ExteNd is a very smart fertiliser as few N fertilisers allow a steady-smooth-ramped release of nitrogen, negligible loss, and no adverse effects to the environment from the coating, it’s natural and biodegradable.
Polymer-coated urea fertilisers use a hydrophobic (water insoluble) coating that temporarily isolates the urea granule from the soil environment. These polymer coatings (extend has 3 coatings ) act as semipermeable membranes or impermeable membranes with tiny pores. Nutrient release through these membranes is controlled by the properties of the coating material, i.e., its permeability characteristics as affected by temperature and moisture. Thus, they are not significantly affected by soil properties such as pH, salinity, soil texture, microbial activity, re-dox potential or cation exchange capacity. Therefore, it is possible to predict and control the nutrient release rate from these products more accurately than for sulphur-coated urea’s. See Accumulation Release Rate Graph later in this outline.
The additional labour and equipment required to produce multi-layer polymer coated fertilisers and the cost of the coating materials can make them more expensive than conventional N fertilisers however the advantages provided largely offset this element.
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