Irrigation is a technology that can be researched at the Food Proc Ctr in Tech Level 2. It costs 75 Food and 75 Carbon, and makes Farms produce +75 Food. It must be researched before Harvesting Program becomes available.
This technology is essential if the player relies on Farms, saving them from having to replant them quite as often. If the player instead gathers food from hunting, fishing, or Animal Nurseries, it can be ignored.
"Available at the Food Processing Centre, this Tech Level 2 upgrade makes Farms more efficient, allowing them to produce more food before they need to be replanted."
—Manual description