To assess the value of muriate and sulphate sources of potassium on growth and yield of wheat when applied by banding and topdressing at seeding time or topdressing after emergence.

• Mace wheat responded positively to K.
• Source of K (SOP or MOP product) and timing had minimal impact on growth or yield response.
• Drilled MOP at 100 kg/ha produced the greatest yield and returns but evidence that drilled K is better overall than topdressed applications was not conclusive.
• SummitQ soil test modelling gave an accurate prediction of optimal K fertilizer rate.
• Grain quality was characterized by low hectolitre weights, but increasing K application improved both hectolitre and screenings quality aspects.