Yesterday, that anniversary was acknowledged by staff and management of Ravensdown Fertiliser Co-operative.
The factory was built by Fletcher Construction for Dominion Fertiliser and opened on February 28, 1931.
It produced 50,000 tonnes of superphosphate fertiliser in the early years, but that has now grown to 200,000 tonnes a year for markets throughout the South Island and also Australia.
Works manager Tony Gray said in the past two years eight shipments totalling 100,000 tonnes of superphosphate, the most commonly used fertiliser, had been exported to Ravensdown customers in Australia, and volumes were expected to continue to grow.
The plant employs up 42 people and Mr Gray said several had worked there for more than 30 years.
Chief executive Rodney Green said damage from the Canterbury earthquake in September forced the closure of its Hornby manufacturing works for three months and Ravensbourne made up the shortfall.
Phosphate rock from Clarendon, in South Otago, was now being used in about 15% of Ravensbourne superphosphate fertiliser, supplementing imported phosphate rock.
Mr Green said the company has progressively been renewing the acid production plant and would have spent nearly $10 million when the work was completed later this year.
There are also plans to replace a fertiliser storage shed later this year.
Ravensbourne has also helped shape ownership of the country's fertiliser infrastructure, with plant management in the 1970s initiating a reverse takeover of the much larger Kempthorne Prosser to form Ravensdown Fertiliser Co-operative.
The name came from an amalgamation of the two original manufacturing plants, at Ravensbourne and Seadown, near Timaru.
