Potassium has an important role in the control of the plant water status and ionic concentrations inside plant tissues, including stomata. As a result of the improved cell strength that potassium provides in potatoes, stress such as frost can be better tolerated, as study in India shows.
Potassium also influences the transport of nutrients and the movement of sucrose 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.
It is important that potassium availability is not limiting. 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 dry matter|
|Post planting||Growth and dry matter|