A Canadian pension fund manager is emerging as a major force in Australian agriculture with a $2 billion-plus spending spree that now includes a bid for Webster Limited and its extensive portfolio of irrigated farmland and water rights.

The PSP Investments bid values the ASX-listed agribusiness, chaired by one-time waterfront warrior Chris Corrigan, at $854 million including debt, despite Webster struggling to break even this year even though it holds about 150,000 megalitres of water entitlements that underpin its tree nut growing and other businesses.