Saturday, 14 September 2019

Turfgrass Speedo is Better Than I Thought



Last fall I came up with the idea of comparing actual growth to ideal growth to get a ratio of growth. I called this tool the turfgrass speedo.

Ideal growth was calculated using the growth potential formula on my weather modeler spreadsheet and would use the ideal monthly nitrogen rate to determine how much grass should be harvested based on actual conditions not just a date on the calendar. The idea was to growth the grass at the right speed, not just as slow as possible. Growing the grass too slow is worse than growing it too fast. When you grow it too fast you get excess thatch and have to mow it more but when you grow it too slow it can't handle the traffic or stress of any kind really.

I had made all sorts of observations about growth in the past and the model seemed good. This winter I started a new job at a new course and was excited to see how the model worked at a different course.

For the first 5 months of the year the model was working perfectly. It suggested growth was too high when it was actually too high and during March through May it was predicting growth almost perfectly.


When June hit the growth rates seemed to be OK but the speedo suggested that growth was too low for the weather we werre having. I wondered if the model wasn't that good because the greens were awesome. Green speeds were way up and golfers were happy.

I noticed the first incidence of anthracnose on June 25th and we sprayed for it shortly afterwards. I wasn't going to get fancy my first year at a new course.

Anthracnose came on hard in late June, got better in July, but again, got much worse in August.
The disease slowly progressed in July and we increased nitrogen rates to help manage the disease as this is usually the most effective way of managing anthracnose. As July was quite cool, growth rates were down and nutrient demand was also low. The only problem was that in August the disease got worse and the speedo again suggested that growth rates were way below where they should be. The charts showing nitrogen applied vs nitrogen removed via clippings also showed that we weren't getting very good return on our fertilizer applications. I would have expected much more growth for the amount of fertilizer I had applied.

I would remove about 80% of the nitrogen that I applied in the clippings at Pender Harbour

My new course wasn't getting a very good clipping return, only 20%
Maybe the models were wrong I thought.

So we kept on fertilizing and the disease kept on getting worse. The bentgrass that was seeded a few years ago was very happy, but the predominantly poa greens were not doing so good. The anthracnose was bad and we couldn't get the growth we needed and as we all know, fungicides aren't the ideal solution for diseases like anthracnose.

I had had enough so applied a very heavy nitrogen application to the worst greens to try and push recovery. They greened up but growth didn't spike at all. I then applied a phosphite product to the greens and the day after they looked the worst I had seen all year. BINGO!

It's common knowledge (or should be if you are using these products) that applying phosphite to phosphorus deficient turf will make that deficiency worse. Our soils tests were high in phosphorus but what my observations and the data were suggesting is that something was limiting growth and now I knew that it was probably phosphorus. I applied some fertilizer containing phosphorus and the day after the greens looked the best they had looked in more than a month.

Severely affected green is glowing the day after a phosphorus application
Growth rates have climbed substantially and the models are happy once again. We are still on the low side of the ideal growth and have to push recovery so the plan is to continue to push growth until we are on the upper side of the growth ratio.

Overall growth rates have been too low this year but have improved in the past week to ideal levels.
Why wasn't the poa getting enough P? I don't know for sure but the roots were pretty short and the maybe they weren't as deep as the soil tests in the past were taken from. This would also explain why I had OK growth when temperatures were low but as soon as the demand went up, the grass ran out. We had a rough winter and maybe that was why? The spring was super dry and hot so maybe that's why?

We are getting a much better nitrogen return this past week as conditions improve.

This was a first for me. Normally growth rates were too high in the summer months and I always got an almost immediate response to nitrogen fertilizer.

So lesson learned and now I know that the models are probably better than I think. Using clipping volume and weather data can show you when you are within normal conditions and could probably give you an early warning that something isn't right. It's difficult to judge what amount of growth is appropriate for the ever changing weather we experience so models like this can make fertilizer decisions easier and can probably point out potential issues sooner.

My previous course had the opposite problem. The newly established and deeply rooted bentgrass would grow out of control in the summer as it had so many nutrients available the the poa NEVER had access to in the soil.

It's super easy and inexpensive to simply apply a complete fertilizer blend each week especially during the stressful summer months. When growth rates drop off maybe rely more on what the soil can provide. Or, if you have more bentgrass, use this phenomenon to kill poa. Unfortunately for me, there is a lot more poa than I would like here so that kind of craziness needs to wait a few more years.






Wednesday, 8 May 2019

1 Week Impression of the Husqvarna Automower 450x on a Golf Course Fairway

Last week we (fellow superintendent) got the first automower in Western Canada to be used on a golf course (from what we can tell).



I've talked a lot about robot mowers recently and how they could potentially benefit golf with mower savings of up to 50% but more realistically 20-30%.

Micah Woods also recently wrote about how they are more energy efficient and can help reduce GHG emissions even when the electricity comes from coal.

So in theory these machines could be a game changer for golf and turfgrass management. They are also the best solution to transitioning off fossil fuels without having to spend a fortune on big electric mowers.

Even though these mowers have been used for quite some time in golf, there is little information other than a few youtube videos and my blog posts. So we decided to give one a go and see for ourselves how it would work and share the experience.



