The Ruakura campus in Hamilton would shed 15 positions - 11 technicians and four scientists - while positions at the Lincoln campus, near Christchurch, would be reduced by 19, 10 of them scientists.
At Invermay, six positions would go, while four new ones would be created there, along with six at Ruakura, eight at Grasslands and nine at Lincoln.
Mr Richardson said nearly 100 submissions had been received on the proposal, and said the changes were "consistent with our science strategy and shifts in sector need and R&D investment".
AgResearch was "not completely stopping" research in any particular area, he said.
"I'm confident that we are focused on areas of growth and demand and will continue to deliver to meet the needs of the sector."
"Now we've made decisions, supporting the affected staff is our first priority. This is hard for our people and we will be doing all we can to assist them.
"This will take some months to work through."
Waikato University professor of agribusiness Jacqueline Rowarth, who personally knows many of the affected staff, was frustrated at the news.
"It's just another concern about how science is valued in New Zealand."
Professor Rowarth was particularly worried to hear the cuts had come in the greenhouse gas and field work areas, pointing out how a new OECD report had just given New Zealand a poor rating for greenhouse gas emissions.
"And we are saying we don't need research on it? It just seems to me that people haven't thought this through, because the most important thing for the environment - and the economy - is actually testing ideas in the field to ensure they work."
When announcing the changes last month, AgResearch chairman Sam Robinson said declining R&D investment in some areas had meant the organisation was left facing a significant and ongoing funding challenge in those areas.
While both private sector and Government revenue was increasing in other areas, AgResearch's net science revenue was forecast to be $5.3 million less for the coming financial year.
The institute had also recently won $11 million in new projects from the MBIE contestable fund, but this hadn't fully offset the decline in other areas.