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Discussion in 'Pesticide & Herbicide Application' started by Nebraska, Feb 24, 2002.

  1. Nebraska

    Nebraska LawnSite Senior Member
    Messages: 525

    Anyone notice differences in using PSCU vs SCU? For example a property treated with an identical formulation of 40% PSCU vs a property with the same formulation of 40% SCU.
  2. Nebraska

    Nebraska LawnSite Senior Member
    Messages: 525

    Did I ask a taboo question?
  3. fireball

    fireball LawnSite Member
    from ne Pa
    Messages: 172

    lack of response may mean there is no difference other than the difference in the cost of your product
  4. tremor

    tremor LawnSite Bronze Member
    Messages: 1,476

    Hello Nebraska,
    I didn't want to answer this one until I had time to do it justice. I'll guess that 75% of the people who sell fertilizer don't know the answer to this one. I will share the answer with you.

    Originally, the Tennesee Valley Authority (TVA) grasped the new SCU technology & conducted the majority of the research on it. They helped determin the process by which all coated nitrogen sources are tested to this day. The procedure is called a "disolution" test. It involves placing a known quantity of the fertilizer into a closed container with water flowing steadily through it, for a specified period of time at a specified temperature. The resulting solution is collected & tested for Nitrogen content & compared with the known quantity that was placed into the chamber. The difference tells us what percentage was recovered & what percentage performed as was engineered. The less recovered the better. This because the SCU shells (molten applied sulfur on urea) has surface imperfections or pores & areas of varying thickness.

    Reacted forms of slow release nitrogen are tested differently & I won't go into that here. Suffice to say that "WIN" has nothing to do with coated materials. That test is not effective on coated materials & would tell us nothing.

    By itself, sulfur has too many pores & imperfections to resist much of the disolution tests water. Around 60%-70% of the well handled straight SCU will pass the test. SCU that is improperly handled by blending & transporting equipment can have it's shell broken and will release more freely. There are fertilizer blending machines that are deemed inappropriate for SCU blending for this very reason.

    The company I work for helped engineer additional compounds to help the sulfur resist water. Wax was an inexpensive & effective additive. We used it for years. The bar was raised to at least 70%.

    The advent of polymer usage isn't very old. About 10 years I'd guess. Polymers & resins can be applied directly to urea, but it becomes a soupy, slimy mess. So SCU is used with the substrate for the polymers or resins being the sulfur layer. The polymers simply fill in & protect the pores. The pores are still needed to insure that water will eventually reach the nitrogen & cause it's release.

    Todays SCU can still range is disolution rate performance. Quite a bit too. We engineer our PolySCU for our own blends at 90% or better. That which doesn't meet spec can be reworked or sold off through brokers. We can produce SCU in the 70-80% range if a customer specifies. The quantities must be substantial. I will not disclose who those customers are. We can also add colorants to the product to alter the finished color. This is rather wasteful & has no impact on the finished product, but marketing people like it. In Germany, our fertilizer is colored brown. Our German customers have to use brown fertilizer. The law requires it. Yellow, green, blue, pink, orange & brown are all produced. Only the thickness of the coating & how well it is sealed will alter the disolution rate. Certainly not the color.

    Our industry doesn't have to tell anyone the disolution rate of the SCU it is using. We would support regulations that required disclosure since we have nothing to hide. We buy & test other SCU's regularly & test it right along side our own. Production planners & plant managers don't know when a quality control test is coming to insure good results. We rarely find competitive materials that match the standards that we impose on ourselves. Most fall into the 60-80% range.

    Poly coating doesn't just slow down the release of SCU. We have a proprietary formula that helps our PSCU resist breakage during blending & transportation. This is important since a lot of our PSCU is sold in bulk to other companies that may not have the luxury of our "SCU friendly" blenders.

    Polymers & resins can be used to engineer some very long release rates. For ornamentals, there are products made that will go all season long. Not very realistic for turf, but in demand by growers none the less.

    I'm sorry this turned into a book, but there is quite a bit more that this forum probably doesn't need to hear.

    I hope this helps.

  5. Nebraska

    Nebraska LawnSite Senior Member
    Messages: 525

    I was waiting for your response and very much appreciate the information. Go on if you wish, I definitely would like to know more. The information is very useful and will be put to good use.


    OBRYANMAINT LawnSite Senior Member
    Messages: 555

    I have also appreciated the nitty gritty aspects of this and of steve's other posts

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