There is an irritation system inside the barn.
It can be used to spread any chemicals you might need during the night.
This is the low-spoiler guide for "The irrigation system in the barn" puzzle in Don't Escape: 4 Days to Survive. Unlike in normal walkthrough, you get gradual hints on how to solve the puzzle. Click the big button below to see your first hint. If the hint contains a spoiler, you will be warned about it before clicking.