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  #41  
Old 09-13-2012, 02:37 PM
BTC BTC is offline
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I believe everything leaches, but nitrogen much more so than the other macro nutrients.
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  #42  
Old 09-13-2012, 03:27 PM
turfmd101 turfmd101 is offline
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Most Fl palms show P deficiency. A pretty yellow - orange.
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  #43  
Old 09-13-2012, 03:30 PM
turfmd101 turfmd101 is offline
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  #44  
Old 09-13-2012, 04:47 PM
Skipster Skipster is online now
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Quote:
Originally Posted by Kiril View Post
I forgot nothing skip and there is no "kind of" about it

We'll see about that.

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Errr Skip, when P become fixed to select cations it precipitates out of solution as a compound with variable solubility ... some of which may become part of the active pool, some part of the fixed pool. This has nothing to do with the CEC.

From Chapter 5 Phosphorus from Soil Fertility and Fertilizers (7th ed.) by Havlin, Beaton, Tisdale, and Nelson:

"When H2PO4- is bonded through one Al-O-P bond, the H2PO4- is considered labile and can be desorbed from the mineral surface to the soil solution. H2PO4- bonds to Al, which is bonded to the cation exchange site. In acid soils, P adsorption also readily occurs on the edges of clay minerals. In alkaline soils, H2PO4- bonds to Ca or Mn and remains part of the labile pool on the surface of soil minerals.

Only at excessively high P concentrations do these compounds precipitate."


Sorry. Again, the textbook says that P bonds to elements on the cation exchange sites and only precipitates when P concentrations are excessively high.

That's why I linked it with CEC -- most guys on this board understand CEC and P bonds to elements that are on CE sites. More CEC = more opportunities for P to bond. Less CEC = less opportunities for P to bond. I didn't think everyone else wanted a chemistry lesson, so I simplified it. Maybe it's not precise, but it gets the job done.

Perhaps you need to review your soil chemistry again.
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  #45  
Old 09-13-2012, 05:03 PM
turfmd101 turfmd101 is offline
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I believe the higher the cation-exchange capacity. The better the nutrient holding capacity. Clay is high. Sand is low. Then the CEC is based on % of sand to clay ratio. K also leave salt in the soil. Based on these factors. Salt from K can aid in minimizing certain weed species. Not a huge help.... but it will aid.
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  #46  
Old 09-13-2012, 06:05 PM
Smallaxe Smallaxe is offline
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OK thanks... I got the general idea... I was taken aback at first when K was mentioned as NOT leaching but I guess at the tune of 50 to 100 inches of water needed to move it 10 inches, for all practical purposes there's not much to worry about...
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Now that I know that clay's texture(platelets) has nothing to do with water infiltration, percolation, or drainage
,,, I wonder what does...
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  #47  
Old 09-14-2012, 10:37 AM
Kiril Kiril is offline
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Originally Posted by Skipster View Post
We'll see about that.




From Chapter 5 Phosphorus from Soil Fertility and Fertilizers (7th ed.) by Havlin, Beaton, Tisdale, and Nelson:

"When H2PO4- is bonded through one Al-O-P bond, the H2PO4- is considered labile and can be desorbed from the mineral surface to the soil solution. H2PO4- bonds to Al, which is bonded to the cation exchange site. In acid soils, P adsorption also readily occurs on the edges of clay minerals. In alkaline soils, H2PO4- bonds to Ca or Mn and remains part of the labile pool on the surface of soil minerals.

Only at excessively high P concentrations do these compounds precipitate."
And what does this have to do with the P bonding to the cation exchange sites per your statement? What you have quoted here is an incomplete explanation of pH dependent protonation/deprotonation reactions with O and OH groups on layer silicates and metal oxides and how solution P reacts with those groups. This in essence is anion exchange and it is not synonymous with K reactions with the cation exchange complex as you indicated. Nice try skip, you are indeed a world class back peddler.

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Sorry. Again, the textbook says that P bonds to elements on the cation exchange sites and only precipitates when P concentrations are excessively high.
It does not say P bonds to cation exchange sites which is what you stated. You can "skip" around that fact all day long, but in the end your statement is still incorrect.
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You are right to recognize that K is not as tightly held on cation exchange sites as P.
P is not held on cation exchange sites skip ..... end of discussion.

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That's why I linked it with CEC
And you did so incorrectly. If you can't speak with accuracy, don't speak at all.
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  #48  
Old 09-14-2012, 12:16 PM
Skipster Skipster is online now
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All my textbooks and all the soil P research I've found say the same thing -- soil P binds to ions that are attracted to CE sites. Thus, they are linked to CE sites such that fewer site means less P bonding and more sites means more P bonding. You have not refuted this.

Sure, P does not attract to CE sites by itself, but it DOES bond to ions that attract to CE sites. So, instead of trying to confuse everyone, I simplified the issue, and in doing so left out some info. However, that doesn't change the final message about P immobility in soils and you have provided no evidence to refute my conclusion.

I get that you're trying to nitpick so you can remain the king of some obscure internet message board, but there are no prizes for Message Board King here.
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  #49  
Old 09-15-2012, 09:29 AM
Kiril Kiril is offline
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Originally Posted by Skipster View Post
All my textbooks and all the soil P research I've found say the same thing -- soil P binds to ions that are attracted to CE sites. Thus, they are linked to CE sites such that fewer site means less P bonding and more sites means more P bonding. You have not refuted this.

Sure, P does not attract to CE sites by itself, but it DOES bond to ions that attract to CE sites. So, instead of trying to confuse everyone, I simplified the issue, and in doing so left out some info. However, that doesn't change the final message about P immobility in soils and you have provided no evidence to refute my conclusion.

I get that you're trying to nitpick so you can remain the king of some obscure internet message board, but there are no prizes for Message Board King here.
You confuse people by not providing the correct information. Either the information you present is correct, or it is not. Your information was not correct, so let me repeat myself.
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You are right to recognize that K is not as tightly held on cation exchange sites as P.
P is NOT held on cation exchange sites skip ..... end of discussion.
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  #50  
Old 09-15-2012, 10:09 AM
Skipster Skipster is online now
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So, now the correct information is out. I was not wrong when I said that soil P binds to ions that are attracted to CE sites.

Quote:
Originally Posted by Kiril View Post
Errr Skip, when P become fixed to select cations it precipitates out of solution as a compound with variable solubility
BTW, you should apologize for this statement, b/c the textbooks and research say that this is largely not true -- it only happens at excessively large P concentrations.

You're going to have to go back to school for soil chem, too.

Those who want to throw stones shouldn't live in glass houses.
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