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