📋 In This Article
Green manure is the practice of growing crops specifically to dig them into the soil while still green. It's one of the most effective, lowest-cost ways to build soil fertility without buying any inputs.
How Green Manures Work
Leguminous green manures (dhaincha, cowpea, sunn hemp) host nitrogen-fixing bacteria in their root nodules that capture atmospheric nitrogen and store it in the soil. When dug in, they release this nitrogen slowly — equivalent to adding 40–80 kg of nitrogen per hectare for free.
Best Green Manures for India
These species are widely available as seeds in India.
- Dhaincha (Sesbania bispinosa) — fastest growing, excellent for waterlogged soil
- Cowpea (Lobia) — drought-tolerant, also edible
- Sunn Hemp (Crotalaria) — tall, excellent nitrogen fixer
- Mustard/Sarson — great for disease suppression, digests quickly
- Rye and Oats — cold-season options for North India hills
Cover Cropping for Weed Suppression
A dense cover crop outcompetes weeds, protects soil from erosion, and maintains soil moisture during fallow periods between main crops. Buckwheat smothers weeds in just 4 weeks. Squash and pumpkin grown as cover crops suppress weeds with their large leaves while producing food.
Timing and Incorporation
Sow green manures 6–8 weeks before you plan to plant your main crop. Dig them in when they're 30–45 cm tall and just beginning to flower — this is when their nitrogen content and moisture is highest. Water well and wait 2–3 weeks before planting into the enriched bed.
Conclusion
One season of green manuring can transform depleted, compacted soil into a productive, living medium. It's the cheapest and most ecologically sound soil-building method available.