Bulky Organic Manures

Definition: Bulky organic manures are materials of plant and animal origin that, when added to soil, improve soil structure by decreasing bulk density and increasing soil volume. They enhance soil aeration, water-holding capacity, and nutrient availability, although they provide nutrients in smaller quantities compared to chemical fertilizers.

Characteristics of Bulky Organic Manures

1. Low Nutrient Concentration: These manures have relatively lower concentrations of plant nutrients compared to chemical fertilizers.
2. Wider C:N and C:S Ratios: The carbon-to-nitrogen (C:N) and carbon-to-sulfur (C:S) ratios are wide, providing energy for soil microorganisms to thrive.
3. Nutrient Availability through Mineralization: The nutrients in organic matter become available to plants only after mineralization, a process where microorganisms break down organic compounds.
4. Combination with Inorganic Fertilizers: A balanced application of organic and inorganic fertilizers ensures sustained soil fertility.

Examples of Bulky Organic Manures

1. Farm Yard Manure (FYM)
2. Composts
3. Green Manures
4. Pouderette
5. Biogas Slurry
6. Sewage or Sludge
7. Molasses
8. Vermicompost

Farm Yard Manure (FYM)

Definition: Farm Yard Manure refers to the physical composition of cattle manure, comprising dung, urine, and bedding material (litter) like hay or straw used for cattle. It is a slow-acting, bulky organic manure with low nutrient content but significant benefits for soil health.

Constituents of FYM

1. Dung: Solid excreta of farm animals, representing undigested portions of feed. Contains digestive juices, tissues from the alimentary canal, and microbial cells. Moisture content: 70–80%.
2. Urine: Liquid excreta of animals, rich in by-products of nitrogen metabolism. Composed of 90% water and small amounts of urea, hippuric acid, and minerals like Ca, Mg, K, and Na.
3. Litter: Bedding material such as straw, leaves, and stems used for cattle. Absorbs urine and contributes carbonaceous matter to facilitate decomposition.

Quality and Composition of FYM

The quality and nutrient composition of FYM vary depending on several factors:

1. Kind of Animal: Different animals produce manure of varying quality. Milch cattle, dry cattle, work cattle, and breeding bulls provide different compositions. Animals with lower feed assimilation produce better-quality manure.
2. Age and Condition of Animal: Growing, pregnant, and lactating animals utilize more nutrients from feed, producing lower-quality manure. Adult animals on light work produce better manure due to higher nutrient excretion.
3. Quality and Quantity of Feed: Protein-rich feeds, like oil cakes, lead to nitrogen-rich manure. Animals fed with concentrated feeds produce better-quality manure compared to those fed with straw and green grass.
4. Kind of Litter Used: The nature of litter significantly affects manure quality. Leguminous hays provide richer manure compared to ordinary straws.
5. Collection of Manure: Proper collection methods prevent nutrient loss, especially nitrogen. Common collection systems include:
   • Byre System: Cattle are kept in sheds with non-absorbent floors and a drainage system for urine collection. This system conserves urine and maintains hygiene.
   • Dry Earth System: The floor is layered with sand, red earth, or loamy soil to absorb urine. Wet layers are removed weekly and stored in manure pits. This method is popular in rural India due to its affordability.
6. Storage of Manure: Storage affects manure quality due to fermentative changes and decomposition. Three common storage methods are:
   • Pit Method (Below Ground Level): Manure is stored in a pit with non-absorbent bottoms and sides. A bund around the pit prevents rainwater runoff. While this method reduces nutrient loss compared to the heap method, exposure to sun and rain can still degrade quality.
   • Heap Method (Above Ground Level): Manure is heaped on the ground, often under tree shade. Dung is covered with urine-soaked litter and a layer of ash or earth to prevent moisture loss. This method is common but leads to significant nutrient losses due to exposure to sun and rain.
   • Covered Pit Method (Best Method): Manure is stored in a pit lined with non-absorbent granite stones. A 1.5-foot bund around the pit prevents surface runoff.The pit is covered with locally available materials like Palmyra leaves. This method effectively controls nutrient loss, ensuring high-quality manure.

Nutrient Composition of FYM: On average, well-prepared FYM contains:

• Nitrogen (N): 0.68%
• Phosphorus (P): 0.5%
• Potassium (K): 1%

Improved Methods of Handling Farm Yard Manure (FYM)

While it is nearly impossible to completely prevent the loss of plant nutrients and organic matter during the handling and storage of FYM, improved methods can significantly reduce these losses. One of the most effective approaches is the Trench Method of Preparing FYM, as recommended by C.N. Acharya.

A) Trench Method of Preparing FYM

Overview: The trench method involves preparing manure in specially dug trenches of appropriate size. This method ensures better decomposition, minimizes nutrient loss, and improves the quality of the final manure.

Trench Dimensions: The recommended size for the trench is: Length: 20 to 25 feet, Breadth: 5 to 6 feet, Depth: 3 to 3.5 feet

Collection and Preparation Process:

• Dry Litter and Refuse: Collect all available dry litter and refuse from the farm and houses. Heap them near the cattle shed for daily use.
• Litter Spreading: Spread portions of litter mixed with earth in the cattle shed every evening. Apply litter at a rate of 2.26 kg per animal. Focus the litter in areas where urine usually drops and soaks into the ground.
• Daily Collection: Every morning, collect the urine-soaked litter and dung. Mix them thoroughly before transporting them to the manure trench.

Trench Filling Process:

• Start filling the trench from one end, covering a 3-foot length daily with the refuse from the cattle shed.
• Continue this process until the trench is filled up to 1.5 to 2 feet above ground level.
• Shape the top into a dome-like structure and plaster it with a mixture of cow dung and soil.

Decomposition Period:

• The manure takes approximately 3 months to decompose properly.
• During this time, the next 3-foot section of the trench is filled with fresh collections.
• Generally, two such trenches are sufficient for handling the waste of 3 to 4 cattle.

Manure Output and Nutrient Enrichment:

• This method can produce about 250-300 cubic feet of manure per animal.
• This amounts to 3 to 5 tons or 10 to 12 cartloads of manure per animal.
• To enrich the manure, add 30 to 40 kg of superphosphate per trench before field application.

Nutrient Content: The final FYM prepared using the trench method contains:

• • Nitrogen (N): 0.7 to 0.8% on a fresh weight basis
  • Nitrogen (N): 1.4 to 1.6% on a dry weight basis