Potassium influences the transport of nutrients and the movement of carbohidrates from the leaf to the tuber. Potassium in potato is critical for high yields. In five trials across three years on K-rich volcanic soils (Ecuador), 107 lb K2O/ac increased average yields by 4.7 t/ac.
It is important that potassium availability is not limiting. Trials in Bulgaria show that potassium nitrate in potatoes is a particularly effective formulation, providing readily soluble and quickly absorbed potassium and nitrate nitrogen in comparison with other potassium forms.
In South African trials, use of potassium nitrate in potatoes in conjunction with calcium nitrate, ensures fast uptake of all three important elements enhancing yield over and above other products.
Potash reduces the level of tuber bruising. Sulfate of potash (SOP) in comparison, can lead to greater bruising than muriate of potash (MOP) when tubers with a high dry matter content are produced, as shown in UK trials.
Sulfate of potash can provide higher dry matter content than muriate of potash, as shown in studies in Denmark. Therefore sulfate of potash is frequently the preferred form for processing potatoes.
Potassium is the nutrient taken up in the largest quantity by potatoes, so it is important that it is not limited during the growing season. Trials show that potassium nitrate is a particularly effective formulation, providing readily soluble and quickly absorbed potassium and nitrate-nitrogen in comparison with other potassium forms. This makes potassium nitrate particularly effective in sidedressing applications during the potato bulking stage. Sulfate of potash is also an acceptable form for delivering potassium. Muriate of potash is less desirable as excess chlorides can reduce quality.
|Potassium at potato growth stages|
|Planting||Early growth and enzymatic activity|
|Post planting||Carbohydrate transport, enzymatic activity, and water status regulation|