Onions take a lot of potassium and nitrogen from the soil and alkalize it, but they destroy pathogenic microflora.
After this, you can plant almost any crop.
Anastasia Kovrizhnykh, an expert of the online publication Belnovosti, agronomist and landscape designer, talks about the five best options.
The best option is carrots. They release phytoncides that destroy the onion fly.
Secondly, beetroot. It grows well on neutral and slightly alkaline soils and does not require a lot of nitrogen.
Thirdly, legumes. They accumulate nitrogen in their root nodules, thereby restoring the soil depleted by onions.
Also growing well after onions are pumpkins (pumpkins, squash, pattypan squash, cucumbers) and nightshades (potatoes, tomatoes, eggplants, peppers).
Earlier, the expert told how to cure cucumbers from bacteriosis.