Factors Affecting Decomposition

What four factors commonly affect the rate of decay?

Temperature, water availability, oxygen availability and the number or type of decomposers.

How does increasing temperature initially affect decay?

It generally increases enzyme activity and microbial growth, speeding up decay.

Why does decay slow at low temperatures?

Enzyme-controlled reactions and microbial growth become slower.

Why can very high temperatures stop decomposition by microorganisms?

Enzymes may denature and microorganisms may die.

Why is moisture necessary for rapid decomposition?

Water is needed for microbial metabolism and enzyme activity.

Why does dry material often decay slowly?

Low water availability limits decomposer activity.

Why can oxygen increase decomposition rate?

Many decomposers use aerobic respiration to release energy.

Why might waterlogged soil have a low decomposition rate?

It often contains little available oxygen, limiting aerobic decomposers.

Why does shredding organic material speed up decomposition?

It increases the surface area available for microbial action.

Why does turning compost speed up decomposition?

It introduces oxygen, supporting aerobic respiration.

Why is compost often warm inside?

Decomposers release energy during respiration, increasing the temperature.

Why can compost become too hot for some microorganisms?

High temperatures can reduce enzyme activity or kill microorganisms.

How can decomposition be investigated experimentally?

Compare the rate of decay under different controlled conditions.

What could be the independent variable in a decomposition investigation?

Temperature, moisture or oxygen availability.

What could be the dependent variable in a decomposition investigation?

Mass loss, gas production or another measure of decay.

Why should the starting mass of organic material be controlled?

To ensure a fair comparison of decomposition rates.

Why should the same type of material be used?

Different materials have different chemical compositions and decay rates.

Why should decomposition experiments be repeated?

To improve reliability and identify anomalies.