National is promising a $400 million boost to irrigation and water storage development if re-elected.
Launching the party's agriculture policy at the Tasman District Council this afternoon, Prime Minister John Key announced plans to set up a Crown Water Investment Company to invest in irrigation projects.
Up to $400m from the Future Investment Fund, which draws money from partial asset sales, would be committed to the company.
"The scheme would operate through the Crown being a minority partner, and investing with the expectation of a commercial return on that investment," Mr Key said.
"The intention would be that the stake would be sold off over time."
The funding would first be available in the 2013 Budget, and would continue for the subsequent four years.
The Future Investment Fund is dependent on the Government's planned sales of shares in Air New Zealand and the four state-owned power companies, and Mr Key was today questioned about whether it was fair to commit money from the fund at this stage.
The Prime Minister said he was confident the timetables for the asset sales and the different investments meant money would be available
"If we are the Government post-November 26 then we will be undertaking the mixed-ownership model, and that will allow us to release capital to make investments in other areas."
Agriculture Minister David Carter said the scheme was not about subsidising irrigation to farmers.
"The scheme's being developed showing an economic return so farmers and horticulturists will invest in them," Mr Carter said.
"It is a matter, with the big schemes, of getting them over the line with some investment from iwi, from other infrastructure investors, with the Government there as a catalyst investor in the first place that will get the schemes up and running."