CULTIVATION AND TECHNOLOGY Descent to the source of the quality mineral potassium Each explosion loosens about 3 tons of potassium chloride in big chunks. potash, we ascend further to hear where the extracted potash is taken in the world. Solid research first, only then advice After our underground adventure, area manager in the Netherlands for K+S Benelux, Jaap Brink, takes us to the world of potash above ground. He tells the people of the ABN AMRO Bank and chips manufacturer Lamb Weston Meijer (LWM) that traditional potash fertilisation still has a future. You can grow effectively and cheaply, certainly if you compare potash with modern strategies, according to Brink. ‘You hear a lot about liquid fertilisation and tailored fertiliser. But nobody can substantiate the advantage of the use of this, perhaps far too expensive, fertiliser on the basis of long-term independent POTASH FERTILISER To get a good yield of consumption potatoes, two sources of potassium are of importance: the potash from the ground and the potash fertiliser that growers apply before they plant potatoes. The various types of soils need different applications. The potassium situation of the soil is determinant for the amount of potassium the grower needs to apply for potatoes. If the potassium in the soil does not meet the necessary level, extra potassium is needed to bring the level up to the required standard. In potassium-fixing soils, the amount of potassium needed to raise the potassium level is higher than in non-fixing soils. Potassium is therefore an essential mineral for the cultivation of potatoes. Potatoes that have developed without this important element will never grow into their full potential and they will lack the necessary quality characteristics. Nitrogen may be important for a plant’s growth, with potassium added, the absorption will be much more efficient. This will result both in a higher yield per kilo and in bigger tubers and – especially for the cultivation of chip potatoes – more tubers of the right size. Anyway, various researchers have shown that it is specifically the chlorine in the potassium chloride that causes the bigger sizes of many potatoes. Potassium is best known for its quality-improving characteristic. The mineral influences the osmotic pressure in the cells of the plant and regulates the water balance. If potato plants are given the right amount of potassium, they do much better during dry periods, because a plant with ample potassium needs less water per kilogramme of growth. Potassium also influences the activation of the enzyme systems in the plant, which results in a better tuber formation and improved storage of carbohydrates (stronger cell walls). If there is sufficient potassium available for the plant during the growing season, the potato tubers are less susceptible to bruising and also show less grey discolouration after boiling. At the same time, potassium raises the content of antioxidants such as vitamin C and citric acid, which is a characteristic of the mineral that is still very much neglected. Furthermore, the element delays ripening as a result of which growth continues somewhat longer, leading to a higher yield per kg. Potatoes with a proper potassium content are also less susceptible to internal damage and they have better storage qualities, the reason being the lower content of reducing sugars in the tubers. Thanks to these lower contents, the potatoes are still suitable for crisping and chipping after long periods in storage. For chloride-susceptible varieties, K+S recommend low-chloride potassium sulphate as a potassium fertiliser. research results. If this is only about convenience, it’s a bridge too far as far as I’m concerned. Many growers own lovely machinery which they use to fertilise their crops effectively and cheaply.’ This statement fits the K+S group’s mission to inform farmers and market gardeners objectively about achieving profitable crops. This pertains to the domains of cultivation, environment, agriculture and marketing. To be able to handle these processes properly, the grower needs precise and reliable information, according to Brink. ‘This means that, in our view, advice should be preceded by solid research. As K+S Group, we spend a great deal of money on scientific research at recognised, certified institutes such as WUR (Wageningen University), PPO (Research Institute), HLP (research and consultancy) and SPNA (Northern Crop Farming Experimental Farms). This means that you cannot just use the data of a oneyear demo to change somebody’s farm management. Particularly in fertilisation, I see loads of examples of exactly that. I see that growers often take the advice of their advisor blindly, without asking questions about the grounds for the advice. An example is the application of liquid foliar fertilisers. ‘Farmers don’t always know exactly what active substance is in the foliar fertiliser and in what dosage. They spray a few litres of this and a few litres of that on somebody’s advice. I would like to advise people to consider alternatives, also in connection with the price and composition of products, instead of unthinkingly adopting any old advice.’ He also encounters a shift towards specific fertilisation strategies where soil fertilisation is concerned. ‘Why should that be better than applying 20 Potato World 2009 • number 2 Pagina 19
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