Apr 6, 2009
K+S UK & Eire Ltd: Crop Nutrition Update
In 2005, Potash Ltd (now K+S UK & Eire Ltd) embarked on a series of independently managed UK field trials in order to answer some of the questions that had arisen concerning the nutrients Potash and Magnesium and to fine tune crop recommendations for these major nutrients.
Now, 4 years later, Independent trials contractors Armstrong-Fisher have successfully completed over 24 fully replicated and statistically analysed field trials in representa tive areas of the UK and we are pleased to summarise their findings below.
What yield penalty might you expect if you omit Potash?
The fact is that K for a crop comes largely from the soil reserves and K is only applied to replensish that which is removed from the soil to maintain a potash index of 2-, the economic optimum for K levels. On a site in Norfolk with an initial K index of 1, a long-term trial has been set-up to look at the penalty for omitting potash. The trial will last at least 5 years and we are expecting to see drastic results in crops after 2-3 years, where N efficiency is compromised.
A crop of winter malting barley was grown in 07/08 and in the first year of the trial, the control plot with no K already suffered a 0.57 t/ha yield penalty. Watch this space for the results from year 2, another crop of winter barley.
MOP or SOP for potatoes?
MOP (Muriate of Potash) is potassium chloride, whereas SOP (Sulphate of Potash) is Potassium Sulphate. Crops can be classified according to their tolerance for chloride, which is an essential crop nutrient but which can prove harmful to some sensitive crop types. Most of the combinable crops and grass can tolerate chloride containing fertilisers but most vegetables, fruits and potatoes prefer K in the sulphate form. Use of SOP is also known to improve the quality of fruit and vegetables. Production of secondary plant substances such as vitamins, organic acids, aromatics and plant sugars proceeds more efficiently in the absence of chloride containing fertilisers.
Yield of potatoes also improved
3 potash sources were tested in potatoes in six trials over 4 years. Yield with SOP was greater than where MOP was used and better still was Patentkali, a compound fertiliser containing SOP and water soluble magnesium from Kieserite.
Is Korn-Kali an effective alternative to MOP?
Korn-Kali was new to the UK in 2006 and is a potash fertiliser balanced with magnesium and sulphur. Korn-Kali contains K and Mg in the correct ratio for combinable crops, sugar beet, grass and maize and all nutrients are in water soluble form. So how does it compare against MOP in field trials? A total of 6 trials were conducted in cereals and 5 in OSR, the conclusion was clear that cereals and OSR respond to a maintenance application of water-soluble magnesium and are also possibly responding to a little extra sulphur. It was apparent that the additional yield was from a larger number of tillers and an increased grain size.
Which form of magnesium fertiliser?
Magnesium fertilisers come in different forms with very different chemical properties, so how do they perform in the field?
In our Potash mines, the unique mineral Kieserite (naturally occurring magnesium sulphate) can be found. It is used as a high grade Mg + S fertiliser since both nutrients are in the water-soluble and therefore cropavailable form.
A total of 10 field trials were conducted in two highly magnesium responsive crops, potatoes and sugar beet and the results are clear.
Is there a yield and/or quality response from using EPSO products (foliar bittersalz)?
Many crops receive an application of bittersalz with the fungicide program to correct or prevent magnesium and/or sulphur deficiency. The burning question from you is "Is there a yield response or just cosmetic ‘greening’ of the crop"?
A total of over 20 trial results have been generated in OSR, cereals, potatoes and sugar beet and the mean results are presented below proving that EPSO products are highly cost-effective at preventing and relieving stress to crops through nutrient deficiency. K+S UK & Eire wish to thank Dr. Mike Armstrong and Simon Fisher for their great efforts and diligent trials work over the past years.
For more information or to discuss any of these trials in greater depth, please contact our dedicated technical helpline on
FREEPHONE 0800 0322480