Back to: MICROBIOLOGY 100 LEVEL
Welcome to class!
Hello, brilliant star! I’m always so proud to have you in class. Your hunger for knowledge lights up every topic we learn. Today, we’re going to talk about something super important to all life on Earth—Nitrogen Fixation and Decomposition. These two natural processes, powered by microbes, quietly support our food, farming, and the whole environment. Let’s understand how these tiny organisms do such mighty work!
Nitrogen Fixation, Decomposition
Nitrogen Fixation
Nitrogen is one of the most important elements living things need. Plants use it to grow strong leaves, roots, and stems. But here’s the twist—plants cannot take nitrogen directly from the air, even though it makes up about 78% of the atmosphere. So how do they get it? That’s where nitrogen-fixing bacteria come in.
What is Nitrogen Fixation?
Nitrogen fixation is the process where certain microbes convert nitrogen gas (N₂) from the air into forms like ammonia (NH₃) or nitrates (NO₃⁻), which plants can absorb and use.
Types of Nitrogen-Fixing Microbes:
Free-living bacteria like Azotobacter and Clostridium live in the soil and fix nitrogen on their own.
Symbiotic bacteria like Rhizobium live inside root nodules of legume plants (beans, groundnuts, soybeans) and fix nitrogen while receiving shelter and nutrients from the plant.
Why is Nitrogen Fixation Important?
Without nitrogen fixation, plants wouldn’t get the nutrients they need, and farming would be almost impossible without chemical fertilisers. These bacteria are like nature’s free fertiliser makers!
When a farmer plants beans in the soil, she’s not just growing food—she’s also helping to enrich the soil with nitrogen for the next crop, thanks to the Rhizobium bacteria.
Decomposition
Decomposition is the natural process of breaking down dead organisms—like fallen leaves, dead animals, or food waste—into simpler substances.
What is Decomposition?
Microorganisms such as bacteria and fungi feed on dead matter, breaking it down into nutrients that return to the soil. This keeps the environment clean and makes the soil rich.
Stages of Decomposition:
Fresh stage: Microbes start to break down soft tissues.
Bloating stage: Gases build up as bacteria continue breaking down material.
Active decay: The body or material starts to collapse.
Advanced decay: Microbes finish breaking down the matter.
Dry/remains stage: Only bones or dry parts may remain.
Why is Decomposition Important?
It recycles nutrients into the environment.
Prevents waste build-up.
Supports soil health and farming.
Forms compost for natural fertiliser.
If you throw away fruit peels in a compost pit, they slowly rot. What’s happening? Microbes are at work, turning waste into food for the soil.
Summary
- Nitrogen fixation is the process where bacteria convert nitrogen gas into plant-usable forms.
- Rhizobium fixes nitrogen in legume root nodules.
- Decomposition is how microbes break down dead organisms into nutrients.
- Both processes are vital for farming, soil health, and environmental balance.
Evaluation
- What is nitrogen fixation, and why is it important?
- Name one free-living and one symbiotic nitrogen-fixing bacterium.
- What is decomposition?
- Mention two benefits of decomposition in nature.
- How does decomposition help farmers?
You’re truly growing into a science expert! These small but powerful microbial activities show us that nature is full of smart systems. Keep learning with Afrilearn—we’re rooting for you every step of the way!