What fertiliser and irrigation does quinoa need and how do I manage weeds?

Quinoa is a low input crop and over fertilising, especially too much nitrogen, makes it grow leafy, lodge and delay maturity, so keep nutrients moderate and lean on a basal dose with organic manure plus a modest nitrogen split, confirming the exact dose with your KVK for your soil. It is drought tolerant, so it needs only a few light irrigations, typically one after sowing for establishment and one or two at the critical flowering and grain fill stages if there is no rain, while avoiding waterlogging which kills it. Weeds are the real early problem because young quinoa grows slowly and looks similar to some weeds, so do timely manual weeding or hoeing in the first few weeks and sow in lines to make weeding easier. There is no reliable selective herbicide cleared for quinoa here, so do not spray a random weedicide on it. Get the local schedule from your KVK.