Decomposition cycleअपघटन चक्र

NCERT Fig 12.1 · Class 12 Biology · Chapter 12 · interactive diagram

Parts and their functions

• Plant (producer) (पौधा (उत्पादक)) — Absorbs the released inorganic nutrients; its dead leaves, bark and flowers become detritus.
• Detritus (अपरद) — Dead plant remains (leaves, bark, flowers) and dead remains of animals, including fecal matter — the raw material for decomposition.
• Fragmentation (खंडन) — Detritivores such as the earthworm break detritus into smaller particles.
• Leaching (निक्षालन) — Water-soluble inorganic nutrients go down into the soil horizon.
• Unavailable salts (अनुपलब्ध लवण) — Leached nutrients get precipitated as salts that plants cannot use.
• Catabolism (अपचय) — Bacterial and fungal enzymes degrade detritus into simpler inorganic substances.
• Humification → humus (ह्यूमीकरण → ह्यूमस) — Forms humus: dark, amorphous, highly resistant to microbes, decomposes extremely slowly; colloidal, so it is a reservoir of nutrients.
• Mineralisation (खनिजीकरण) — Some microbes further degrade humus, releasing inorganic nutrients.
• Inorganic nutrients (अकार्बनिक पोषक) — End products: carbon dioxide, water and nutrients — taken up again by plants.

Steps

1. Detritus: dead leaves, bark, flowers, dead animals and fecal matter collect on the soil.
2. Fragmentation: detritivores (earthworm) break it into small particles.
3. Leaching: water-soluble nutrients sink into the soil and become unavailable salts.
4. Catabolism: bacterial and fungal enzymes break detritus into simpler inorganic substances.
5. Humification: dark, slow-decomposing humus builds up — a nutrient reservoir.
6. Mineralisation: microbes degrade humus and release inorganic nutrients.
7. Plants absorb the nutrients — the cycle continues.

Original diagram drawn by Simple Learning Hub, based on NCERT Fig 12.1. Report a mistake