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Story: Marine minerals

Topdressing on high-country pasture

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Topdressing on high-country pasture

Phosphate nodules dredged from the Chatham Rise and tested on New Zealand farmland have proved suitable for use as a slow-release fertiliser. However, the economics of mining in 400 metres of water for such low-grade deposits make exploitation currently unfeasible. Any proposed deep-sea mining operations on large areas of the sea floor would also need to consider the environmental impacts.

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How to cite this page

Ian Wright, Marine minerals – Phosphates, ironsands and sands, Te Ara – the Encyclopedia of New Zealand, https://teara.govt.nz/en/photograph/5520/topdressing-on-high-country-pasture (accessed 25 June 2026).

Story by Ian Wright, published 2 March 2009.