Certified Professional Horticulturist (CPH) Practice Exam

Which method can effectively improve soil structure and aeration over time?

1. Overwatering

2. Regular fertilization

3. Adding compost or organic matter

4. Using chemical stabilizers

The correct answer is: Adding compost or organic matter

Adding compost or organic matter is an effective method for improving soil structure and aeration over time. When compost or organic matter is incorporated into the soil, it enhances the physical properties of the soil, improving its tilth, making it easier to work with. This practice introduces organic materials that increase soil porosity, allowing for better air movement and water infiltration. Furthermore, the decomposition process of organic matter adds beneficial microorganisms and nutrient content, promoting a healthy soil ecosystem which is vital for plant growth. In addition to enhancing aeration, compost helps in creating aggregates in the soil. These aggregates are clumps of soil that form when soil particles bind together, which improves drainage and reduces compaction. Over time, this contributes to a more well-structured soil that can hold moisture and nutrients more effectively, thereby supporting plant health and growth. The other methods listed do not lead to long-lasting improvements in soil structure and aeration. Overwatering can lead to compaction and poor aeration, while regular fertilization primarily provides nutrients but does not necessarily enhance soil structure. Using chemical stabilizers might offer some short-term benefits but often lacks the holistic, ongoing improvements to soil health that organic matter provides.