What type of material is the gardener using when she refers to composted materials?

The gardener’s reference to composted materials primarily points to decomposed organic matter known as humus. Humus is a rich, dark organic material that forms when plant and animal matter decomposes. It is a critical component of healthy soil because it improves soil structure, increases water retention, and enhances nutrient availability for plants. When organic waste such as vegetable scraps, yard waste, and other biodegradable materials are allowed to decompose, they transform into humus through microbial activity, primarily by bacteria and fungi.

This process of decomposition not only recycles nutrients back into the soil but also fosters a rich ecosystem of beneficial microorganisms. Humus plays a key role in supporting plant growth and maintaining soil health, making it an essential product of composting practices utilized by gardeners.

In contrast, the other options focus on different aspects of soil and organisms but do not accurately represent composted materials as directly as humus does. Thus, identifying composted materials with humus reflects a proper understanding of composting and its significance in gardening and environmental health.