What would your expert opinion be on this report?

Discussion in 'Pesticide & Herbicide Application' started by Hamons, Feb 26, 2003.

  1. Hamons

    Hamons LawnSite Senior Member
    Messages: 706

    Thje way that I understand it is that the Cation Exchange Capacity is a measure of the soils ability to hold and supply nutrients. The organic matter and clay fractions of the soil have chemical structures that produce sites with partial negative electrical charges. These are cation exchange sites. Positively charge ions, such as potassium, magnesium, calcium, hydrogen, ammonium, and sodium are called cation. The cations are attracted to the sites negative charges and held there. The cation exchange capacity is the amount of cations a soil can hold and is expressed as milliequivalents per 100 grams of soil.

    Basically it shows how much nutrients each soil particle can hold onto and absorb. A higher CEC is better. With a low CEC then you will have to fertilize less and more often.

    This is at least what I have found out through my research.
  2. Ric

    Ric LawnSite Fanatic
    Messages: 11,969

    Oops your post is better than mine so I will just edit mine out
  3. lawnstudent

    lawnstudent LawnSite Senior Member
    Messages: 472

    A couple of additional points on cation exchange is that when there is sufficient soil moisture, these cations can be actively moved into the turf root. Nutrient uptake by a root is an active process. That is it requires energy expended by the root to move a cation from a cation exchange site into the root. This energy is only available to the root if oxygen is present in the soil. That is because the expenditure of energy requires respiration, a chemical process that uses oxygen as one of the reactants. Without oxygen, the root can not actively absorb the cation because it does not have the energy to do so.

    Also, the root replaces the nutrient cation at the cation exchange site with a hydrogen cation. This is one reason that soils become acidic over time. Your turf, as it absorbs nutrients, is placing hydrogen ions at the cation exchanges sites and pH is the inverse measurement of the number of these hydrogen ions in your soil.

  4. Should never have problem applying lime if you Never exceed 40 to 50 lbs / 1000 per application. If soil test exceeds 50 lbs / 1000 make more than 1 application. DON'T use dolomitic lime if base saturation of mag is adequate (10-15%). Soil test recommendations will specify dolomitic or calcitic lime. Occasionally hydrate lime can be used. Be careful, because its hot and will burn turf. I think, but you would need to research, that 10 to 20 lbs /1000 per application is MAXIMUM. Also make lime applications @ 3 months apart.
  5. lawnstudent

    lawnstudent LawnSite Senior Member
    Messages: 472

    Hydrated lime is not normally recommended for general turf apps. Hydrated lime and ammonium-based nitrogen ferts can interact and form ammonium gas which will kill your turf. Also, applying hydrated lime (even at low rates) to wet turf will burn. Applying hydrated lime at more than 25 lb. per 1,000 sq. ft. will injure the turf.

  6. thanks lawnstudent
    Been awhile on hydradeD lime, but I wasn't to far off. Believe it was an old recommendation to help control moss or algAe or maybe both.
  7. xpnd

    xpnd LawnSite Senior Member
    Messages: 378

    An opinion however I would be the last to qualify myself as an expert.

    pH: Compared to 7.0 your soil is very acidic at 5.5. pH changes exponentially from number to number not linear as the numbers suggest. Why is the recommended pH of soil supposed to be 7? Because 7 is neutral and neutral is good so logic dictates that ideally soil pH should also be near 7. But that logic is flawed. What usually is not considered is adaptability of plants. My Bermuda grass here in TX would probably take a beating in your soil because "my" turf is adapted to not only alkaline conditions, but very alkaline conditions. I don't know anything about Kentucky bluegrass but I bet the reason it is grown in your area is because it is highly adapted to acidic conditions. Your soils would be great for growing azaleas. The transplanted Yanks down here who refuse to let go of such plants have a chlorotic mess in two months and they can't figure out why they don't bloom. DUH!! The soils ability to counteract any applications to change pH is unlimited. No matter how much lime you put down the result if any will be very temporary and restricted to the the first couple of inches of soil. TDA did a study of our caliche soils in N Texas to determine how much sulpher would be required to change pH. To simply negate the action of the Carbonate molecule, 1 acre of turf would require >43K lbs of sulpher in one year. This amount is required so the next lb of sulpher will change the pH. The point to this diatribe is if the existing plants and turf are adapted to acidic conditions and only new plants are selected that like acidic conditions then trying to change pH is no longer a burning issue.

    Amount of P. I wish mine were so low. Because most of our subs are former cotton fields, our P readings are typically within the 2000-3000ppm range from the prior use of super phosphate fertilizers.. P generally is a very stable nutrient in the soil. With modern mulching machines, very little P is ever required once the ideal level is present in the soil.

    My opinion for your needs is very simple. Simply use a fert ratio with a 3-0-1 with a 60% N slow release with a full range of trace minerals and elements unless of course you are trying to grow plants that dislike acidic soils which will then require the yearly applications of lime.

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