Plant as many patches as you can easily reach, tack up all boxes (usually between 10-20). Maximize water and weedkiller in each patch.
On every tick, add (maximize) water. Every other tick, add (maximize) weedkiller. Add a single fertilizer when the fertilizer levels are extremely low. Repeat until the barley is Ready to Harvest. This technique uses an average of 20 weedkiller and 3 fertilizer per patch, and takes an average of 10 minutes to come to full harvest.
While roughly as time-efficient as the normal weedkiller strategy, it is very weedkiller-inefficient. With 3x or 5x Barley harvest, it is more efficient than non-weedkiller methods.
Fruity Dry Beer, Noticable honey flavor:
Fruity Dry Brown Beer. Noticable honey flavor:
Blue's doubtful 1
Blue's doubtful 2