Variable Rate P & K

Discussion in 'Tillage' started by vf949, Nov 3, 2018.

  1. vf949

    vf949 Well-Known Member

    Joined:
    Feb 22, 2013
    Messages:
    459
    A few years back there was some chat on here about variable rate P & K spreading. The general feeling amongst a few was that yes maybe do variable rate lime alright but variable rate P &K wasn't worth the cost and extra work involved.

    Now that we are a few years on, technology has moved on and TAMS has come along maybe a few more people have upgraded Spreaders/GPS systems and started doing variable rate P & K?

    What are peoples thoughts on it now?
     
  2. gone

    gone Well-Known Member

    Joined:
    Jan 16, 2011
    Messages:
    5,675
    Location:
    CW. southeast Ireland
    I variable rate spread P and to a lesser degree K, but no fancy GPS or spreader.
    I go around the areas that are low in P and spread approx 200kg/ha 0/10/20 or TSP in the Autumn, the whole field then gets maintenance P&K in the form of 12/5/25 or similar in the spring and the areas that low in K get an extra approx. 100kg/ha of MOP in early summer.
    I just give a copy of the soil test maps to the man on the spreader with the instructions written on them.
     
    towbar, cormywormy, nashmach and 2 others like this.
  3. Barrowsider

    Barrowsider Well-Known Member

    Joined:
    Oct 17, 2016
    Messages:
    960
    Location:
    East Laois
    I suspect the biggest issue with GPS variable rate P & K application is the need to Purchase and apply both P and K separately (unless you have a front and rear mounted spreader) which complicates a relatively simple job.
     
    vf949 likes this.
  4. cormywormy

    cormywormy Well-Known Member

    Joined:
    Sep 18, 2009
    Messages:
    715
    Local man to me does that, out with straights. Takes a lot more time he says but do see benefits.
     
    Barrowsider, towbar and vf949 like this.
  5. CORK

    CORK Well-Known Member

    Joined:
    Nov 15, 2011
    Messages:
    10,185
    Location:
    East Cork, Ireland
    Is there anyone in the south doing variable rate lime?
     
  6. Bog Man

    Bog Man Well-Known Member

    Joined:
    Oct 16, 2009
    Messages:
    7,664
    Location:
    Carlow
    CORK likes this.
  7. Blackwater boy

    Blackwater boy Moderator

    Joined:
    Sep 24, 2013
    Messages:
    7,087
    Location:
    West waterford
    @Claas Grass is your neighbour at variable rate lime?
     
  8. vf949

    vf949 Well-Known Member

    Joined:
    Feb 22, 2013
    Messages:
    459
    That sounds a good way of doing it without complicated technology! Also the way you do the spreading throughout the season lowers the number of trips through wet tramlines in Feb/March. Have you found that the P & K has evened up a lot not when you test the soils? How often are you getting the soils tested?
     
  9. Claas Grass

    Claas Grass Well-Known Member

    Joined:
    Jun 11, 2011
    Messages:
    1,586
    Funny this topic just started I kind of had a brain fart during the week and was wondering if it would be a service worth looking into. He does his own, that’s about it really and a bit for another tillage farmer.
     
  10. gone

    gone Well-Known Member

    Joined:
    Jan 16, 2011
    Messages:
    5,675
    Location:
    CW. southeast Ireland
    Will only be starting to retest this Autumn and will only be doing problem areas first, but have seen yields evening up.
     
    nashmach, 6600, CORK and 1 other person like this.
  11. WestCorkBoy

    WestCorkBoy Well-Known Member

    Joined:
    Apr 23, 2015
    Messages:
    633
    Did I see a trailer spreader somewhere with a split hopper?? Vague memory of it. P in one section k in the other? Blended before they drop onto the discs? Basically two weigh cell machines with one set of discs. If not then I’ve just invented it. I suppose a front and back spinner would do the same.
     
    towbar likes this.
  12. Claas Grass

    Claas Grass Well-Known Member

    Joined:
    Jun 11, 2011
    Messages:
    1,586
    Dam it I had just invented that idea during the week because the one problem when I was doing it was all the extra traveling when conditions were poor.
     
    towbar likes this.
  13. towbar

    towbar Well-Known Member

    Joined:
    Jan 16, 2011
    Messages:
    2,149
    Location:
    Louth, Ireland
    Don't worry about who invented- its first to file it!!!
     
  14. Bog Man

    Bog Man Well-Known Member

    Joined:
    Oct 16, 2009
    Messages:
    7,664
    Location:
    Carlow
    Forty years ago Oak Park had three Vicon hoppers in a row onto a belt back to a happy dog and could make your own 10-10-20 .
     
    nashmach, towbar, cormywormy and 3 others like this.
  15. Hardysplicer

    Hardysplicer Well-Known Member

    Joined:
    Jan 10, 2015
    Messages:
    1,060
    Variable rate P means using TSP which gets locked up in soil after 8-10 weeks
    While it will raise P index it might not be available
    We have tons of P locked up in soil
    My interest is unlocking this P using various methods
    Index of P doesn’t really bother me as long as you feed crops it’s needs
    Variable rate lime interests me alright
     
  16. Blackwater boy

    Blackwater boy Moderator

    Joined:
    Sep 24, 2013
    Messages:
    7,087
    Location:
    West waterford
    Lime is cheap, does the cost of testing every ha and the technology needed for variable rate justify it, does the over application in places cause enough of issues to justify it also?
     
