Incorporation of RPR into Overseer a big step forward

22 November 2016

Incorporation of RPR into Overseer a big step forward.

Overseer is a software tool widely used by New Zealand farmers to tailor fertiliser use to optimise farm production while minimising environmental impacts.

Developed originally by AgResearch, it’s now jointly owned with the Ministry of Primary Industries and the Fertiliser Association.

Recently the software application was upgraded and now recognises the benefits of reactive rock phosphate (RPR) as a fertiliser. In particular, the use of RPR results in less phosphate run-off into streams and lakes than would be the case with manufactured phosphate fertilisers.

Overseer calculates the use of RPR immediately reduces phosphate run-off by 18%. According to independent studies, changed farming practices resulting from using RPR over an extended period could result in up to 80% less phosphate run-off.

This advance represents formal recognition by government and the fertiliser industry that RPR offers a more environmentally friendly source of phosphorus to New Zealand farmers. Over time this should result in increased use of RPR as it is substituted for superphosphate and other phosphate fertilisers.

This is very relevant to Chatham Rock Phosphate because our rock phosphate is a particularly effective form of reactive rock phosphate, demonstrated by extensive field trials undertaken in the mid-1980s and reinforced by recent tests.

As well as representing a secure local source, Chatham Rise-sourced RPR contains ultra-low levels of cadmium levels and creates far fewer carbon emissions, so has a much lower carbon footprint than current northern hemisphere supplies.

As the Chatham Rise deposit will likely not be mined until 2020, we have identified several overseas sources of RPR and can import this rock on request. We are already working with a private New Zealand-based fertiliser company to satisfy the existing demand for reasonably priced material.

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