The Bio Brief

The substances added to the soil to provide nutrients for healthy plant growth are called manure and fertilisers.

Plants need nutrients such as nitrogen, phosphorus, and potassium for proper growth. When farmers grow crops repeatedly in the same field without leaving it empty (fallow), the nutrients in the soil get depleted. As a result, plants become weak and yield decreases. To restore soil nutrients, farmers add manure or fertilisers. This process is called manuring.

Continuous cropping

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Loss of soil nutrients

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Weak plants & low yield

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Manuring needed

Manure

Manure is an organic substance obtained from the decomposition of plant and animal wastes.

Preparation of Manure

• Plant and animal waste is collected in pits
• Microorganisms decompose the waste
• The decomposed matter is used as manure

Plant & animal waste

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Decomposition by microbes

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Organic manure

Example: Vermicomposting (using earthworms)

Advantages of Manure

• Improves soil texture
• Increases water-holding capacity
• Makes soil porous (better air exchange)
• Increases friendly microorganisms
• Replenishes soil nutrients naturally

Fertilisers

Fertilisers are chemical substances rich in specific nutrients. They are manufactured in factories and provide nutrients quickly to plants.

Examples of Fertilisers

• Urea
• Ammonium sulphate
• Super phosphate
• Potash
• NPK (Nitrogen, Phosphorus, Potassium)

Effects of Fertilisers

• Increase crop yield (wheat, rice, maize)
• Excessive use:
  • Reduces soil fertility
  • Causes water pollution
  • Kills useful soil organisms

Crop Rotation

Another method of restoring soil nutrients is crop rotation.

• Different crops are grown alternately in the same field
• Leguminous plants (peas, gram, beans) are grown to increase nitrogen in soil

Leguminous crop

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Rhizobium bacteria

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Nitrogen fixation

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Improved soil fertility

Rhizobium bacteria live in the root nodules of leguminous plants and fix atmospheric nitrogen.

Differences Between Manure and Fertilisers

Manure	Fertilisers
Organic substance	Chemical substance
Made from plant and animal waste	Manufactured in factories
Improves soil structure	Does not improve soil structure
Releases nutrients slowly	Provides nutrients quickly
Increases microbes in soil	Reduces useful microbes if overused
Environment-friendly	Causes soil and water pollution
Increases water-holding capacity	Does not increase water-holding capacity
Long-term benefit	Short-term benefit

Why Manure is Better Than Fertilisers

• Improves soil fertility naturally
• Maintains ecological balance
• Prevents soil degradation
• Supports sustainable agriculture

 Summary

Healthy soil

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Use manure + limited fertilisers

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Proper crop rotation

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Better yield & soil fertility