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Chemically granulated fertilizer [photo] 

Chemically granulated

The benefits of chemically granulated fertilizer

By Dr. Koos Bornman (General Manager: Strategic Agricultural Services)

Omnia is the only company in South Africa that continues to chemically granulate fertilizer and in a unique way. Omnia uses a modified "Odda" process or nitrophosphate process during which rock phosphate is attacked with nitric acid instead of sulphuric acid. This process is extremely energy efficient and much more environmentally friendly. It also allows for more secondary nutrients to remain present and available in the fertilizer granule: These nutrients include calcium, magnesium and also specifically sulphur. The most important aspect of chemically granulated fertilizer, apart from the homogenous size distribution of the granules and their hardness and stability, is the fact that every granule contains exactly the same concentration of every nutritional element.

Potential margin loss due to sulphur deficiency at a potential yield of maize (7 to 11 t/ha). A price ratio of 3:3 Sulphur:Maize grain was used. Data used was sourced from a scientifically published article by Omnia in 2004 (40 trials over 4 years), and data published by IMC in 2003 (50 trials over 3 years).

Trials conducted by the University of the Free State have proven that the unique from of phosphate known as nitrophosphate and the presence of secondary nutrients, have a higher relative agronomic efficiency benefit. It was found that nitrophosphate offers an efficiency benefif of between 16% and 22% per unit phosphorus compared to MAP. This was similar to data reported by researchers in Europe (University of Goettingen), which also stated an efficiency benefit of 20%.

The presence of a relative high concentration of immediately available, non-acidifying sulphur in the form of sulphate in Omnia's fertilizer, has great financial benefit. Elemental sulphur is often used in bulk blends, which is extremely ineffective and highly acidifying. Graph 1 shows the risk of margin loss if too little or ineffective sulphur is used in the production of maize. As the graph shows, Omnia's data is actually confirmed by international data (IMC Fertilizer Group). Omnia's fertilizer offers the peace of mind that the correct amount of sulphur will be applied in an immediately available form.

Except for the abovementioned benefits, chemically granulated fertilizer offers the benefit of homogenous distribution of nutrients when spread or placed. The prolem with bulk blended fertilizer is that the raw materials are not homogenous in size, form or density. These blends often contain high concentrations raw materials such as urea, which means that small volumes per unit product are used, exacerbating poor distribution. The primary problem is the segregation of raw materials during blending, bagging, transport and application (refer to Photo 1). Uneven distribution of fertilizer sources during the spread and placement of fertilizer leads to a lack of nutrition, as well as fertilizer burn. International research (Levington Agriculture in the UK) showed that a coefficient of variation of as little as 30% in distribution can lead to yield losses of between 3% and 22% on wheat.

Kansas State University in the USA recorded yield losses of 25% on soybeans following uneven placement of calcium chloride. Omnia's own maize trials showed that a 20% yield loss is possible on sandy soils, while a 10% yield loss can be expected on loamy soils.

This article was published in the Nutriology® Newsletter (Summer 2012).