"They have to be the right trees, in the right place, for the right reason. It's not just about numbers."
Cotton has been planting trees on his coastal Whanganui land for 15 years and had been inspired to ramp that up by going to open days and seeing what others have managed to do without losing production.
There had also been interest in planting in the Ruapehu District where Cotton and councillor Bruce Rollinson had spent a lot of time.
Trees planted this winter were done with Government funding in partnership with Horizons' Sustainable Land Use Initiative.
They were at least 800,000 mānuka seedlings, plus pines, natives and 30,000 poplar poles.
The most erodible land was targeted - mainly Ruapehu, Whanganui, Tararua and Pohangina hill country.
Who gets the benefit from the planting depends on the agreement with the landowner.
The percentage of forestry earnings going to Horizons will depend on costs and forecast earnings. Carbon credits (NZUs) usually stay with the landowner.
"It's very much a business decision, planting forestry. The numbers have to stack up for both parties. There has to be a reasonable return for Horizons, because we are using public money," Cotton said.
The council is applying for more Government money to plant more trees on erodible land next winter.
"If farmers have any interest in knowing what we can do for them on erosion, they should contact their local Horizons office and the field representative will be happy to come out and give them a no-obligation overview of the programmes available," Cotton said.