Sulfate of Potash: More than 100 years of experience

SOP REPORT

Sulfate of Potash: More than 100 years of experience

We talk to Nicolas White, Portfolio & Knowledge Director at Tessenderlo Kerley International, about the company’s new agronomic book on SOP – Sulfate of Potash: More than 100 years of experience. At almost 350 pages, the book is unique in its depth and breadth of coverage.

How valuable is the book in your view and who is it aimed at?

We’re very proud of it. The book brings together all our agronomic knowledge on SOP for the first time in one reference. There’s arguably no other book that covers SOP plant nutrition in such depth.

The information in the book shows how to optimise the use of potassium sulphate fertilizer in crop production. It is the culmination of many years of field trials and, because of this, we believe the book is unique and of real value to growers. It’s sure to become an essential point of reference for every agronomist who provides advice and makes recommendations on potassium fertilization using SOP.

Could you tell us a little more about the author.

Without question, Michel Marchand is one of the world’s leading experts on potassium sulphate fertilization. Michel, who has recently retired, was formerly the senior agronomist at Tessenderlo Kerley International as well as the former chairman of the Sulphate of Potash Information Board (SOPIB) agronomy committee. For many year’s Michel was the foundation of our knowledge base for potash and SOP fertilization.

Many people have benefitted from Michel’s SOP expertise, thanks to his extensive international experience and 40 years working in agriculture. During his distinguished career, Michel demonstrated the benefits of SOP by conducting numerous field trials across the world in collaboration with different research organisations – and then presenting these findings at many international conferences.

The book draws on more than 100 years of expertise. It covers the nutrients needs of a vast array of crops – almost 50 different crop types.

Yes, as you can imagine, it’s taken a huge amount of time and resources over many years to collect this information. Indeed, last year, Tessenderlo Group celebrated 100 years of SOP production in Belgium. In this time we have become recognised as one of the leading suppliers of high quality SOP products.

Our SoluPotasse® water-soluble grade SOP is the market-leading reference product. Tessenderlo Kerley International is also the only company to offer a special grade, K-Leaf® , designed especially for foliar application.

We are also one of the few SOP producers that has a dedicated team of agronomists to advise and support our customers and their growers. Over the years, our expertise has allowed us to build up a network of partners who also advocate the use of SOP – as an important chloride- and nitrate-free potash source. That’s allowed us to enhance and build knowledge on SOP within our team. Our aim, of course, is to continue to share this knowledge!

Has SOP usage by crop type changed and evolved in recent years. If so, what’s been driving that – and where do you see real growth potential ahead?

Globally, the key market for SOP crops remain cash crops – fruits, vegetables and others – where quality as well as yield influence the crop’s marketability and value. In addition, many of these crops are either sensitive or intolerant to chloride, which means the use of potassium chloride as a potash source is not recommended.

SOP has always been priced at a premium compared to MOP, because of the absence of chloride and because of the added value of sulphur in the sulphate form that the product contains. The SOP market has grown steadily over the last couples of decades and has almost doubled over the last 10 years.

SOP growth has more or less tracked the global growth in potash demand. That said, the MOP and SOP markets should be considered as distinct and separate. MOP is used principally in field crops, whereas SOP is used in cash crops. MOP tends to be used in temperate or tropical climates, while SOP is often used in arid or semi-arid climates.

The producers of MOP, with a few exceptions, are also a different group of companies to SOP producers. Hence the market supply-demand characteristics of the two products are very different – as has been demonstrated on several occasions in the last decade.

What we do see for SOP is much more rapid growth in the use of special, high-grade water-soluble products for use in drip irrigation systems. The push for this has been the drive to improve both water and nutrient use efficiency.

The growth in SOP consumption will almost certainly be driven by better product knowledge and information on how to get the best fertilization results. Many of our trials – which feature in the book – have demonstrated the cost effectiveness of SOP use. This is often down to an increase in both quality and yield of the crops. SOP use can also enhance the crop’s shelf life during storage and transport.

One area where we have put in a lot of effort in recent years is demonstrating the effectiveness of foliar SOP for improving yield and quality. Foliar sprays can complement the potash fertilization of soil by providing the crop with a potash boost at times of rapid growth or when the crop has a high need for potassium. The merits of applying foliar potash in the absence of a deficiency is a new idea. So a lot of education is required to make growers aware of the potential benefits.

The importance of high and consistent product quality is one of the book’s themes. Why is it so important to highlight quality when it comes to SOP?

Quite simply because we believe there is a great variation in the market and that growers and fertilizer manufacturers will get the best result from using high quality materials.

Using the best quality SOP products becomes particularly important in the case of water-soluble fertilizers used in expensive equipment such as drip irrigation systems or foliar sprayers. Manufacturers of drip irrigation equipment are often astounded that growers invest heavily in these systems and then damage them by using inferior quality fertilizers.

Our research also shows that modern foliar spraying equipment benefits from a superior grade of SOP that is specifically designed for this use – which is why we developed and market K-Leaf® for this application.

Importantly, the book highlights a quality scoring system we have developed for water-soluble SOP products. This has enabled us to benchmark our leading SoluPotasse® product against other water-soluble products on the market.

The book makes a strong case for the three-fold benefits of SOP, i.e. its chloride-free nature coupled to its ability, as a dual nutrient source, to provide plants with both potassium and sulphur. How valuable are each of these three attributes in your view?

Michel, along with many others, spent a lot of time educating farmers on the importance of balanced fertilization. Despite everyone’s efforts there are still regions where potash is underused compared to other fertilizers. Our team of agronomists continues to work tirelessly to try to change this.

SOP was originally introduced to offer growers a chloride-free potash source for use in crops intolerant or sensitive to chloride. This remains probably the most important benefit and is why growers pay a premium for the product compared to MOP. What we are also seeing is increasing demand in the areas at risk from soil salinity – SOP has an important role to play in these conditions, in our view.

The presence of sulphur in the sulphate form – which is readily taken up by plants – is also a valuable additional benefit now. Sulphur is indeed becoming more important and cases of deficiency are on the increase, particular as growers switch to higher yielding varieties of many crops.

This books isn’t the last word on the agronomic benefits of SOP. I understand you’re publishing authoritative but accessible crop brochures, starting with nutrition guides for potato and grapes.

Ensuring all of Tessenderlo Kerley International’s agronomic knowledge is documented, safeguarded and shared is a key part of my role. In fact, since bringing together our thiosulphate and SOP product portfolios, we have taken the opportunity to review and enhance the information we have available on the use of all products for a wide range of crops.

There is a large amount of information available in our ‘Knowledge Centre’ on our website. We already have a range of application guides for our products, for example. But we’re also starting to build what we hope will be an informative series of crop guides. These are based on the knowledge and experience of our agronomists deployed throughout the world.