Biology · Ecosystems · NEET
Humification is one of the steps of decomposition. During humification, the partly decomposed detritus builds up into a dark coloured substance called humus. NCERT says humification leads to the accumulation of humus. It happens in the soil, along with mineralisation.
Humus is a dark coloured, amorphous, colloidal substance. Amorphous means it has no definite shape. Colloidal means its tiny particles stay spread in the soil. Because of these properties, humus can hold and store nutrients.
Humus is still ORGANIC. It is partly broken-down organic matter, not the final inorganic nutrients. The inorganic nutrients (like CO2, water, salts) are released only later, during mineralisation. This is a common NEET trap.
NCERT states humus is highly resistant to microbial action and so it decomposes at an extremely slow rate. Because it breaks down so slowly, humus stays in the soil for a long time and works as a reservoir (store) of nutrients for plants.
Humification makes humus (a dark, colloidal, organic store). Mineralisation is the NEXT step, where some microbes further degrade this humus and release inorganic nutrients into the soil. Simple line: humification stores, mineralisation releases.
Both humification and mineralisation occur in the soil during decomposition. Fragmentation, leaching, catabolism, humification and mineralisation all operate at the same time on the detritus.
Identify the correct statements: A. Detritivores perform fragmentation. B. The humus is further degraded by some microbes during mineralisation. C. Water soluble inorganic nutrients go down into the soil and get precipitated by a process called leaching. D. The detritus food chain begins with living organisms. E. Earthworms break down detritus into smaller particles by a process called catabolism.
Match List I with List II: A. Decomposition B. Detritus C. Mineralisation D. Humification | I. Accumulation of dark coloured amorphous colloidal substance II. Release of inorganic nutrients by the activity of microbes in soil III. Breaking down of complex organic matter into inorganic substances IV. Dead remains of plants and animals including fecal matter
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Humification is the decomposition step that leads to accumulation of humus, a dark coloured, amorphous, colloidal substance in the soil.
Humus is dark coloured, amorphous (no fixed shape) and colloidal. It is highly resistant to microbial action, decomposes very slowly, and acts as a reservoir of nutrients.
No. Humification only forms and stores humus. Inorganic nutrients are released in the next step, mineralisation, when microbes degrade the humus.
Humus is highly resistant to microbes and decomposes at an extremely slow rate. That is why it stays long in the soil and stores nutrients.
It is in Class 12 Biology, chapter Ecosystem, under Decomposition, along with fragmentation, leaching, catabolism and mineralisation.
