[HomerGuy]

Hi All,

First of all, I wanted to say thank you to @g-man for the info on soil testing.

I knew there was a likely chance that I had alkaline soils, so I requested the SW1 test from Waypoint Analytical in Memphis. Cost was $26.50. They received my sample on Thursday and by Friday afternoon I had the results. Very impressive.

Here are the results. Frankly, I'm amazed that my lawn looks as good as it does given these test results. Looks like I need to get shopping for some high phosphorus & potassium fertilizers.



A few questions/comments:
1. Ouch....that soil pH is not so bueno. I need to start reading up on lowering pH.
2. Given the pH, I'm guessing that any nitrogen that I apply should be AMS and not urea? I'm guessing the AMS won't do much to help the pH, but every little bit helps?
3. Phosphorus was measured twice with different results. Why was that?
4. The recommendations are interesting. I can see why it is recommended to send a soil sample to a lab close by, but I can adapt them to my climate.

 

[Ridgerunner]

I'm going to kibitz. The SW1 should have included the Olsen P test. It appears they did a Bray P1 instead. I suggest that you call them Monday and get that straightened out. Forget trying to lower a pH 7.9 soil, but yes, regular apps of AS should help counter the effects of high pH by lowering solution pH and helping make nutrients more available.

 

[HomerGuy]

I'm going to kibitz. The SW1 should have included the Olsen P test. It appears they did a Bray P1 instead. I suggest that you call them Monday and get that straightened out.

How did you determine that? I see P was measured using the B1 method (I'm guessing that means Bray) and once as M3 (guessing Mehlich 3). Is that it? I would have never noticed that, nice catch!

And thank you @Ridgerunner . Your soil test thread is a goldmine of info. I'm still trying to digest it all.

 

[g-man]

Yes, AS will be your friend. You will also need some FAS (normally around now), not just for green up but for actual chlorosis. (trees and lawn).

 

[Ridgerunner]

How did you determine that? I see P was measured using the B1 method (I'm guessing that means Bray) and once as M3 (guessing Mehlich 3).

Yep.
Olsen was developed because the other methods underestimate/under-reported P in high pH soils. If they had used Olsen, you would expect the P results to have been somewhat higher than the M3 results. They are lower, that's when I saw B1, Bray P1 being a weaker extraction method would result in lower reported values than M3. All of which is consistent in your reported numbers.

 

[g-man]

My two cents, even if the Olsen is double of the m3 P, it will still be 26ppm and I consider that low. I would apply P. I'm interested in what they say in regards to the Bray and Olsen.

 

[Ridgerunner]

even if the Olsen is double of the m3 P, it will still be 26ppm and I consider that low.

What is your rational for that determination @g-man? Are you basing that on a published range for Olsen sufficiency levels or something else?

 

[HomerGuy]

Yes, AS will be your friend. You will also need some FAS (normally around now), not just for green up but for actual chlorosis. (trees and lawn).

Just ordered 30 lbs of iron sulfate from Kelp4Less.

How do I apply FAS to trees? Is that a foliar application just like turf?

 

[g-man]

There is a correlation (r=0.81) between m3 p and Olsen P when the pH is high. An Olsen value of 20 is around an M3P of 50. The test had a M3P of 13ppm, than would be an Olsen of around 5ppm (below Olsen 12ppm).

http://www.agronext.iastate.edu/soilfertility/info/ComparisonofMehlich-3OlsenandBray-P1Procedures.pdf

Page 98, 3rd chart from the right.

 

[g-man]

@HomerGuy yes foliar just like the turf, but it is hard with tall trees or those close to the house. I just tried a eddha iron for the soil (works in high pH). It is a lot more expensive and I just applied it last week.

 

[HomerGuy]

Back from vacation and got around to emailing Waypoint about the Olsen P.

Apparently they did perform the Olsen P test. They pointed out the "key" at the bottom of the test results (which I didn't even see and subsequently cropped out), in which "BI = Olsen P".

I was very impressed how responsive Waypoint was. Not only did they run the test and send the results super fast, but they also responded to my inquiry quickly as well.

 

[Ridgerunner]

Back from vacation and got around to emailing Waypoint about the Olsen P.

Apparently they did perform the Olsen P test. They pointed out the "key" at the bottom of the test results (which I didn't even see and subsequently cropped out), in which "BI = Olsen P".

I was very impressed how responsive Waypoint was. Not only did they run the test and send the results super fast, but they also responded to my inquiry quickly as well.

@g-man was dead on. :thumbup: I wasn't aware of how correlated M3P and OlsenP were. Thanks g-man.

 

[g-man]

Great info here. So, you should use AS, apply P and K. I would mulch my clippings and try to apply some iron.

Ridgerunner, it was Oscar (from Waypoint) that pointed me to look more into this. It seems that M3 is good enough for all pH. I'm not there yet mainly since it is only $10 more.

 

[HomerGuy]

Question for the soil gurus......

I am game planning my fertilizer applications for the remainder of the year, trying to meet the recommended amounts of NPK per the Waypoint test. My question is, what are the limits per application for P and K per thousand? I have heard to keep Nitrogen applications to less than 1 Lb per thousand, but are there any guidelines for P & K?

 

[Ridgerunner]

There are no known toxicity levels for P and K. However, both can adversely affect the turf's relationship with other nutrients. P can tie up many micro-nutrients making them less available and K has an antagonistic relationship with Mg, interfering with the turf's use of Mg (Mg is an important component for photosynthesis).
Seeing as the plant can only use only so much of any nutrient anyway, there is no advantage to flooding the soil with any nutrient other than saving time (being too lazy to make multiple applications). Then there is also the risks to the environment due to erosion. Best practice is to apply no more than 1#/M of P2O5 per month (every 60 days would be better) and 1#/M of K2O per month. Yes, people have applied more without reported ill results, but other than the time savings, there is no advantage to the turf in doing so and there are the possible downsides.