The superintendent who is testing out the mower set it up on one of his fairways. We set the HOC down as low as the machine would go to 2cm. Modifying the HOC lower would not be difficult with a few shims but as this is only a demo machine, we cannot modify it.

Setup was very easy with the wire being strung around the perimeter and fastened to the turf with plastic pegs. For a permanent installation I would install the wire under a narrow layer of sod to protect it from golf club swings. Make sure you lay it where you want it otherwise you will be doomed to ugly cleanup cuts for ever!
Cleanup cut is rough at first but once the machine follows wire back to charge it cleans up nice.



The first thing we did after opening the box was take it apart!

The blades are small razor blades that are double-sided. The machine can rotate either way to maximize blade life.

Modifying this to cut lower would not be difficult.

After that you just let the machine go and to be honest, it's not that impressive, but in a good way. To see this little machine bounce around the area is not very fantastic,  but after a week I returned to see that the grass looked exactly the same as when I last saw the machine. Whoa, it works!

Not bad for no human input after one week of good spring growth.
The cleanup cuts were impressive as the machine uses the perimeter wire to find its was back to the charging station.

When someone touches the machine it lets out a super annoying alarm and instantly notifies the owner via text message.



Turf quality is OK. I won't say it's GREAT because it isn't. At only 2cm the height just isn't low enough for premium fairway turfgrass in my opinion although it's surprising good for being so high. The logistics of how these machines work are very interesting. They aren't like conventional mowers where there is a certain capacity per hour. These mowers have a total capacity period, no time limit.

The way they work is they bounce around the area for about 20 hours a day. The rest of the time they are charging themselves on the docking station. So during that 20 hours, they mow almost all of the area at least once, and a lot of the area more that once. When you think of it, the area down the middle will have the machine pass over it multiple times each day as it zig zags down the fairway.

You see on your phone where your robot has been. 

We can do a little math here. It mows at about 3000 meters per hour. The blade disk is 0.24 m wide. That means it cuts about 720m^2 per hour. It mows 20 hours a day so it cuts about 14,400m^2 per day. The capacity of the mower is only 5000m^2 a day so how does that work? According to this math it could cut 3x the area.

Because the mower doesn't work like conventional mowers that only cut grass once, it covers a lot of the areas a few times a day.  I estimate it to mow a given area about 3-5x a day. There are few courses I know of that cut that often! There area  few reasons they do this. 

Simplicity: It is way easier to have a mower just "randomly" drive around than drive super specific paths with little overlap. This is why the conventional robot mowers you see are so expensive and have such a low capacity. They are super complicated machines. The automowers are super simple machines.

Efficiency: It takes a lot of power to cut long grass. This is why our big rotary rough mowers have such big engines and require so much fuel. The costs goes up further with tier 4 emission regulations for high horsepower engines. The robots need to be super energy efficient to be fully electric, small, and affordable. Therefore they cut the grass super frequently to only take a little grass off at a time. This allows them to maintain a relatively large area almost constantly with little power required. It also allows them to use cheaper and smaller batteries which are still quite expensive.

As we aren't paying a person to operate this mower, the time it takes is irrelevant. The machine is almost silent and we have had no comments from golfers over the past week. As I said earlier, these machines are not very impressive at first glance. They just trundle along.


It just happens that for a lot of courses the capacity of this mower will be the size of the average fairway.


These mowers have a very small wheel base similar to that of a reel type mower except the blade disk is on an angle so the only part that cuts is directly between the front wheels. Our test site is a fairway that is very bumpy and this machine scalped long turf in the BOTTOM of a few dips that the conventional mowers couldn't reach. No scalping on the tops so far.

scalped turf on the BOTTOM of a dip that reel mowers couldn't cut.
The way height of cut works with these mowers is also different than conventional mowers. 

You might set your HOC at 12 mm with a conventional mower and go cut the grass. Immediately after mowing that is about the height of cut you get, but as time goes on, it gets higher and higher. How high is the grass when you mow it again? If you figure this out you can calculate what your average HOC is with a conventional mower because that's all it is. An average over time.

With the automower the HOC is the HOC. As discussed above, most of the area gets cut multiple times a day so the HOC stays the same. This allows you to maintain a similar average HOC as conventional mowers with a higher bench height setting. It's weird to think about but that's how it works. Also, no clippings!


Automower on the left, unmown middle, conventional reel mower on right.
As I mentioned, the turf quality wasn't what I would expect on premium turfgrass. Obviously the height needs to go down.

There is also no striping so the grass grain really shows up and looks a bit mottled. This could be fixed with a weekly roll which would give you many more benefits to just mowing such as reduced disease, more consistent appearance, and a quick and cheap process.

We are going to test this machine out for a few more weeks on the fairway and will then move it to some high profile rough.

This now has me thinking of how to optimize the area that each of these mowers can cover. Below is an image I put together with theoretical areas each mower would maintain. When doing this you want to have as many different areas to intersect at one given location to minimize the amount of power wire you need to install for the charging stations. If you have satellite irrigation controllers you already have the power wire installed so what are you waiting for?


These machines are ready for golf out of the box. While not for premium turf, they would be more than adequate for most courses and with a few modifications would be even better. They offer huge advantages to an industry facing labor shortages, rising mower costs and rising fuel costs. With these mowers we can allocate our staff to do the important jobs we used to do before the golf industry entered the recent decline.