What is manure ? How does green manure differ from biofertilizers?

Hint: The manure is rich in nitrogen, phosphorus, and potassium. It is highly rich in organic matter and humus and thus improves the soil fertility.

Complete answer:
Manure is the decomposed form of dead plants and animals, it is used in the soil to increase production. It is a natural form of fertilizer and it is cost-effective. The human and animal excreta is also used as manure.The livestock manure is rich in nitrogen, phosphorus, and potassium.
Manure is highly rich in organic matter and humus and thus improves the soil fertility. These are better in the long run and do not cause any pollution. It is a valuable and renewable resource.
Green manure increases the percentage of organic matter in the soil. The roots of this manures go deep into the soil. These help in the suppression of weeds and the prevention of soil erosion. Green manure is created by leaving uprooted or sown crop parts on a field so that they serve as a soil amendment. The plants used for green manure covers crops grown for this purpose. Typically, they are ploughed under and incorporated into the soil while green or shortly after flowering. Green manure is commonly associated with organic farming and can play an important role in sustainable annual cropping systems. Biofertilzier is a substance containing living microorganisms. It can be used to seed, plant surfaces, or soil. Biofertilizer also improves the supply of primary nutrients like nitrogen, Phosphorus etc. to the host plant, and thereby promotes its growth.

Note: In nature, there are a number of useful soil microorganisms which can help plants to absorb nutrients. Their utility can be enhanced with human intervention by selecting efficient organisms, culturing them and adding them to soils directly or through seeds.