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Discussion in 'Organic Lawn Care' started by Smallaxe, Jun 25, 2009.

  1. Smallaxe

    Smallaxe LawnSite Fanatic
    Posts: 10,081

    "The most important property affecting desorption, according to their study, was the extent of P saturation, but the authors warned that further research was needed to test the relationship between desorbable P and P transfer into leaching and runoff."

    This is from the last article on the link list. It is a statement that makes sense. This is where farmers and LCOs have been acting unknowingly about their fertilizers. We have not worked with the natural order but have replaced the natural order.

    Ferts don't work beyond CEC, and yet we think it is the fert's problem or we need to add a little more. As a result we have an outside mined P going into a soil that is already saturated, just not according to the lab results. :dizzy:

    I still believe that there is a stable level of P in a soil that will no longer move about. Of course this is a balancing act for harvestted crops. However, making lawns a harvested crop is just nonsense.
  2. Kiril

    Kiril LawnSite Fanatic
    Posts: 18,308

    IMO it all hinges on not expecting more from your land than it can give naturally.
    When you expect unnatural production from your land, your inputs increase and your bank account decreases.

    While in many basic ways managing landscapes is similar to Ag, the end goals are NOT the same.
  3. muddstopper

    muddstopper LawnSite Silver Member
    Posts: 2,342

    There are about a dozen different methods for testing P in the soil. With each test you also have the multiple different ways testers interpet these test. You can take one soil sample and split it evenly amoung all the different testing methods and all the different testing facilities, and you will lucky if you get even two that will show the same results. For this reason, I pay very little attention to any publicized number as being to little or to much. 10lbs or 50lbs or even 100lb numbers can result from the same soil sample tested using different testing methods. If you want the numbers to read low, use a water soluible test, if you want the numbers to read high, use a acid soluible test. If your a fertilizer company wanting to sell P, you will chose the water soluible test for determining P levels and the acid test formulas for determining how much P to sell your customers. That way you can sell P to someong that doesnt really need it. And this is a actual part of the problem with the stinky water syndrome, and where a large part of the p found in the waterways is comeing from. Big business screwing the customers at the publics expense.

    Every soil has a certain capacity for absorbing Phos. Once that level is achieved, the rest will flow from the soil. Yes it can endup in our ground water, but the usual polluting source is not from P that has cycled thru our soil, but rather from runoff and erosion that is flowing down our ditches, drain pipes, and streets..
  4. muddstopper

    muddstopper LawnSite Silver Member
    Posts: 2,342

    Most sensible response in this thread.
  5. JDUtah

    JDUtah LawnSite Silver Member
    from UT
    Posts: 2,636

    uh oh! Looks like I gotta stop applying compost then!

    JK. Muahahaha ;)
  6. Smallaxe

    Smallaxe LawnSite Fanatic
    Posts: 10,081

    So in view of what was said here.

    A general rule of thumb in regards to P, could be, :

    "Apply only as a last resort, when the plants show a deficiency rather than a 'soil test'. Otherwise build the CEC and help promote the growth of AM Fungi - first..."
  7. Kiril

    Kiril LawnSite Fanatic
    Posts: 18,308

    For me, that is the general rule of thumb for all nutrients ..... "Apply only as a last resort".
  8. nc-jrock

    nc-jrock LawnSite Member
    from NC
    Posts: 133

    Could you guys tell me what CEC stands for ?

    Thanks in advance.
  9. muddstopper

    muddstopper LawnSite Silver Member
    Posts: 2,342

  10. Smallaxe

    Smallaxe LawnSite Fanatic
    Posts: 10,081

    Cation Exchange Capacity. Simply put it is where a nutrient molecule latches onto a particle and the root is able to extract it for use. How many places for a molecule to latch onto defines its capacity.

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