Making your own compost tea — free fertiliser

Fill a 200L drum with water, hang a hessian bag with 20kg of mature compost in it, add a handful of molasses, and bubble air through it with a cheap aquarium pump for 24 hours. Strain and spray on leaves or drench the soil. My tomato yields went up 15% when I started doing this fortnightly. Total cost: almost nothing. The microbes do the work.