Simulation · Biology · Class 12
Decomposition of a bag of leaf litter
From the lesson Decomposition in Ecosystem. Change the values and watch what happens.
Decomposition of a bag of leaf litterBiology · Class 12
The idea behind it
NCERT §12.3
- Decomposers break complex organic matter down into inorganic substances such as carbon dioxide, water and nutrients. This is decomposition.
- The earthworm is called the farmer's friend because it helps break down organic matter and loosens the soil.
- Detritus, the raw material, is made of dead plant remains (leaves, bark, flowers) and dead animal remains, including fecal matter.
- Fragmentation: detritivores such as the earthworm break detritus into smaller particles.
- Leaching: water-soluble inorganic nutrients move down into the soil horizon and are precipitated as unavailable salts.
- Catabolism: enzymes of bacteria and fungi break detritus down to simpler inorganic compounds. These three steps run at the same time on the detritus.
- Humification forms humus, a dark, amorphous substance that resists microbes and decomposes very slowly. Being colloidal, it acts as a nutrient reservoir.
- Mineralisation: some microbes degrade the humus further and release inorganic nutrients.
- Decomposition mostly needs oxygen. It is slower when detritus is rich in lignin and chitin, and faster when it is rich in nitrogen and water-soluble substances such as sugars.
- Of the climatic factors, temperature and soil moisture matter most, acting through soil microbes. Warm, moist conditions speed it up; low temperature and anaerobiosis slow it, so organic matter builds up.