Don’t Neglect Potash this Spring

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The owners of the Boulby Mine in the North East of England, the UKs deepest mine, have announced that they will cease to extract potassium chloride, or MOP as it is commonly known, in the next two years.

Boulby supplies over half of the UK’s potash – however it is becoming uneconomical to continue mining potassium chloride. The mine will continue however and will focus on polyhalite production – a valuable fertiliser containing sulphur, potash, magnesium and calcium.

Thankfully there are plentiful global supplies of potash and there are other European sources of MOP – Russia, Germany and Spain all have working potash production facilities, says Tim Kerr, Hutchinsons fertiliser manager.

Tim Kerr

“This means that Polyhalite will undoubtedly become a more familiar product to farmers in the near future, as not only will the existing potash mine convert its production over to this product (marketed as Polysulphate) but also Sirius Minerals are pursuing an ambitious project  to develop a brand new mine producing polyhalite further down the coast from the existing Boulby mine.”

As we approach the first round of spring nitrogen applications, it is worth reminding ourselves of the importance of other nutrients such as potash in contributing to yield, he says.

Nitrogen is a key driver of yield, in part through its role in cell initiation and expansion. Increased cell numbers and size have a positive impact on capturing and converting the energy of the sun into dry matter. More, larger plant cells will consequently require more water to maintain turgor – and potassium is the key element in maintaining the cell tissue’s water content.

“Remarkably, a wheat crop which is not limited by nitrogen will contain between 10 -15t/ha more water than a crop with limited N supply. In order to maintain the benefits of the nitrogen that is increasing the crop’s yield potential, correspondingly more potassium will be needed by the crop.”

“The phosphate and potash recommendations in the tables in the Fertiliser manual (RB209) refer to specific yields (e.g. 8t/ha of winter wheat) and it should be stressed that if your expectation is greater than that, then it is worth paying careful attention to balancing the potash requirements of the crop.”

Mr Kerr points out that early spring is as an ideal time for applying potash, so it is a good idea to check the levels of plant available potassium in your soil by having a sample analysed and ensure that sufficient K has been, or is, applied to meet the crop potential.”

“Yield will be compromised where soil potassium levels cannot meet the demand of the crop. Considering that the peak uptake can reach 10kg/ha per day in cereals through the late spring, it pays to understand the capabilities of your soil and its ability to replenish the K in the water being taken up by the roots.”