Nitrogen is an essential nutrient to fuel canopy growth, however in temperate climates, an excess supply of nitrogen at later stages of growth will keep the crop growing, delaying maturity and may reduce starch and dry matter content, reducing processing potato crop quality.
This trial in Norway demonstrate that too much late nitrogen can reduce tuber dry matter.
Too much late growth in cool climate crops can also result in a crop with many 'oversize' potatoes and cause internal cracking.
The form of potassium has an effect on dry matter. Sulphate of potash - SOP (potassium sulphate) can achieve higher dry matters than muriate of potash - MOP (potassium chloride) and therefore is frequently the preferred form for processing potatoes. This is due to the chloride in the muriate of potash having a negative effect on tuber dry matter content.
This study from Denmark demonstrates the higher dry matter content achieved with SOP (potassium sulphate) rather than MOP (potassium chloride).
Low levels of magnesium will reduce the starch content of tubers and trials have confirmed the positive benefits of magnesium on tuber dry matter and specific gravity.
Low levels of manganese also reduces the starch content of tubers and so reduces tuber dry matter.
Our collection of tools help you to make better nutrient decisions in making the right fertiliser choice and applying the right amount of nutrients at the right time and in the right place so that the crop yield and quality can be maximised whilst still keeping costs in check, avoiding over-fertilisation and protecting the environment.