Green manuring is the plowing under or soil incorporation of any green manure crops while they are green or soon after they flower. Green manures are forage or leguminous crops that are grown for their leafy materials needed for soil conservation.
Advantages of green manuring
1. Improves the soil fertility
2. Add nutrients and organic matters
3. Improves the soil structure
4. Improves soil aeration
5. Helps control insect/mite pests, nematodes, and diseases
6. Helps control weeds
7. Promotes habitat for natural enemies
8. Increases soil’s biodiversity by stimulating the growth of beneficial microbes and other soil organisms
Green manure crops
| Green manure crops | Seeding rate (kg/ha) | Green biomass (t/ha) | Dry biomass (t/ha) | Nitrogen content (%) | Nitrogen (kg/ha) | When to incorporate in the soil? (DAP) |
| Azolla | 50-90 | 8-10 | 1.8-3 | 52 | 35 | |
| Cowpea | 40 | 9-10 | 3-4 | 1.4-1.5 | 140-150 | 40-60 |
| Lablab | 7-18 | 5-7 | 220 | 45-60 | ||
| Mustard | 5-12 | 3.5 | 21-37 | |||
| Pigeon pea | 45-67 | 9-10 | 5-7 | 45-60 | ||
| Sesbania | 20-90 | 1.5-4 | 4.3 | 250-360 | 45-50 | |
| Soybean | 30-56 | 5-7.4 | 310 | 45-60 | ||
| Sun hemp | 35-40 | 5-19 | 5.5-6 | 1.7 | 108 | 50-60 |
| Sweet clover | 30-40 | 12 | 6 | 2 | 40-50 |
Criteria for the selection of green manure crops
1. Fast growing
2. Produce abundant and succulent tops
3. Well adapted to the local condition
4. Can fix nitrogen in the soil
Reminders
1. Broadcast or sow the seeds after harvest
2. Cut the greens after flowering and plow them under
3. Sow or transplant the next crops 1-2 weeks after the incorporation of the green manure
