Potassium deficiency in potato results in poor quality tubers and reduced yields. The problem of potassium deficiency is common in soil in many parts of Malawi. Symptoms of potassium deficiency in potatoes are poor root and leaf growth, which subsequently leads to poor water and nutrient uptake of other crop nutrients, thereby rendering the crop susceptible to diseases and adverse weather conditions. Potassium deficient plants appear stunted and thick. Yellowing symptoms between the veins are expressed first on the older leaves. As the deficiency becomes more severe the edges of the leaves become brown and necrotic and brown spots can appear between the veins on the leaves.
Potassium helps the plant to grow and produce high quality tubers. Potassium gets depleted in the soil through uptake by plants and leaching. Poor root and leaf growth leads to poor water and nutrient uptake, resulting in increased crop susceptible to diseases and adverse weather conditions.
Potassium deficiency can be managed by applying the following:
- Apply manure e.g. well-decomposed compost and khola manure. Apply between 12.5 and 25 tonnes of compost or khola manure per hectare using one to two 20 L tins of manure by broadcasting every 8 metres (8 steps) along the grooves.
- Inorganic fertilizers such as D compound applied at the rate of 200 kg/Ha using cup No.5 equivalent to a drink bottle top with lining inside in the grooves. Between three to four weeks after planting, top dress with CAN at the rate of 150 kg/Ha by applying the fertilizer along the plant rows on the ridge and covering it with the soil.