[NAFEX] leachy phosphorous

Mark Angermayer hangermayer at isp.com
Thu Jun 25 15:32:05 EDT 2009


Rivka wrote:

"c) during just about all of the evolutionary history of these plants humans were not applying P annually to supply them: 
therefore, it's got to be made available by some process not involving human intervention."

That may be true, but evolution typically produces very low yields with the exclusive goal of survival of individual species.  The yields nowadays of many crops remove far more P than can be supplied without the aid of human intervention. 

Mark
KS


  ----- Original Message ----- 
  From: Road's End Farm 
  To: North American Fruit Explorers 
  Sent: Thursday, June 25, 2009 8:42 AM
  Subject: Re: [NAFEX] leachy phosphorous


  Actually, since 
  a) it's an essential plant nutrient 
  b) there are lots of plants in existence that need it 
  c) during just about all of the evolutionary history of these plants humans were not applying P annually to supply them: 
  therefore, it's got to be made available by some process not involving human intervention. It's possible, of course, that this process may be damaged/nonfunctional in some cultivated fields, especially if it involves bacteria or fungi.

  I think I did post earlier about the capability of some plants to put P into forms usable by others.

  --Rivka
  Finger Lakes NY; zone 5 mostly

  On Jun 20, 2009, at 7:59 AM, Richard Harrison wrote:


    My county agents office has always taught that P was rather immobile. Now that doesn;t say anything about whether it is available for plant uptake or not. If very immobile, I would question its availability to plants to absorb it.
                                                  Richard

    --- On Fri, 6/19/09, Alan Haigh wrote:


      From: Alan Haigh 
      Subject: [NAFEX] leachy phosphorous
      To: nafex
      Date: Friday, June 19, 2009, 8:59 PM

      Ok, the contradictions on this site to my understanding of phosphorous was starting to bug me.  I was beginning to think my memory was going so I went to my book shelf and grabbed Brady's "The Nature and Property of Soils" to look up phoshorus.  I quickly found this statement "When soluble forms (of phosphorous) such as those found in manures and fertilizers are added to soils they are fixed (bonded tightly to soil solids in a form generally unavailable to plants) or are changed to unavailable forms and in time react further to become highly insoluble forms".  He goes on to say that "phosphate is essentially an immobile nutrient".
       
      Does anyone have some actual information that contradicts this, based on scientific understanding?  Or am I just not understanding what I'm reading?






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