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'N' Evaporation And Leaching

Discussion in 'Organic Lawn Care' started by Smallaxe, Jan 22, 2011.

  1. Smallaxe

    Smallaxe LawnSite Fanatic
    Messages: 10,082

    One thing I always like to have is, the documentation on, the 'loss of N' in synthetic granular or spray form, from the time it is applied, to the next time it is applied. [How much actually is lost, during that period.]

    A nice bit of research, that is, "Easy to Read', on the subject would be Great...

    Has anyone come across any articles, with sensible information, that could easily be relayed to a client?
  2. dKoester

    dKoester LawnSite Gold Member
    Messages: 3,341

  3. Smallaxe

    Smallaxe LawnSite Fanatic
    Messages: 10,082

    An excellent article, defining the natural processes of decaying OM into humates. It addresses the additional problem of 'too much' N which causes the loss of carbon available to the plant.
    This is the common denominator in the synthetic vs. natural recycling of nutrient discussion. A little technical...

    However, the recycling of carbon and nutrients by natural processes alone, do not accomplish the yeild or color of the grasses that people have come to expect.
    For that reason, additional N is required. Conventional wisdom to the client, with no technical understanding whatsoever...

    I believe that the additional N needn't be as excessive as it is to accomplish these ends, but I also have read that much of this unnecessary N is lost to the air and the water movement as well. Again technical, but simply described, if documented.

    My focus here is to determine the amount of N lost, AND the form in which it is lost, to decide just how much N could safely be added to the turf, as a 'Supplement' to what the microbes are already doing. This would give the client the idea of looking at NPK apps as a 'supplement' to what is already, a fertile soil...

    If I had something that demonstrated the loss of N, it would be simple enough to convince the client that a reduced amount of N, in the right form, would be desirable. This is the first step I am looking at to satisfy the concerns of myself and those I hope to work for... :)
  4. fl-landscapes

    fl-landscapes LawnSite Silver Member
    Messages: 2,542

    there would be a lot of factors involved so I dont think you will find a definitive answer.

    Fast release verses slow release
    what type of slow release
    liquid or granular
    soil type
    shade or sun
    just to name a few. Maybe someone else has a study sheet they can share I just think the volitization and leaching rates will have a wide range depending on the situation
  5. Smallaxe

    Smallaxe LawnSite Fanatic
    Messages: 10,082

    Agreed, there are a number of factors I'm sure... But if I dump a bag of Scott's on 5000 sq ft., how much N could I lose on sandy soil with no rain... It's not being used by the plant, so does it stay there or does it volitize to some degree? How about clay with lot's of water? There are a number of different scenarios, but certainly not beyond the general comprehension of certain criteria...

    I have seen various 'baselines' in the past , so I was hoping that this type of research has been refined and simplified.... :)
  6. fl-landscapes

    fl-landscapes LawnSite Silver Member
    Messages: 2,542

    Im not trying to be a pain in the azz, but even this will vary depending on what type of slow release N you have. Some are released from moisture activation and some by microbial activity. I think the key is to use a high percentage of slow release fert and only apply the amount that the turf will use at any given time, so timing is key. Light spoon feeding frequently would be ideal but just not practical. The one app "spread it and forget it" has a season long slow release mode of action. I think all applications will have some N volatilize but not necessarily leaching.
  7. Kiril

    Kiril LawnSite Fanatic
    Messages: 18,334

    I don't agree. Nutrient requirements need to be assessed on a site by site basis, and it is possible to have a spectacular lawn with no "additional N".

    This cannot be easily determined. Fertilize on observed need, not perceived need.
  8. phasthound

    phasthound LawnSite Fanatic
    Messages: 5,143

    For those who have not read this link, it also states that synthetic N over time depletes soil organic carbon and soil N due to the increase of certain microbial activity that breaks down organic matter so fast it prevents humus from forming. These microbes also out compete N fixing bacteria in the soil.

    This is a new perspective to me. Tim, Kiril do you have any info on this conclusion?
  9. Smallaxe

    Smallaxe LawnSite Fanatic
    Messages: 10,082

    So I can say there is a 25% leaching of 'water souable N", in sandy soil with SOM < 4.25%, but only a 13% leaching on a heavy loam with SOM > than 3.5%...

    Forget about volatization, because that occurs everytime the soil surface is dried for more than 5 hours. It's just like dumping it out on a sidewalk.

    Since there is nothing written to prove that these figures are erroneous, I could use them because, my detractors would have to prove that these things do not occur, under the circumstances I have laid out...

    That's OK... I can research it myself... :)
  10. JDUtah

    JDUtah LawnSite Silver Member
    from UT
    Messages: 2,636

    Actually, a soils CEC is also a factor to consider while evaluating leach potential. Of course SOM affects this, but you must consider CEC, and amount of moisture, porosity of soil, etc before you can assume any % leach potential.

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