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  • At sowing 15 May 2018
  • At harvest 4 October 2018




Potato (Solanum tuberosum cv. Russet Burbank)

Soil Type

Acidic, loamy sand soil


Yield, and quality

In this trial in Wisconsin, USA, Polysulphate fertilizer increased the marketable yield of potato by 15%.


Wisconsin, USA


To evaluate Polysulphate as a substitute potassium, calcium, and sulphur from muriate of potash and gypsum in conventional practice, for potato ‘Russet Burbank’ grown in central Wisconsin.


Grower practice consists of 37 kg N/ha applied at planting as DAP. At emergence and active growth, 85 and 190 kg N/ha was applied, respectively as ammonium sulphate and ammonium nitrate. Phosphorus, derived from DAP, was applied at 185 kg P2O5/ha at planting. Potassium was applied pre-plant at 310 kg K2O/ha as MOP, and at 135 kg K2O/ha as SOP at planting. In addition, at pre-plant gypsum was applied at 560 kg/ha.

The Polysulphate treatment was a duplicate of the grower practice without the pre-plant MOP and gypsum. Instead, Polysulphate was applied at 1,680 kg/ha at pre-plant.


  • Polysulphate fertilization increased the marketable ideal* yield by 1.79 ton/ha over conventional grower practice
  • Marketable yield increased by 15% with the addition of Polysulphate

* The ideal yield is 6-16 oz or grades 2-4. Marketable yield excludes hollow tubers.