Crop Rotation

Crop rotation is the practice of growing different types of crops on the same piece of land in a planned sequence across different seasons or years.

Example: Season 1 → Wheat | Season 2 → Mustard | Season 3 → Legume (moong, chana) | repeat

1. Soil Nutrient Management

• Different crops absorb different nutrients → prevents depletion of one nutrient
• Legumes (beans, peas, gram) host Rhizobium bacteria in root nodules → fix atmospheric N₂ into ammonium (natural fertiliser)
• After legume crop, soil is nitrogen-enriched for the next cereal crop (wheat, rice)

2. Pest and Disease Control

• Same crop every season = same pest population builds up
• Rotation breaks the pest life cycle — pests dependent on one crop find no host the next season
• Reduces need for pesticides

3. Weed Control

• Different crops have different growing patterns → different weeds thrive
• Rotation prevents any one weed from dominating the field

4. Soil Structure

• Deep-rooted crops break up compacted soil layers
• Shallow-rooted crops allow topsoil to recover
• Different root systems create different pore structures → better water retention

Classic 3-year rotation: Cereal → Legume → Root vegetable (or fallow)

A legume crop is ploughed back into the soil while still green → decomposes → adds nitrogen and organic matter. Example: sunhemp (Crotalaria juncea) grown and ploughed in before the main crop.

• Key benefit: nitrogen enrichment via legume-Rhizobium partnership
• Rotation = sustainable agriculture (reduces chemical input)
• Alternating deep-rooted and shallow-rooted crops for soil structure
• Green manuring as an extension of the same principle

1. Why is a legume grown between two cereal crops?
2. How does crop rotation help control pests?
3. What is green manuring?
4. Name two Kharif and two Rabi crops.
5. Stretch: Why would a farmer growing the same crop every year need more fertiliser each year?