Potassium Sulphate

Potassium Sulphate (Sulphate of Potash)

Potassium Sulphate, also known as Sulphate of Potash, is a soluble potassium and sulphur fertiliser, 42.00% potassium (50.60% K₂O) and 17.00% sulphur, that is virtually chloride free. It suits fruiting and flowering plants and growers who want potassium without the chloride load of potassium chloride.

At a glance

• Type: mineral fertiliser (soluble salt)
• Supplier certificate on file: BioGro licence 297. See the certificate and its dates.
• Analysis: NPK = 0 - 0 - 50.6 (N, P₂O₅, K₂O); potassium 42.00% elemental; sulphur 17.00%
• Use for: fruiting and flowering plants; potassium top-ups from a soil test
• Rate: 50 to 75 g per square metre before planting; 50 g per established plant at the dripline
• Bulk: 500 kg and 1000 kg quantities available, email store@seaclifforganics.nz for a quote

What it is

Potassium sulphate (sulphate of potash) is a mined and refined mineral salt. It is virtually chloride free and has a lower salt index than potassium chloride (muriate of potash), so it is the potassium source most used in the organic sector. The potassium and sulphur are in sulphate form, readily available to the plant, and it mixes well with other fertilisers.

What it does

• Potassium regulates water movement in the plant and drives bud and fruit density. Deficiency shows as burnt edges on old leaves.
• Sulphur is used for proteins, oils and flavour compounds.
• Both are supplied in soluble form, so they are available as soon as they are watered in.

Analysis

NPK = 0 - 0 - 50.6 (N, P₂O₅, K₂O)

• Potassium (K₂O) 50.60%
• Potassium (K, elemental) 42.00%
• Sulphur (S) 17.00%

How to use

• Seedlings and transplanting: before planting apply 50 to 75 g (about 2 and a half to 3 and a half tablespoons) per square metre of garden. Mix thoroughly into the soil and water in well.
• Established plants: apply 50 g (about 2 and a half tablespoons) per plant around the dripline. Lightly fork into the soil and water in well, taking care to wash any product off the foliage.
• Bulk is available in 500 kg and 1000 kg quantities; email store@seaclifforganics.nz for a quote.
• Potassium competes with magnesium and calcium for uptake, so heavy potassium applications can induce a magnesium deficiency even when the soil has enough. It is a soluble salt, so keep it off foliage and water it in, and apply from a soil test rather than by habit.

Learn more in fifteen seconds

• Potassium: what it does
• Sulphur: what it does
• Mulder's chart: what blocks what

Handling and storage

• Wear a mask to avoid inhaling particles and open in a well ventilated area.
• Wear gloves and eye protection, and wash hands after use.
• Once opened, keep sealed and dry.