Friday, 30 June 2017

Starting to figure this soil balance thing out.

There are lots of people who talk about soil balance and the biology in the soil. This is something that is really hard to quantify but as I start to measure yield and compare the growth rates to disease rates, it is starting to make sense to me.

Something that has always bothered me is people selling products that claim to achieve that balance. As we know so little about soil biology, how can any one product really make that big of a difference? To my simple brain, it just doesn't make sense.

One of my main struggles over the years has been trying to understand turfgrass disease and how we can prevent it and the need for corrective traditional pesticides. I have made great progress in trying to reduce their use on my course. I have tried to cut through the bullshit out there and focus on what really matters. There is so much dogma surrounding turfgrass disease and it is easy to get confused about what really makes a difference in making reductions in pesticide use.

One of the most enlightening things for me has been measuring clipping yield. It wasn't until recently where I had wildly differing yields and also wildly differing disease rates that it started to become more clear to me.

Looking back on my growth rates over the past year and comparing it to when fungicide applications were made it has been interesting.

I have been able to grow grass without fungicide every month so far except September. It's a hell of a month coming out of the summer stress and transitioning into cooler weather and fusarium season. Last year I needed 2 fungicide applications to control fusarium in September. Based on the following growth rates can you guess when?

I applied a fungicide on both the 4th and 27th of September last year and these dates both coincide with huge spikes in the growth rates. I saw the same thing this spring.

This brings me back to soil biology and balance.

These huge spikes in growth were most likely the result of conditions in the soil being ideal for mineralization of nutrients. Essentially the biology in the soil is going wild! I highly doubt that any miracle product could control the biology in the soil or achieve balance during these periods of high mineralization and plant growth and if anything, during these times, we want less biological activity!

Active Fusarium in June on a high nitrogen green.

I wonder how this could impact disease in the plants but have no way of knowing this. Could it be the release of nutrients in the soil that makes the plant more susceptible to disease as we know that higher nitrogen and potassium rates can lead to increased fusarium? Or is it the same conditions that lead to the increased mineralization that lead to a population boom of the bad microbes? I don't know if there's an answer to this question.

I also don't think it matters. Essentially we want to be aware of this phenomenon and try to manage it if possible.

Can we manage soil mineralization?

I also don't know the answer to that but maybe the negative impacts of it could be lessened with cultural practices (or lack of cultural practices) like needle tine aerification or strategic irrigation. I had an interesting talk from a European Agronomist last year where he had seen disease brought on by aerification. Is there such a thing as too much soil oxygen at some times? Could aerification before weather events that lead to high mineralization reduce this phenomenon. Could aerification after or during these events make it worse?

I have often struggled to know why some greens got disease worse than others and I think it has to do with the soil, and the activity of the soil biology and how this varies across my property. As growth rates vary across the property quite a bit on any given day I wonder if it's even worth trying.

But if you know me, I'm going to try.

Wednesday, 28 June 2017

Differences and similarities in growth rates

It has now been just over 2 weeks since I started measuring clipping yields on individual greens.

Firstly, it's worth noting that we have not recorded any increase in time that it takes to cut the greens in the morning. Yes, it's only been 6 mows compared to thousands in our database but it's insignificant. Not having time simply isn't an excuse to not do this.

As my damaged greens recover they have had higher growth rates due to the increased fertilizer that was applied to try and speed the recovery. My undamaged greens got their regular fertilizer rates based on the growth potential and are growing much slower.

In an earlier post I wondered how I would transition the high growth to low growth. What I have done is simply not apply nitrogen to the greens that are growing too fast. This has been the result.

As you can see the damaged greens are still growing quite a bit faster than the undamaged but now that the undamaged greens are the only ones receiving supplemental fertilizer, their growth rate is trending higher (as it should be this time of year) and the damaged greens growth rate is trending downward. I estimate that at this rate of convergence that they should have similar growth rates in about 2 week's time. It will be interesting to see how they react differently during periods of high mineralization as I suspect that the dead organic matter from all that poa might be elevated on those greens and could lead to excessive growth.

Another thing I find interesting is how the two lines, while different, are similar. When one goes up, so does the other. So even though we have two different growth rates based on fertilizer, they are both impacted similarly to the other things that impact growth like temperature, light, water and snake oil. 😜

Thursday, 22 June 2017

Stimp vs Yield

I never thought having dead greens could be so interesting. Extreme circumstances like having to grow in new greens has given me completely different growth rates across my greens. Obviously this isn't great for consistency but it is great for learning stuff and maybe improving for the future. Right now I have highly variable growth rates on my various greens and this can be used to my advantage to see how this different growth rate impacts playability.

