Chapter 2 - Bulky & Concentrated manures | Unit I Notes - Fertilizers and Soil Fertility Management

Unit-I Syllabus

Fertilizers and Soil Fertility Management

Chapter 2 - Properties, and methods of preparation of bulky & concentrated manures.

Bulky Manures

Bulky manures are organic materials that are typically low in nutrient concentration, such as FYM, straw, hay, and sawdust. These types of manures are usually applied in large quantities to soil to improve its structure, water holding capacity, and fertility. Bulky manures can take longer to break down and release their nutrients, but they can have long-lasting benefits for soil health.

These manures are typically made from animal waste such as cow, horse, or poultry manure, as well as plant materials such as straw, hay, and leaves. The term "bulky" refers to the high volume of these materials, which can be added to the soil to increase its organic matter content.

a. Farmyard manure

Farmyard manure, which is a combination of decomposed dung and urine of farm animals, along with litter and residual materials from fodder fed to the cattle, is a valuable organic fertiliser.


i. Typically, well-decomposed farmyard manure comprises 0.5 percent N, 0.2 percent P2O5, and 0.5 percent K2O.

ii. Gypsum and superphosphate are common chemicals used to reduce nutrient losses and increase phosphorus content in FYM.

iii. Farmyard manure is particularly effective for vegetable crops such as potatoes, tomatoes, sweet potatoes, carrots, radishes, onions, as well as sugarcane, rice, Napier grass, orchard crops such as oranges, bananas, mango, and plantation crops like coconut.

iv. Not all of the nutrients present in farmyard manure are immediately available, with only about 30 percent of nitrogen, 60 to 70 percent of phosphorus, and 70 percent of potassium being available to the first crop.

Methods of preparation:-

To produce high-quality farmyard manure (FYM), it should be prepared in properly sized pits. The following steps should be taken to prepare FYM properly:

Collecting animal excreta: It is important to collect animal excreta without losing any urine. For this purpose, straw, waste fodder, or crop residues can be spread under the animals to absorb the urine. Paddy straw is especially suitable for this purpose, as it absorbs urine effectively. About 1 kg of straw can absorb approximately 1.5 kg of urine. If there is a solid floor under the animals, approximately 50% of urine can be collected and added to the farm waste with the help of buckets. This reduces the proportion of carbon and nitrogen, making the straw rot faster.

Digging the pit: The dimensions of the pit should be based on the number of animals and the amount of excreta produced. Typically, a 6-7 m long, 1-1.5 m wide, and 3 feet deep pit is sufficient for 3-5 animals. The depth of the pit from one side should be 3 feet and from the other side, it should be 3.5 feet. The pit should be dug in a place where rainwater cannot collect, and ridges should be made around the pit.

Filling the pit: The pit should be filled from the low deep side, up to 1.5 feet high from the ground. Then, a 1.5-2 inches thick soil layer should be added above it. This helps to degrade the seeds of the farm waste and protect the dosage elements from sunlight.

Number of pits: Each farmer should have at least 2-3 pits so that the first pit can be covered after adding soil, and the second pit can be filled. By the time the second pit is filled, the FYM in the first pit will be ready to be added to the field. This ensures a continuous supply of manure for the crops.

b. Composted manure

Composted manure is a type of organic fertiliser made by decomposing organic waste.


i. Farm compost is made from farm waste, such as sugarcane trash, paddy straw, weeds, and other plants.

ii. The average nutrient content of farm compost is 0.5% N, 0.15% P2O5, and 0.5% K2O.

iii. The addition of superphosphate or rock phosphate (10-15 kg/t of raw material) at the initial stage of filling the compost pit can increase the nutrient value of farm compost.

Methods of preparation:

  • Select a location that is at least partially protected from rain.
  • Gather crop residues, animal manure, and other waste materials to the preparation site.
  • Firstly, pile crop and other plant residues (15 cm thick).
  • Next, spread the animal manure to a thickness of about 8 cm followed by a layer of about 3 cm of good soil.
  • Repeat the layering until the compost pile is about 1.5 metres high.
  • Water the pile regularly to maintain sufficient moisture.
  • Turn or mix the pile using a spading fork after three weeks and then again after five weeks.
  • The compost will be ready to harvest in three to four months.

c. Town Compost:

Organic waste collected in towns and cities can be converted into good manure through composting.

Methods of preparation:

Large trenches are constructed away from human habitation, and filled with successive layers of town refuse and soil. It takes about 3 months for decomposition, after which the compost can be used for cultivation.

d. Sewage and Sludge:

In modern urban sanitation systems, human excreta is flushed out with water, creating sewage. The solid portion is called sludge.

Methods of preparation:

Both components undergo preliminary fermentation and oxidation treatments to reduce bacterial contamination and offensive smells.

e. Night Soil

Human excreta, both solid and liquid, is referred to as night soil. It is considered one of the best organic fertilisers as it provides a quick response, especially as a top dressing.


Night soil is rich in nitrogen, phosphorus, and potassium, containing on average 5.5 percent N, 4.0 percent P2O5, and 2.0 percent K2O.

Methods of preparation:

To prepare night soil, farmers cover toilets filled with human waste with soil and leave them for at least two years for the decomposition process to take place. After this, the cover layer of soil is scraped off, and the pits are emptied using spades and hand hoes while wearing gloves and gumboots for protection.

f. Green Manure

Green manuring involves incorporating fresh, undecomposed green plant tissue into the soil to improve soil fertility and physical structure.


i. One ton of well-grown green manure is equivalent to 2.8 to 3.0 tons of farmyard manure (FYM) or 4.5 to 4.7 kg of nitrogen, which is equivalent to 10 kg of urea. Applying 6 t/ha of green tissue can provide 24 to 30 kg N/ha to a rice crop.

ii. Green manure crops can establish and grow quickly.

iii. They are tolerant of adverse climatic conditions, such as drought, waterlogging, high and low temperatures, pests, and diseases.

iv. The crop should have adequate Rhizobium nodulation potential and be an effective nitrogen fixer.

v. The crop should be fast-growing, capable of accumulating sufficient fixed nitrogen in 4-6 weeks, easy to incorporate, and quickly decomposable.

vi. Examples of green manure crops are sunhemp, dhaincha, and lentil.

Green leaf manuring crops include karanj and ipomea.

Methods of preparation:

The green manure crop should be sown at a higher seed rate than usual to produce a good canopy quickly. For example, the usual seed rate for sunn hemp is about 40 to 50 kg per hectare. The crop should be incorporated into the soil when it reaches the flowering stage. Sunhemp is ready for turning in at the age of 7 to 8 weeks, while dhaincha is ready when 5 to 6 weeks old.

After ploughing the material, the soil should be packed (compacted) carefully by suitable implements to ensure proper decomposition. Packing is especially necessary if the soil moisture supply is deficient. For proper decomposition, the crop should be buried deeper in light soils than in heavy ones.

Concentrated Manures

Concentrated manures, on the other hand, are high in nutrient concentration and are usually derived from animal waste, such as poultry litter, pig manure, or cow manure. These types of manures are often applied in smaller quantities and are rich in nitrogen, phosphorus, and potassium, which are essential nutrients for plant growth. Concentrated manures are a type of organic fertiliser that is made by removing the water and other non-nutritive components from animal waste.

Concentrated manures can be used to provide a quick boost of nutrients to plants, but they need to be used carefully to avoid over-fertilizing and causing environmental problems such as eutrophication of water bodies.

Properties and methods of preparation:

a. Poultry manure:


Rich in nitrogen, phosphorus, and potassium.

High levels of calcium and trace elements.

Can have a strong odour.

Can be acidic, with a pH range of 6 to 8.

Methods of preparation:

Collect poultry droppings and bedding material.

Mix the droppings and bedding material to make a compost pile.

Add water to the pile to maintain moisture.

Turn the pile periodically to allow for even decomposition.

After about 6 to 9 months, the compost should be ready to use.

b. Horse manure:


Contains high levels of nitrogen, phosphorus, and potassium.

Can be relatively low in organic matter.

Has a high carbon to nitrogen ratio.

Can be high in weed seeds.

Methods of preparation:

Collect horse droppings and bedding material.

Mix the droppings and bedding material to make a compost pile.

Add water to the pile to maintain moisture.

Turn the pile periodically to allow for even decomposition.

After about 6 to 12 months, the compost should be ready to use.

c. Bat guano:


High in nitrogen, phosphorus, and potassium.

Contains a range of trace elements.

Can have a strong odour.

Can be acidic.

Methods of preparation:

Collect the droppings of bats from their roosts.

Process the guano to remove any impurities.

Dry the guano in the sun or in a drying shed.

Crush the dried guano into a powder or pellets.

Use as a fertiliser.

d. Fish emulsion:


High in nitrogen, phosphorus, and potassium.

Contains trace elements and amino acids.

Has a low carbon to nitrogen ratio.

Can have a strong odour.

Methods of preparation:

Process fish waste to extract the liquid.

Add water and stabilise the pH to make the emulsion.

Use as a liquid fertiliser.

Overall, concentrated manures are a rich source of nutrients and can be prepared by following certain methods depending on the type of manure. These manures, when used properly, can greatly enhance the growth and yield of crops.

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