The environmental benefits of controlled release fertilisers (CRFs)
Commercial growers facing ever-increasing input costs may be pleased to learn that, according to ICL Specialty Fertilisers’ technical manager Andrew Wilson, growers "use a lot less fertiliser" when they use CRFs. "If you’re just using a water-soluble product it’s a bit of guess work and so a lot of it is not taken up by the plant and is wasted." He explains that, whilst CRFs release nutrients as the plant requires them, growers using water-soluble fertilisers have to continuously apply those fertilisers throughout the year. "That would be very wasteful, very inefficient and poor for the environment because you get a lot of wastage. This waste goes into the drainage water and then eventually into the ground. But for container nursery stock, for example, you could use a 12–14 month CRF product, apply it at potting and it would supply nearly all of the nutrients that the crop needs for the whole of its crop cycle."
Wilson warns that there’s a lot of environmental pressure to keep water clean and so "it’s really important to fertilise plants as efficiently as possible." The EU’s Water Framework Directive, for example, stipulates that farmers and growers should do their utmost to protect the water quality across Europe by preventing nitrates from agricultural sources polluting ground and surface waters.
When should CRFs be applied?
CRFs can be mixed into the growing media or applied when nursery staff members are potting up. A technique named dibbling, introduced to the horticulture industry by the Sierra Chemical Company in the 1980s, helps growers with this process as it sees the Osmocote pellets placed into a hole in the growing medium and the plant placed over the Osmocote. Wilson says: "The fertiliser will release right through the growth cycle and until you sell the plant. And you will probably still have some release left when the plant reaches the garden centre." Occasionally, water-soluble fertilisers and topdress fertilisers are used in addition to CRFs, such as when a grower decides that a plant needs an extra boost towards the end of its growth cycle.
Osmocote – "meeting the plants’ demands"
Producing high quality plants that fly off the retail shelves or bedazzle a landscaping scheme is the aim of all commercial growers. For this reason, simply guessing what kind of nutrients a crop needs – and when it requires them – is perhaps too much of a risk.
ICL’s technical manager Andrew Wilson therefore asserts that the primary reason for using Osmocote is that "we can advise on the exact rate of fertiliser that you need to use for a certain crop, and ensure that the CRF matches the plants’ demands throughout its growth cycle.
"That’s what we do, we advise growers specifically on how to use the technology." Wilson also asserts that, whilst other CRF products on the market may be "sold for a price" ICL "develops the latest technology and tests the products and gives the best back-up in the field."
He adds: "We are able to go and visit the grower, talk about the crop, talk about the release pattern, and show them how it will actually release on the nursery." Usefully, ICL has developed a precision nutrition software tool named Angelaweb which – by taking note of the grower’s crop type, variety, growing media, growth phase, and water application methods – enables ICL’s advisers to calculate a tailored regime for a grower’s crop. "We can show them what the release will be for their crop and how it matches the plants’ demands," says Wilson.
He also divulges that other CRF products on the market are often second generation products. "They will just quote the longevity, such as 5–6 months, 8–9 months or 12–14 months – but they won’t say how they are released within that period. You won’t see any [graphs showing] curves or any information about the release pattern. So, when we talk about Osmocote Exact – it’s a third-generation product and as we’ve tested it before we released it we know exactly what the release pattern is.
"We know that they are slower at the start and then release more [nutrients] later in the growth phase. And when we get onto the fourth generation product, Osmocote Exact Hi.End, we double-coat some of the particles so that we can further delay the release at the start but have more nutrients released at the end. That’s really important because it’s all about meeting the plant’s demands. A young plant, when it is very small, doesn’t need a lot of fertiliser. But as it grows and starts to flower the demand for nutrients is much higher. So that’s when Osmocote High.End comes in and that’s where our market is moving. The more technical growers who are trying to get the best results will use Osmocote Exact High.End because it’s very efficient and you get the best quality crop."