Nutrient availability versus total sampled levels?

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Nutrient availability versus total sampled levels?

Post by Green » June 15th, 2018, 11:57 pm

Andy, for the tests that Logan does, and the interpretations using your method, how do you differentiate between total soil levels of something like P, K, or Ca, versus the actually plant available levels? I keep reading articles that say that much of the nutrient reserves in soil may not be actually available because they might be bound to other things. But surely your analysis method in combination with Logan's testing tries to predict what's actually available, and optimize availability over the long-term.

Can you shed a little more light on how big a deal this topic is in lawn care?

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Re: Nutrient availability versus total sampled levels?

Post by andy10917 » June 16th, 2018, 12:46 am

It's way too complex for a mid-season topic. I could go on for quite a while.

Save this one for November, when the site is quiet. We'll discuss it in detail...

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Re: Nutrient availability versus total sampled levels?

Post by Green » December 1st, 2018, 2:05 am

Andy,

Bringing this back so I can learn some of the background over the coming months. Feel free to jump in whenever you're ready...

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Re: Nutrient availability versus total sampled levels?

Post by andy10917 » December 1st, 2018, 10:01 am

Good idea! I'm in - and it's a really good time to explain some of the "philosophy" that I use in the overall recommendations that I create. You may be disappointed in that there aren't strict formulas that you can execute yourself - my approach is I call "HELM", which is my last initial (first letter of my last name plus "Empirical Level Management"). That means that I don't blindly look at numbers on the Logan tests and automatically translate them into recommendations. Why? Because it doesn't work. What DOES work is listening to what happens when we apply nutrients and seeing how the turfgrass responds. For my own lawn I measure the presence of sugars being produced by the grass plants as an indication of whether the lawn is responding or not.

This is going to be a long thread - I hope that's what you're looking for, and not easy-peasy quick formulas to apply...

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Re: Nutrient availability versus total sampled levels?

Post by Green » December 1st, 2018, 7:03 pm

andy10917 wrote:
December 1st, 2018, 10:01 am
Good idea! I'm in -
......
This is going to be a long thread - I hope that's what you're looking for, and not easy-peasy quick formulas to apply...
Yes, that's the idea. Go as far in depth as you'd like, as long as it's presented in a logical way that builds on previous concepts. Also, feel free to mention the sources you're most interested in that helped you learn and eventually create your own method...whatever you want to do, is fine with me. As much as you want to talk about, and I'll read it.

Now, just so you know...I may not generate a lot of responses initially or at regular intervals after you make each post. Feel free to keep going whenever you think of something that makes sense to post. That said, I WILL be reading and re-reading and processing what you're writing on a regular basis, even if I don't reply immediately all the time.

That said, I'll definitely have lots of follow-up questions from time-to-time after I think carefully about some of the things you present. But there will probabably be intervals of nothing from me at times while I'm processing, looking up more info on certain ideas, or seeking definitions, etc.


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Re: Nutrient availability versus total sampled levels?

Post by Spacklerstyle » February 10th, 2019, 3:37 pm

Subscribed...

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Re: Nutrient availability versus total sampled levels?

Post by pintail45 » February 12th, 2019, 5:22 pm

Spacklerstyle wrote:
February 10th, 2019, 3:37 pm
Subscribed...
x2

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Re: Nutrient availability versus total sampled levels?

Post by Green » January 29th, 2020, 7:13 pm

Hey Andy...any time for this topic over Winter 2020? I'm still interested in your take on nutrient availability versus sampled levels.

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Re: Nutrient availability versus total sampled levels?

Post by andy10917 » January 29th, 2020, 10:15 pm

There are several things I pay attention to,and some of the items are things that I can never see from your lawn/soil. I have to extrapolate what I've seen in my own lawn/soil and guess that in your lawn under similar scenarios, the same things might happen. Sad to say, but whether your lawn and soil succeeds or not is just another data point that helps me to fine-tune my estimations and guidance. Over 15 years of practice, most have gotten pretty tuned-in.

The best indicator is Brix. People laugh, but the evidence says that it works. It's actually the reverse-case of the Law of the Minimum. The Law of the Minimum says that you will never get more production than the scarcest nutrient will allow -- sort of a version of the "weakest link in a chain". When the scarcest nutrient is gone, the plant (including grass) just won't get producing more tissue and sugars.

Now, there is an exception to the rule: Nitrogen. So, why don't we just pour on tons of Nitrogen instead of a more-balanced formulation? Because it's a mirage - the plant is FORCED to grow even though it doesn't have all the nutrient components. Brix actually falls as the plant grows, and that amounts to stress. And stress means an increased tendency for disease to develop.

The other big component that I watch is the ratio of one nutrient to another. A couple of examples are the Calciun:Magnesium ratio, the Iron:Manganese ratio, and the Calcium:Boron ratio. All are important, but there are numerous others of varying importance.

Also, there is Mulder's Chart. Some nutrients have antagonistic relationships with others, and some have synergistic relationships.

Lastly, there are relationships of nutrients to other measures like pH. An example is Iron. Iron is very available at moderately acidic scenarios, but you can have all the Iron in the world and it means nothing at a pH strongly on the alkaline side. Even at a pH of 7.2 or so, the availability is falling like a rock.

So much for the first post...

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Re: Nutrient availability versus total sampled levels?

Post by Green » February 2nd, 2020, 6:47 pm

Andy,

Interesting. How is Brix related or different from carbohydrate storage? I was reading that it's more than just sugars, but can also be proteins, etc. Does it give you a good approximation of the carbohydrate levels? Have you tested it to see how Nitrogen affects it? I would guess the Brix levels would tend to drop after a Nitrogen application, due to the plant expending energy to process the N. But then I'd expect to see it increase as the Nitrogen helps the plant to photosynthesize. Have you ever tested it before and after a winterizing Nitrogen drop?

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