This week I decided to compare clipping yield to green speed. It's a limited data set and I will continue to collect it into the future to get better data but the first set of results is pretty interesting but not entirely surprising. Please remember that there are a million variables involved here. Grass type, cultural practices, height of cut, roll or no roll all can impact the ball roll. I think this will have to be measured on each course and for each cultural practice to figure out what is best for your course. Also note that this is preliminary data and could obviously be more thorough but I'm only one guy who has a course to run, this isn't a research farm!

So from this data you might say that the higher the yield, the slower the greens.

But what if you double cut?

Yield goes up, speed goes up or stays the same. hmm.

Maybe we need to look at it slightly differently. What if instead of total yield on a green, we look at it as yield per cut?

So I decided to test this on my greens with a higher yield. I double cut holes 2, 3, and 5 as they had the highest yield today.

1st cut
2nd cut
Percent Change
Average Change-58.40%7.35%

As you can see, on the second cut the yield-per-cut went down by almost 60% but the green speed when up by 7.35%

Nothing new here really, except now that I am monitoring yield on each individual green, I can optimize green speeds based off this data. Lets look at today's data and see how it statistically changes our conditions.

Hole1st cut yield1st cut stimp2nd cut yieldtotal 2nd cut yield2nd cut stimp

After mowing the high yield greens a second time the coefficient of variation (Cv) of the yield went up overall, but it went down for stimp just as we would expect.

So how can we optimize green speed based off of clipping yield data?

Well, if we can get a low clipping yield Cv we can probably get a low stimp Cv.
By varying fertilizer rates on greens the yield Cv (single cut) is going in the right direction.
Still, nothing really that new here. It's just common sense.

What I do think is new is how we can use this data in the real world to ensure that we are producing the most consistent playing conditions from green to green, especially during times when growth rates are wildly variable like they are for me as we recover from winter damage.

I'm not hosting the US Open or any pro tourney for that matter so I don't have a dedicated crew to ensure that the greens are consistent every day. What I do have is one person who mows the greens and collects the clipping in the basket. It is almost no work to dump these clippings into a measuring pail and to write how much you got down. With this clipping yield I can have my staff automatically determine if a double cut is needed or not. Of course, as you can see from the data above, my green speeds with a single cut only aren't that variable for a public course. Most golfers here simply couldn't tell the difference. But for those special tournaments it could help us optimize our green speeds. I'm not the only one already doing this.

I can determine the optimal yield-per-cut and have my mower operators double cut a green if they get more than that yield. Ideally we would want all our greens to grow consistently but in the real world they might not 100% of the time. I also have a hunch that as green speeds increase well above our relatively slow speeds this week, the variance will increase with a smaller yield Cv. So yield could be more important the faster your greens get. I'm not 100% about this because my greens aren't fast.

So what is the optimal clipping yield?

I think that is highly variable for each of the variables that you apply to the grass that could impact green speed so each course will be different.

I can take all my yield vs stimp data and sort it by yield and compare green speeds over a certain yield vs green speeds below a certain yield.

If we compare green speeds above and below 4L/100m^2 we get

Optimum Yield4
Above OptimumBelow OptimumDifference

Change that to 3L

Optimum Yield3
Above OptimumBelow OptimumDifference

Or 2L

Optimum Yield2
Above OptimumBelow OptimumDifference

I don't have any data below that's as far as I can go...for now. For Paul Robertson at the Victoria Golf Club, they have found their optimum is 0.6L/100m^2.
As you can see, the lower the yield, greater the difference in green speed on my greens. So if I want to get the maximum green speed (and consistency between greens) with my management practices and mowing alone (no rolling but why would you not roll?) I need to get less than 2L of grass per 100m^2. I could also make it easy for them and would give them a yield for each green that would take the area of the green into account.

This leaves me to wonder if it is better to find consistency in green speed with a roller or with a mower? I have seen in pro tournaments that they roll different amounts to get that consistency but I wonder how that impacts consistency over the long term. So many questions and even though they really aren't applicable to real life for most courses (because who NEEDS green speed variation around 2-3") I think that if you know the various impacts of different practices you can optimize your greens with minimal effort. I'm not only concerned with optimal green speeds, I have to balance budget, labor resources, and impacts on disease and the environment but by knowing I can try to achieve this with mowing if necessary, or controlling the growth rates ideally.

I plan on dropping the HOC on greens this week so it will be interesting to see how these relationships change as the HOC drops.