Certified Professional Horticulturist (CPH) Practice Exam

Composting is an ______________ process requiring a constant supply of Oxygen.

1. Oxygenizing

2. Aerobic

3. Anaerobic

4. Facultative

The correct answer is: Aerobic

The correct choice is "aerobic," as composting is an aerobic process, meaning it requires oxygen for microorganisms to effectively break down organic matter. During aerobic composting, various bacteria and fungi utilize oxygen to decompose materials, resulting in a faster breakdown of organic materials into compost compared to anaerobic processes. Oxygen plays a critical role in the decomposition process by promoting the growth of aerobic microorganisms, which are more efficient than their anaerobic counterparts. This not only helps in speeding up the composting process but also leads to the production of a compost that is richer in nutrients and has fewer odors. In contrast, anaerobic processes do not require oxygen and can often lead to the production of unpleasant smells and a slower decomposition process. "Facultative" refers to organisms that can function in both aerobic and anaerobic conditions, but this is not specifically how composting is characterized, as the most beneficial and common method is strictly aerobic, relying on a continual supply of oxygen. Thus, the term "aerobic" best captures the essence of the composting process described.