's history! No fancy tools needed although I am going to look into getting a way to quantify infiltration rates better.

So has aerification helped my greens drain better in the past? Not from what I've seen. Maybe it will get worse with no aerification so I will watch this in the future to make sure that they continue to drain as expected.

I think a lot of our issues with water infiltration come down to hydrophobic soils and I wonder if aerification makes this worse as well. When we aerify the greens we create these awesome holes for the water to flow down. Water is lazy so it always takes the path of least resistance and this can be called preferential flow in soils. If all the water is flowing down these few channels what is happening to the water and the soil surrounding these holes?

We have all seen the nice green holes following aerification and I wonder if it is that the grass in the holes is healthier or if the grass beside the holes is suffering because it is getting none of the water and gas exchange because of preferential flow. If we only disrupt 10-20% of the surface does the other 80-90% suffer?
Testing soil bulk density. Is the grass greener in the aeration holes or is the grass less green because of the aeration holes?
It's a really easy thing to try. Spray a penetrant on your greens in the winter and see if drainage improves. I think you will see that you get better drainage than ever before which makes me wonder why we would need to aerify to improve drainage if it only improves things for a short time and not even in a significant way?

The video below by Pace Turf shows how this phenominon can impact soils that are high in salts.

When it comes to hydrophobic soils I wonder if aerification makes it worse by drying out the soils surrounding the holes. In the winter time we don't notice the hydrophobic areas because et rates are low and precipitation is high but as soon as it warms up we see the same localized dry spots in the same location year after year.

What if we don't create preferential flow opportunities and just use penetrants to uniformly wet the soil all winter long. Will that help our localized dry spot issues in the summer? I've heard some talk of this in Scotland and I think there might be something to this idea. Bottom line, my greens have never been drier in the winter or drained better.

So what about aerification makes disease worse? In Nikolai's rolling research they found elevated levels of beneficial bacteria in the soil as a result of the rolling. It wasn't dew removal, it was the soil biology that they think were making the difference. It also appears that a more compressed soil favors bacteria which could compete with the fungi that cause all our problems.

So I think we need to focus on when it comes to soil aerification is to determine what is the optimum compression or compaction and work to keep our soils within tolerable limits.

The look of the profile continues to improve despite less aerification than ever before.
Maybe this is why most people see so little success with compost teas and bio-amendments. If you add these beneficial organisms to an environment that isn't ideal for them, they simply die. Hey Rob Wilke, do your soils ever dry down up there? Maybe the success Rob sees with compost and wood has a lot to do with almost constantly saturated soils in one of the rainiest places on earth. Wet, slightly compacted soil is ideal for bacteria that compete with the fungal pathogens..... Maybe too much air is a bad thing?

I'm over aerification. Instead, I have started measuring the physical properties of my putting greens and will monitor them over time to see if they change or fall outside of tolerable limits. I will try and avoid issues with compaction, excessive organic matter buildup and drainage without poking holes but will still keep aerification as a tool in case some areas run into trouble. I am currently measuring soil bulk density, infiltration rates and organic matter content. By tracking this over time on my HUD I should be able to make better decisions about when and how I aerify my greens, if at all.

Maybe we can find out what the ideal soil properties are for healthy soils and stop the ideas of more is better when it comes to aerification because the way I see it, more is definitely not better. I think a lot of our reliance on aerification comes from not measuring our soil properties and simply guessing too much. Maybe we can aerify less, and improve conditions?

Or maybe I'm completely insane......stay tuned to find out!

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Friday, 9 March 2018

Low Cost Surface Firmness Tester

If you're a broke datahead like me you probably have always wanted to measure your putting green surface firmness but haven't been able to justify the $1000+ expense to buy one of the fancy testers available on the market. The problem I have had is that I just wasn't sure if it would be a metric that would make a difference in the way I managed my golf course.

It was easy for me to justify the expense of a moisture meter almost 10 years ago because I could see how it would improve my operation. I'm still on the fence about the firmness tester so I asked twitter how I could make one for myself and as usual, was pleasantly surprised.

This rather simple firmness tester was brought to my attention but it was still out of my price range at around $500.

Dr. D made a great little video outlining these various devices and how they work.

I decided to make an even cheaper version than what the PGA currently uses, again, because I am not sure if this is something that is valuable to me.

I bought 2 steel balls that are close in size to a golf ball which is 1.68" in diameter. My steel balls are 1.5" but you could also use 1.75" balls. You can get these on Amazon.

My version uses your HOC gauge to measure the depth of the impression on your green. Don't tell your mechanic.

Instead of a washer I used an old bedknife that is the same thickness as the little knob below the HOC gauge.

center the hole with paint over the indent

Find a bedknife that is a similar thickness to the tab on the bottom of your gauge.
In order to get consistent data you need to drop the balls from a constant height. I use a flag stick (assuming all of your flags are the same height). I drop the balls from the bottom of the flag because no one else on my crew can reach the top!

This version requires you push down on the gauge to test the depth. This obviously introduces some error so be as careful as possible to not push too hard.

I take a few measurements then log them in my firmness tester spreadsheet found here.

I've been asked a lot about how much the balls should weigh. I don't think it matters much as long as all your balls are the same mass and size. The only reason to have a standardized ball would be to compare to other courses which isn't what this is for.

In time I expect to build an understanding of what this data means. What is firm and what is soft and if it's something that I care about enough to measure or invest further in one of the fancy units.

For now I've pulled this data into my maintenance HUD to see how important this data really is.

If you like my blog and want to support what I do you can support me on Patreon or paypal. Thanks!

If you like my blog and want to support what I do you can support me on Patreon or paypal. Thanks!