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Potassium (K), magnesium (Mg), sulphur (S) and phosphorus (P) serve as the foundation for quality, yield and storage qualities of potatoes; foliar applied trace elements such as boron and manganese provide the “icing on the cake”. K+S KALI GmbH, with its competence and experience concerning potassium and magnesium, develops and tests fertilisers targetted for an optimum and balanced nutrient supply for the potato crop. K+S KALI GmbH’s agronomists will be pleased to share their specialised knowledge at the PotatoEurope 2010 show in Bockerode, Germany and look forward to some well-informed expert discussions with you.

The K+S KALI agricultural experts keep emphasising that potato fertilisation needs to be adjusted to the expected yield and to the intended end-use of the crop. Their recommendations are based upon the results of extensive field trials, and may be summarised as: “Don’t scrimp on potassium!” Next to nitrogen, potassium greatly influences yield formation and quality characteristics.

Potassium secures high yields and premium quality

Quantitatively, the potato plants’ uptake of potassium is most pronounced. This explains potassium’s significant role for yield and quality. For each tonne of tubers harvested, the crop will withdraw from the soil approximately 6 kg K₂O so a 60t/ha crop will remove around 360 kg K₂O/ha which must be replaced to maintain soil fertility.

Potassium positively influences:

• vigour and health of the haulm,
• efficiency of nitrogen utilisation,
• correct water balance of plants,
• tuber yield and vitamin C content,
• storage characteristics.

Quality requirements for potatoes are determined by their specific intended use (table potatoes, processing potatoes, starch potatoes or seed potatoes). Processing potatoes (used for chips and crisps), for instance, require medium dry matter levels, whilst those destined for starch production require high dry matter levels.

For table potatoes, cooking properties are more important than starch content. These table potatoes should not disintegrate and should not show discolorations. In order to meet these specific quality standards, it is important to choose appropriate varieties and to adapt fertilisation accordingly. The nutrient potassium influences a range of quality characteristics, affecting the proportion of marketable products.

• Potassium reduces the tubers susceptibility to internal ‘black spot’, after-cooking blackening and crude pulp discolouration.
• Potassium increases citric acid and vitamin C contents of the potato, and influences its starch content.
• Potassium reduces the content of reducing sugars (important for industrial processing).
• Well-adjusted potassium fertilisation improves both harvesting compatibility and storability. The resulting greater tuber maturity reduces post-harvest bruising.

To overview The world of potato at PotatoEurope 2010