NZ currently uses about a million tones of phosphate fertiliser each year. Its use underpins our entire agricultural economy so in the context of global shortages of oil and other resources, it should play a big part of our discussions. According to the U.S. Geological Survey “There are no substitutes for phosphorus in agriculture” (organic and permaculture aside). We currently import 80% of our phosphate fertiliser from Morocco.

While Morocco has their name on the manifest of the bulk carriers that regularly stop off at Tauranga, Napier and Port Chalmers, the phosphate in fact comes from West Sahara. This region is under military occupation by Morocco and while the NZ government acknowledges the occupation is illegal, the importation of phosphate from Morocco is allowed.

Ethics aside, we don’t currently have too many options. Morocco controls two thirds of the world’s phosphate resources and are happy to do business with the West, but they themselves are facing “peak phosphate” in the near future. Just like oil, we are a small player at the end of a long, fragile supply chain. We are dreaming if we think we can keep importing it indefinitely in the face of a global shortage.

The price of rock phosphate has gone up tenfold in the last year - from $US50 a tonne to $US490 and this is making a local source of phosphate near Milton, in the South Island a viable option again. The Milton deposit was last commercially mined during World War 2 when Japan took control of Nauru, our source of phospahte at the time. Fertiliser co-operative Ravensdown has signed up mineral and land agreements over 72ha but they are looking at as much as 500ha.

This deposit could provide us with 10 years of self-sufficiency in phosphate if it proves viable to extract it. Once world phosphate supplies start to decline, they are gone forever so surely the smart thing would be to keep ours in the ground as long as possible, giving us a 10 year window to mitigate against peak phosphate by adopting new practices. Industrial agriculture and horticulture will not exist without an abundant cheap supply of phosphates and we know a time is coming when they will be gone.

Something as vital as a 10 year reserve of phosphate should be nationalised as part of a complete food security strategy - this is simply too important to leave it to the markets to decide what to do.