CSLB C-27 Landscaping ContractorSite Preparation and DrainageEasy
A landscape contractor is planning a new planting bed on a site with heavy clay soil. To improve soil structure and aeration, which of the following organic amendments is generally most effective when incorporated into the top 6-8 inches?
- APerlite
- BSand
- CPeat moss
- DCompost
Show answer & explanationAnswer & explanation
Correct answer: D. Compost
Compost is highly effective for improving clay soil structure and aeration due to its rich organic matter content. It helps aggregate clay particles, creating a more porous and workable soil.
Why the other options are wrong
- A. Perlite is primarily used for improving drainage and aeration in potting mixes, not typically for amending large areas of clay soil.
- B. Sand can worsen clay soil by creating a concrete-like mixture if not added in very large quantities (which is impractical).
- C. Peat moss improves water retention and aeration but is less effective than compost for long-term soil structure improvement in heavy clay and has environmental concerns.
Organic Amendment for Clay Soil
Organic amendments, particularly compost, are incorporated into heavy clay soils to improve their structure, aeration, drainage, and workability.
- Compost helps clay particles aggregate, creating larger pore spaces.
- Improves drainage and reduces compaction.
- Increases water-holding capacity and nutrient availability.
- Should be incorporated into the top 6-12 inches of soil.
Memory trick: Clay needs COMPOST to breathe and grow strong.