Answer:
a. overtillage can increase the rate of humus decomposition.
Step-by-step explanation:
One way in which overtillage can harm soil is by increasing the rate of humus decomposition. Humus is the organic matter in soil that is formed by the decomposition of plant and animal residues. It is an important component of soil, as it helps to improve soil structure, increase soil fertility, and support the growth of healthy plants. However, excessive tilling can disrupt the structure of the soil and expose humus to air and water, which can speed up its decomposition. This can lead to a decline in soil fertility and a reduction in the ability of the soil to support plant growth.