http://www.soilassociation.org/farmersgrowers/technicalinformation/fertilisers/potassiumfertilisers
Potassium fertilisers : Soil Association

Potassium fertilisers

Product Name Classification Company Name Telephone Number (Sales) Product Description Product Use Standards Category

Hortisul

Potassium fertiliser K + S UK & Eire Ltd 0800 0322480 Natural soluble form of sulphate of potash for foliar or fertigation use Foliar or fertigation use for all crops requiring potassium and/or sulphur Prior approval required
K Max Liquid potassium fertiliser Ilex Envirosciences Ltd 01673 885175 Liquid Molasses based fertiliser A very high K based fertiliser for fruits and flowering crops Permitted with justification required at inspection

Magnesia-Kainit

Potassium fertiliser K + S UK & Eire Ltd 0800 0322480 Natural screened crude potash salt supplying potassium, magnesium, sodium and sulphur For use in grassland, carrots, beet, asparagus.Super partner for slurry Prior approval required

Patentkali 'Granular'

Potassium fertiliser K + S UK & Eire Ltd 0800 0322480 Natural granular sulphate of potash with kieserite fertiliser Granular application to all crops and grass requiring potassium, magnesium and / or sulphur Prior approval required

Sulphate of Potash (SOP)

Potassium fertiliser K + S UK & Eire Ltd 0800 0322480 Natural granular sulphate of potash fertiliser Granular application to all crops and grass requiring potassium and sulphur Prior approval required

Nugro 4-2-6

Potassium fertiliser Nutrel Products Ltd 01522 704404 A cost-effective high K product, combats potassium deficiency crop limitations Free-flowing, good water solubility and with minimal sedimentation Permitted with justification required at inspection

Organomex 

4-2-6

Potassium fertiliser Omex Agriculture Ltd 01553 816016  A high potash foliar fertiliser Used in fertigation or as foliar spray when root uptake limited Permitted with justification required at inspection 

Solufeed NPK  6-5-10 + 4% MgO

Potassium fertiliser Solufeed  01243 554090  Balanced feed with added MgO  Used extensively by compost manufacturers  Prior approval required 

Laws High K 

Potassium fertiliser Law Fertilisers Ltd 

01354 740740

Please see company website for more information about product  Please see company website for more information about product Permitted with justification required at inspection

Cumulus NK 5-1-10

Potassium fertiliser Fertile Fibre 01432 853111  N(5)  P2O5(1)  K2O(10) Protected and field scale production  Permitted with justification required at inspection 

An explanation of the "standard categories" for use of organic products are as follows:

Permitted:  
You may use this product.

Permitted with justification required at inspection:
You may use this product but you must be able to justify its use at your inspection with evidence such as test results, records, forms a plan etc. For example you must record why you needed to use that particular product.

Prior approval required:  
Before you use the product you must have been given approval by your certification body. This approval may cover more than one use. For example you may submit an annual plan to your certification officer that will then need to be approved before you can use the product.