Results 1 to 3 of 3

Thread: Nitrogen/Sulphur conversion

  1. #1
    Junior Member
    Join Date
    Oct 2013
    Location
    Scotland
    Posts
    22

    Nitrogen/Sulphur conversion

    Sorry if this has been asked before but I'm trying to work out sulphur requirements for cereals/rape. Usual choice of fertiliser is 26n 37S. HGCA recommend 25-50 kgs/ha for cereals and 50-75 for rape.

    I still think in units/acre so if I apply 2cwt/acre of 26N 37S that gives 74 units of S (250kgs/ha). That isnt available sulphur to the crop though as it comes in SO3 form in the bag and converts to So4 in the soil. Am I correct in thinking that dividing 74 by 2.5 gives the available sulphur in kgs/hectare?

    Bit confused about differences bewtween S03,So4 and elemental S. Thanks for any advice

  2. #2
    Senior Member
    Join Date
    Feb 2013
    Location
    Gloucestershire
    Posts
    104

    Re: Nitrogen/Sulphur conversion

    Yes, S x 2.5 = SO3. SO3 is wrongly referred to as sulphate (SO4) but is the form of S in most fertilisers. Those HGCA recs refer to SO3 by the way.

  3. #3
    Senior Member
    Join Date
    Feb 2013
    Location
    Somerset
    Posts
    2,820

    Re: Nitrogen/Sulphur conversion

    To turn kg/ha into units/acre just multiply it by 0.8.

    So if you want 75kg a ha you would apply 60 units per acre.

    I too talk in units and acres still as it is still widely used around here. Just dont ask me what a unit weighs.

    It is worth printing a copy of RB209 and keeping the required crop tables as it is a useful source of all the needed conversions. I can never remember the sulphur one, i just know sulphur is declared as SO3 on fertiliser bags.

    All ferts declare the elements in oxide forms so they can be marketed fairly.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •