Organic manures and fertilizers

This page includes some important information about organic manures and fertilizers, and answer key of MCQ on manures and fertilizers.

Answer key: MCQ on Manures and Fertilizers

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Organic manures

What is manure?

Originally, the word ‘manure’ denotes materials like cattle and other bulky natural substances that is applied to land with the object of increasing the production of crops. It may be an organic substance or a chemical compound. So in a general way, it is a substance containing plant nutrients.

Here, organics are known as manure and inorganics are called as fertilizer.

What are the advantages of manuring?

The advantages of manuring are as follows:

  • Manure supplies plant nutrients.
  • It improves the physical properties of soil like soil structure.
  • Increases nutrient availability.
  • Improves water holding capacity.
  • Provides food for microorganisms.
  • Prevents loss of nutrients by leaching and soil erosion.
  • Provides buffering action in soil reaction.


On the basis of concentration of nutrients, it can be grouped in to two categories:

  • Bulky OM.
  • Concentrated OM.

What is compost?

Compost is the process of reducing vegetables and animal refuse except dung to a quickly utilisable condition for improving and maintaining soil fertility and decomposed material is called compost.


01: Bulky OM

FYM, compost and green manure are the most important and widely used bulky OM. They contain small percentage of nutrients and are applied in large quantity.

02: Composition of FYM

  • Nitrogen 0.5%
  • Phosphorus 0.2%
  • Potash 0.5%

03: Generally 10-20 tonnes well decomposed FYM per hectare is applied, but more than 20 tonnes FYM per hectare is applied in case of vegetable, at least 15 days before the sowing to avoid immobilisation of N.

04: FYM is the most important OM in India. It is very common in Indian agriculture. One tonne of cattle dung can supply 2.95 kg of nitrogen, 1.59 kg of phosphorus, and 2.95 kg of potash.

05: Nutrient contents of some green manure fresh are as follows


Manures description

06: See description under compost.

07: Compost

  • Compost is well decomposed organic matter.
  • Superphosphate is used for making supercompost.
  • We prepare azo compost by using N fixing bacteria.

08: Azo compost is the cheapest source of N among all organic manures. It contains 1.5% N.

09: Composition of Farm-Compost


10: Composition of Farm-Compost prepared by Bangalore method


11: Fire fanging

There is profuse fungal growth on the surface of moist manure giving it an ashy grey appearance. It is referred to as fire fanging.

12: Sewage and sludge

  • Solid portion is sewage.
  • Liquid portion is sludge.

13: Green manuring gives 60-80 kg N/ha on an average. Green manuring crops having stem nodulation are as follows

  • Sesbania rostrata.
  • Aeschynomene afraspera.

14: The concentrated OMs have higher nutrients than bulky OM.

15: Olicakes and N content

Cotton cake6.6%
Castor cake5.5-5.8%

Inorganic manures

16: Examples of straight fertilizers

  • Urea.
  • Ammonium sulphate.

17: DAP is an example of complex or compound fertilizer.

18: Ammonium nitrate is the most hygroscopic fertilizer.

19: Equivalent acidity

The amount of CaCO3 required to neutralise the acid caused by application of acidic fertilizers in the soil. For example, 100 kg (NH4)2SO4 produces acidity which needs 110 kg of CaCO3 to neutralise it.

Equivalent acidity of some fertilizers are as follows:

  • Anhydrous ammonia: 148.
  • NH4Cl: 128.
  • (NH4)2SO4: 110.
  • Urea: 80-84.

20: Equivalent basicity

It is the residual basicity which is caused by the application of basic fertilizers. Equivalent basicity is expressed in terms of CaCO3 equivalent of basic residue left by a fertilizer material.

The equivalent basicity of some fertilizers are as follows

  • CaCN: 63.
  • NaNO3: 29.
  • KNO3: 29.
  • Ca(NO3)2: 21.

21: Ca % in secondary fertilizers

  • Gypsum: 29.2%.
  • Rock phosphate: 33.1%.
  • Single super phosphate: 19.5%.

22: Citrate soluble but water insoluble phosphatic fertilizers

  • Dicalcium phosphate.
  • Basic slag.
  • Rhemania phosphate.

23: CAN is the abbreviation of Calcium Ammonium Nitrate.

24: Can is also known as Kisan Khad.

25: The trade name of urea ammonium phosphate is GROMOR.


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