  17. jf 850

    jf 850 Well-Known Member

    Joined:
    Nov 23, 2013
    Messages:
    4,937
    Location:
    Co Laois
    In my humble opinion , A daft idea ,

    The cost of the technology to implement it , would cost far far more than having your whole farm in index 5 ?

    I could be very wrong though .


    PS , it appears @Blackwater boy was a bit quicker on the key board.
     
  18. vf949

    vf949 Well-Known Member

    Joined:
    Feb 22, 2013
    Messages:
    459
    A lot of the spreaders that are around now should be able to do it with very little upgrade from what I can see. They already have the GPS for guidance, GPS on off for section control and headland on/off. It's the testing and mapping that would probably be the expensive part I would think. The spreading will only be as accurate as the testing that you do I guess.
     
    gone likes this.
  19. Bog Man

    Bog Man Well-Known Member

    Joined:
    Oct 16, 2009
    Messages:
    7,664
    Location:
    Carlow
    We have been spot spreading lime for years . We used test the field with a W pattern but go back with litmus paper kits or one of those probes you get in the garden centers .
    I put up some pictures of the SOYL tests that we got done a few years ago and the cost was easily covered by the saving we made on the lime . We just marked out the field and got the friendly lime spreader to do certain areas .
    I have proved that chopping the straw raised our K levels that were traditionally low .
    I might look into rigging the GPS up to the Bogballe .
     
    gone, nashmach and vf949 like this.
  20. Ugo Schtiglitz

    Ugo Schtiglitz Well-Known Member

    Joined:
    Aug 25, 2016
    Messages:
    747
    Location:
    multi national export platform NE Atlantic Ocean
    I'm inclined to think variable rate pk is a sexy metal solution to a more simple chemistry problem. Build om. Provide more capacity to retain and cycle major nutrients and use less bag. The generated maps are interesting for all kinds of reasons. Mg and ca among them. I've done it on the place here and was trying to spread more compost and chicken shite on the spots with lower pk indices. But I had a thought then.....lightest sandiest spots seemed to correlate with lower indices. My new unscientific theory is that building organic matter with cc and shite and not letting these sandy spots leach will be the best tac.
     
    bagenal, Bog Man and nashmach like this.
  21. Bog Man

    Bog Man Well-Known Member

    Joined:
    Oct 16, 2009
    Messages:
    7,664
    Location:
    Carlow
    How do you calculate the correct amount of fert if I was to use 0-10-20 and a second run of 50 %K.
    Do I multiply the ETSB *.1.6 to give me tonnes of 0-10-20 / field.
    And multiply MOP *2.5 to give me tonnes. /field . And deduct the K in the 0-10-20 to give me the tonnes 50%K
    7E3A6A0A-6E54-4713-B72E-F3223121E73C.png
     
  22. gone

    gone Well-Known Member

    Joined:
    Jan 16, 2011
    Messages:
    5,675
    Location:
    CW. southeast Ireland
    Your P levels must be low enough?
    My reading of it you need 34.02 tons of 16% P and 13.79 tons of 50% K
    Or 54.43 tons of 0/10/20 and that would over supply your K requirement significantly.
    TSP or DAP look more suitable to your needs, if I am reading it, for example is the big field in Kellistown lowish in P (between 3 and 5) and high in K (above 150) ?
     
    Last edited: Dec 6, 2018 at 5:15 PM
  23. Bog Man

    Bog Man Well-Known Member

    Joined:
    Oct 16, 2009
    Messages:
    7,664
    Location:
    Carlow
    There is a big difference between the IAS tests and the SOYL tests as the Soyl test goes down to 15cm and we may have layering due to min tillage .
     
    Ugo Schtiglitz and gone like this.
  24. gone

    gone Well-Known Member

    Joined:
    Jan 16, 2011
    Messages:
    5,675
    Location:
    CW. southeast Ireland
    TSP or
    If it was mine I would use 0/10/20 or 10/10/20 as suits across the whole lot, if you are thinking of selling straw.
     
  25. Bog Man

    Bog Man Well-Known Member

    Joined:
    Oct 16, 2009
    Messages:
    7,664
    Location:
    Carlow
    The lines with the blue are 2017 results of IAS soil test in the same field. The SOYL tests are done to 15 cm where as we would test about 10 cm and have up to recently being chopping and have a huge amount of Biological activity in the top layers .
    There is consistent difference between SOYL and IAS or FBA .
    33171FBD-24AE-4414-91C7-853CC2037124.png
     

Share This Page