The public was told of the threat in March and formula was taken off supermarket shelves and held securely to prevent contamination.
In what became known as Operation Concord, 60 people were considered of significant interest and approached to be interviewed by police.
More than 2600 people were considered over the course of the investigation, which cost police $3 million, Police Commissioner Mike Bush revealed when the man was arrested in October.
Police said they believed the arrested man acted alone and no one else has been charged.
However, several company names have also been suppressed by the court.
According to court documents, the man "threatened expressly to endanger the safety of any person, namely infants, by releasing infant milk formula into the Chinese market contaminated with traces of 1080, with intent to cause Federated Farmers Incorporated to act in accordance with the will of [the man] to cause Federated Farmers to pressure the New Zealand Government to stop the use of 1080 in New Zealand".
The second charge names Fonterra as the victim of the threat.
Blackmail is punishable by up to 14 years jail.
The man was remanded in custody until February.
The controversial pesticide has been continued to be used by the Department of Conservation for pest control.