Potassium fertilization products used for arable crops have not changed much in recent decades. The options generally consist of potassium chloride (K-60), potassium sulphate (K-50), or potassium-magnesium sulphate (K-30). In and of themselves these are good products, yet they provide relatively one-sided nutrition for the plant. For stronger plants and a higher yield, a more complete solution is therefore preferable: Polysulphate.
Polysulphate: a natural mineral
ICL has marketed the natural mineral polyhalite under the brand name Polysulphate since 2014. This low-chlorine mineral consists of the following quality elements: potassium (14% K2O), calcium (17% CaO), magnesium (6% MgO), and sulphur (48% SO3). In addition, Polysulphate naturally contains some boron and other trace elements.
We get Polysulphate from the UK. It is an unprocessed mineral that is mined from the ocean floor. After extraction, the mineral is crushed and screened to a fraction of 2–4 mm. This fraction finds its way to farmers and livestock keepers worldwide.
Prolonged nutrient release
Polysulphate is highly compacted, as it is extracted at a depth of 1250 metres below the ocean floor. As such, the density is very high and therefore the minerals become available to the plant over an extended period of time. Whereas K-60, for example, dissolves quickly in the moisture of the soil, Polysulphate takes longer. This is major benefit of Polysulphate. Fertilizers should be made available exactly when the plant needs them. Clearly, it is of little benefit to a plant to be given a single massive “meal” at the start of cultivation. Some should also be kept in reserve for later.
This characteristic of Polysulphate means the risk of salt damage and leaching is low. Polysulphate has the lowest salt index of all potassium fertilizers and is perfect for use in the cultivation of onions and carrots. It is good for the soil life and for minimizing the pressure on your crop.
Worldwide, more than 700 trials have been conducted with over 70 crops. In the Netherlands, this research has mainly been focused on the cultivation of potatoes, onions, carrots, and cabbages. All the trials have shown that Polysulphate is a very suitable potassium fertilizer. If Polysulphate is used as the potassium basal dressing, the calcium and sulphur requirements of the crop are also covered.
Benefits for organic farming
Polysulphate is an unprocessed mineral and therefore also suitable for organic farming. No excipients are used to formulate or release the product. In both the Netherlands and Belgium the fertilizer has been approved for use in organic farming. Organic growers find the application of four nutrients and trace elements in one go to be a particularly significant benefit.
Polysulphate has quite a low potassium percentage. As a result, the dosage per hectare is relatively high. The advantage of this, however, is that this fertilizer only needs to be applied once per season, and there is no need to think about it again throughout the rest of the season. In addition to potassium, you also get many ‘extra’ minerals as well. It makes a huge difference whether you get 100 units of potassium from K-60 (just 100 kg K2O and a relatively large amount of chloride) or from Polysulphate (100 kg K2O, 121 kg CaO, 43 kg MgO, 343 kg SO3 plus boron and much less chloride). It is the unique quality combination that makes the difference!
Due to the extended availability, we recommend spreading Polysulphate well before cultivation. This way, the initial effect is adequate, and it releases the minerals ‘again’ during cultivation. Then it is usually unnecessary to apply an additional dressing of quick potassium during the season.
Polysulphate is easily spreadable with the current fertilizer spreading technology. The granule is strong, and thanks to its high density the fertilizer can be spread lightly. With Polysulphate as the basal fertilizer, the need to drive between the spray lanes to reach the full spreading width is therefore a thing of the past.
A top quality fertilizer at a competitive price: that is Polysulphate in a nutshell. Polysulphate is available through the normal sales channels. Do you have questions? Feel free to contact us!
4190 CA Geldermalsen
Tel.: +31 (0) 418 655 780
Polysulphate just after spreading. The mineral dissolves on exposure to moisture.
Part of the dissolved calcium precipitates with dissolved sulphate (becomes gypsum) and forms a ‘skeleton’ similar in appearance to the original granule.
Polysulphate gradually releases its nutrients to the soil moisture, and thus the plant, while the skeletal granule remains intact.
The gypsum skeleton gradually breaks down during and after the original Polysulphate mineral dissolves.
The gypsum skeleton softens and dissolves completely.