Page 39 - SCERT Kerala State Syllabus 8th Standard Basic Science Textbooks English Medium Part 1_Neat

Indicators

• What is the role of microorganisms in ensuring the natural
availability of elements in the soil?
• What is the need of testing the soil?

• Why does the application of fertilizers become essential for
better crop yield?
Farmers use different kinds of fertilizers in order to increase the
fertility of the soil. You are familiar with different kinds of
fertilizers such as chemical fertilizers, bio-fertilizers,green leaf
manure etc. Now observe the picture below.

What is a
microbial
fertilizer?

Read the pamphlet Geethu got from the Agricultural Officer when
she sought to clarify certain doubts.

Microbes that provide fertilizers

Microbial fertilizers are substances that contain microorganisms which help
to increase the fertility of soil. The presence of microbes enables increase in the
soil factors which are essential for plant growth. Bacteria like Rhizobium,
Azotobacter, Azospirillum and aquatic plants like Azolla can be used to increase
nitrogen content in the soil.
Things to be taken care of
• ensure the availability of biofertilizers in the soil.

• proper irrigation should be provided.
• chemical fertilizers or chemical pesticides should not be used.
Microorganisms can exist in soil only if these precautions are taken.

38 Basic Science VIII