Crop rotation
Crop → predecessors, successors, return period
✓ Good predecessors
after legumes, mustard, pumpkin; good after peas
✗ Bad predecessors
not after barley/wheat (root rots)
Return to field
repeat not earlier than 2 yrs
Rules: don't repeat same family, alternate deep/shallow roots, cereals↔legumes↔industrial. Sunflower dries soil to 1–1.5 m.