Ravensdown does not fear seizure of phosphate fertiliser bound for Napier, from the disputed territory of Western Sahara, although a competitor's US$5million shipment has been held up by a South African court.
The Ballance Nutrients phosphate was held up in Port Elizabeth following a complaint from the Western Sahara Polisario movement to a maritime court.
Western Sahara is a former Spanish colony that resisted Moroccan annexation in 1975 after Spain withdrew. In 1991 the United Nations brokered a ceasefire and promised a referendum on independence which has not taken place.
South Africa does not recognise Morocco's annexation of Western Sahara and is considered sympathetic to the Polisario Front resistance movement. Ravensdown shipments do not visit South African ports.
Western Sahara Resource Watch has called for a halt in the phosphate trade until Western Sahara people choose between independence and integration with Morocco.
Ravensdown chairman John Henderson said the board had long monitored the issue, seeking independent reports and advice.
"It is an incredibly complex situation and very, very politicised," he said.
While mining the resource might be legal under international law the morality of mining a natural resource in disputed territory was just as important, he said.
"Even when you examine it morally or ethically you also end up with two camps - it is very complex."
He said he is visiting the region in three weeks "which is my opportunity to look at one side of the fence".
The other side of the fence was in Algeria where Polisario is based.
"Nobody has been brave enough to say they'll take me to Algeria so I can have a look there as well."
He said Morocco was very conscious of criticism and gave Ravensdown reports on "duties incumbent upon them under the UN mandates" that their activity benefit local people.
"We have seen proof of that in terms of the hospitals they have built, education systems, general welfare and employment opportunities created. Admittedly it is only one side of the argument but that's the evidence we have seen thus far."
He said there were alternative supplies of rock phosphate, many containing high levels of toxic cadmium, and using Moroccan rock in the mix gave a superior product.
Ravensdown, a farmer-owned co-operative, had omitted Moroccan rock in the past "at the expense of the New Zealand farmer".
Ravensdown chief executive Greg Campbell has visited its Moroccan supplier in Western Sahara twice.
He said all Ravensdown suppliers received regular quality, environmental, social and pricing audits.
A Canadian study concluded the indigenous people would suffer more should the Western Saharan resource be blacklisted, he said.
The region had three quarters of the world's known phosphate reserves "and if it wasn't available, then globally we could have social unrest because we wouldn't be able to produces the food people need".
Mr Henderson said the New Zealand Government, the United Nations and independent legal advice all said accepting the phosphate was legal and Morocco reportedly compliant with United Nations mandates.
"We really see this as an issue for the United Nations to sort out."