Most Amish farms are organic (not trendy, just 300-year habit). Pesticides cost money. Amish don't spend money unnecessarily.
Methods
Hand weeding (children, 2-3 hours daily in summer). Companion planting (marigolds repel bugs). Crop rotation (breaks pest cycles). Birds (birdhouses on every field). Manure (healthy soil = strong plants).
Does It Work?
Amish yields — 70-80% of industrial. But costs — 30% of industrial. Profit per acre — comparable. And soil after 30 years — alive, not dead.