BACK TO BASICS – FERTILISERS | TECHNICAL UPDATE
Uniform size is important in granular fertilisers to ensure an even distribution
liquid) are water soluble and offer quickrelease nutrients to the grass plant, when properly applied with the appropriate amount of moisture. Uniform granule size is important for even distribution using rotary spreaders and, for blended products, to ensure there is no segregation of the components in the bag or spreader. However, this immediate effect may not synchronise with the dynamic growth requirements of the grass plant. One solution is to do a repeat application, although too much could cause the grass plant to burn, or nutrients may leach or run off – meaning the plant may not have access to nutrients when it needs them. To address these challenges, slowrelease and controlled-release fertilisers have become popular alternatives because they provide a steady supply of plant nutrients over an extended period of time. For example, nitrogen can be slowreleased for up to four months, even in inclement weather.
Slow release Nitrogen products, decomposed by microbes, temperature and moisture, are commonly referred as slow-release fertilisers. These provide a gradual release of nitrogen and slow down the volatilisation and leaching process, by holding the nitrogen in the soil.
Controlled release Controlled-release fertilisers are coated or encapsulated with semi-permeable polymer or organic materials that control the rate, pattern and duration of nutrient release by slow hydrolysis of watersoluble, low-molecular-weight compounds, designed to meet changing plant nutrient requirements over a period of three, six, nine or 12 months.
Increased efficiency It is important that fertiliser application, whatever its type, is accurate and timely to maximise the nutrient benefits to the grass plant and minimise environmental losses, and using slow- or controlled-release fertilisers allows for less applications, will save on manpower and avoid leaching when the fertiliser is washed out of the soil without ever reaching the plant. When purchasing fertiliser products, ensure you check the package label for nutrient sources and for the levels of salt and chlorides; high levels of these may burn or dry out the plant. NPK should be declared as oxides in percentage format. To calculate the amount of nutrients applied per area, multiply the application rate (kg/ha) by the percentage nutrient content, which may also highlight the amount of fillers within the bag (see panel item, right). ■
The manufacture of slow-release fertilisers COMPO EXPERT’S reputation as a developer and manufacturer of specialist granular and liquid fertilisers is based on its production plants in Germany (for granular and liquid fertilisers) and Spain (water-soluble products). These give the company total control of its manufacturing processes and supply to users of, for example, its slowrelease nitrogen products – isobutylidenediurea (Isodur), crotonylidenediurea (Crotodur) and methyleneurea (MU). The manufacturing plant in Germany is said by Compo Expert to be the only facility in the world that can combine all three forms of slow-release nitrogen. The production process begins with the application of raw materials which are then mixed with key ingredients before milling. After the granulation process, the product is dried, sieved and stored in bulk before bagging. The factory can produce 65,000 tons of pure nutrient fertilisers per year – and it cannot/does not add fillers such as sand, so turf managers are supplied with very cost-effective products. Indeed, with no fillers or inert material added to achieve an 8-0-0 ratio, and no ineffectual chemistry such as magnesium, iron or sulphur at high fractions added to achieve a 7-0-7 ratio, the chemistry on the label is what’s in the bag! Email agronomy@compoexpert.com for more information
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