How do I stop weeds from coming back every season in my field?

Weeds keep coming back because the soil holds a large weed seed bank, a reserve of weed seeds built up over years, and each weed left to flower and set seed adds thousands more to it, so the only way to win long term is to steadily run the seed bank down while stopping it from refilling. The core idea is: never let weeds seed. Remove or kill weeds, including the escapes that survive a spray, before they flower and shed seed, because those survivors refill the bank for years. Use clean, certified crop seed and well-decomposed manure so you do not import fresh weed seeds, and clean machinery and irrigation channels that carry seed from field to field. Rotate crops and the matching herbicide systems so no one weed species can specialise on your field. Keep a dense, competitive, timely-sown crop that shades weeds out. Use the stale seedbed before sowing to germinate and kill a flush in advance. Over a few seasons of not letting weeds seed, plus crop rotation and good crop competition, the seed bank shrinks and the yearly weed pressure drops a lot. Use only herbicides recommended for your crops at label dose, rotate modes of action, and ask your KVK to help build a multi-year plan suited to your fields.