Table of Contents
Green Manuring
What is Green Manuring?
- The practice of incorporating fresh green plant material into the soil to enhance its fertility and structure.
- Green manure crops are grown and then ploughed under or incorporated into the soil while still green or after flowering
Prevalence and Significance
- Widely practiced in rice-growing states like Andhra Pradesh, Uttar Pradesh, Karnataka, Punjab, and Odisha.
- A 40-50 day old green manure crop can supply up to 80-100 kg of nitrogen per hectare.
- Common green manure legumes include dhaincha, sunhemp, cowpea, mung bean, cluster bean, and berseem.
- Kharif season green manures like dhaincha, sunhemp, mung bean, and cluster bean can contribute 8-21 tons of green matter and 42-95 kg of nitrogen per hectare.
Types of Green Manuring
- Green Leaf Manuring a. Involves collecting green leaves, twigs, and plant parts from trees, shrubs, and herbs growing in wastelands, field bunds, degraded lands, and nearby forests. b. These green materials are turned into or mixed with the soil 15-30 days before sowing the main crop, depending on their tenderness.
- In-situ Green Manuring (On-farm Green Manure or Legume Green Manuring) a. Short-duration legume crops are grown and buried in the same field when they reach 60-80 days after sowing. b. Dhaincha and sunhemp are superior green manures due to their higher biomass production and better nutrient composition compared to food legumes.
Techniques for Effective Green Manuring
Timing is a crucial factor for maximizing benefits of green mauring:
a. Right time for growing the green manure crop.
b. Right time for incorporating it into the soil.
c. Allowing sufficient time for decomposition.
Bio-fertilizers
What are Bio-fertilizers?
- Substances containing living microorganisms that colonize the rhizosphere or plant interior when applied to seeds, plant surfaces, or soil.
- Promote plant growth by increasing the supply or availability of primary nutrients to the host plant.
- Natural fertilizers made from microbial inoculants of bacteria, algae, and fungi.
- Help build up soil micro-flora and improve soil health.
Types of Bio-fertilizers
- Bacterial Bio-fertilizers a. Symbiotic Nitrogen Fixers: Rhizobium, Azospirillum spp. b. Free-living Nitrogen Fixers: Azotobacter, Klebsiella, etc.
- Algal Bio-fertilizers a. Blue-Green Algae (BGA) in association with Azolla b. Anabaena, Nostoc, Oscillatoria
- Phosphate Solubilizing Bacteria: Pseudomonas, Bacillus megaterium
- Fungal Bio-fertilizers: Vesicular-Arbuscular Mycorrhizae (VAM)
Bacterial Bio-fertilizers
- Live bacterial cells used as bio-fertilizers.
- Possess the unique nif gene, enabling them to fix atmospheric nitrogen.
- Work under two conditions: a. Symbiotically: Form nodules in plant roots for nitrogen fixation. b. Free-living (non-symbiotic): Fix atmospheric nitrogen without forming associations.
Application Methods for Bio-fertilizers
- Seed Treatment a. Most common method for all types of inoculants. b. Effective and economical. c. Seeds are first coated with Rhizobium, Azotobacter, or Azospirillum, followed by a layer of phosphate-solubilizing microorganisms (PSM).
- Root Dipping a. Used for applying Azospirillum to paddy or vegetable plants. b. Azospirillum is mixed with water, and the plant roots are dipped for at least 30 minutes before sowing.
- Soil Application a. PSM is applied to the soil at a rate of 2 kg per acre. b. Mix PSM with 400-600 kg of cow dung and rock phosphate (if available).
Precautions for Using Bio-fertilizers
- Store bio-fertilizer packets in a cool, dry place away from direct sunlight and heat.
- Use the right combination of bio-fertilizers for specific crops.
- Rhizobium is crop-specific, so use the appropriate strain.
- Do not mix bio-fertilizers with chemical fertilizers or pesticides.
Advantages of Bio-fertilizers
- Stimulate plant growth by secreting growth hormones.
- Sustain soil health and improve soil texture, structure, and water-holding capacity.
- Replace 25-30% of chemical fertilizers.
- Renewable source of nutrients.
- Increase crop yields by 10-40%.
- Solubilize and mobilize nutrients in the soil.
- Eco-friendly, non-polluting, and cost-effective.
Disadvantages of Bio-fertilizers
- Require special care for long-term storage as they contain living microorganisms.
- Lose effectiveness if contaminated by other microorganisms or if the wrong strain is used.
- Lose effectiveness in excessively hot or dry soil conditions.
Recycling Organic Residues:
What are Organic Residues?
A variety of organic materials, including crop residues (straw, husk, forest litter), animal wastes (dung, urine, bones), guano, city or household residues, oil cakes, by-products of food and sugar industries, pond silt, marine wastes, seaweeds, and human habitation wastes.
Crop Residues
- Two major components: a. Harvest refuse (straw, stubbles, haulms of different crops) b. Process wastes (nut shells, oil cakes, maize cobs, bajra cobs, sorghum cobs)
- Defined as “the non-economic plant parts left in the field after harvest and remains generated from packing sheds or discarded during crop processing.”
Benefits of Recycling Organic Residues
- Supply essential plant nutrients.
- Improve soil properties.
- Protect the soil from erosion hazards.
- Reduce residue accumulation at production sites.
- Provide employment and income opportunities.
- Enhance environmental qualities.
Techniques for Effective Green Manuring
Timing is a crucial factor for maximizing benefits of green mauring:
a. Right time for growing the green manure crop.
b. Right time for incorporating it into the soil.
c. Allowing sufficient time for decomposition.
