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Fertilising is conducted every year as the final part of the mine rehabilitation process. Each summer, all pits in which mining has been completed are rehabilitated.  This rehabilitation commences during November and is completed in April each year.  During the following winter, once temperatures have cooled and the winter rain has set in, the seeds in the rehabilitated areas germinate. All newly rehabilitated pits are fertilised during August to encourage strong growth of these new seedlings.
A single application of fertiliser is applied. The fertiliser contains nitrogen, phosphorous, and potassium, and also the micronutrients copper, molybdenum and zinc. The nitrogen, phosphorus and potassium application rates are 40, 40 and 25kg/ha elemental respectively.
The fertilising process has been continually reviewed and improved over a number of years.  Alcoa’s research into fertilising techniques has found that the most efficient method of fertiliser application is by aerial top dressing using a helicopter.  Aerial top dressing removes the need to have machines travel over the rip lines, a practice that is not safe for operators and causes re-compaction of the topsoil.
Fertilising newly rehabilitated pits by helicopter requires a great deal of coordination between the ground crew and the helicopter fertilising crew.  Strict safety procedures and training for all personnel involved is vital to ensure that the operation runs efficiently and safely.

Helicopter hovering whilst hopper attached

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A Loader is used to fill the helicopter hopper and the helicopter engineer opens the shoot while the helicopter hovers.

helicopter flying with hopper attached

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The helicopter carrying a hopper full of fertiliser.