CSLB C-27 Landscaping ContractorSite Preparation and DrainageMedium
A C-27 contractor is preparing a site for a new planting bed on a moderately sloped area. The soil analysis indicates high acidity (low pH). Which amendment would be most effective to raise the pH to a level suitable for most landscape plants?
- AElemental Sulfur
- BDolomitic Lime
- CPeat Moss
- DGypsum
Show answer & explanationAnswer & explanation
Correct answer: B. Dolomitic Lime
Dolomitic lime (calcium magnesium carbonate) is the most effective and commonly used amendment to raise soil pH (reduce acidity) for general landscape plants. It provides both calcium and magnesium, which are beneficial plant nutrients, while neutralizing soil acidity.
Why the other options are wrong
- A. Elemental sulfur is used to *lower* soil pH (increase acidity), which is the opposite of what is needed here.
- C. Peat moss is an organic amendment that generally *lowers* soil pH slightly or keeps it acidic, making it unsuitable for this purpose.
- D. Gypsum (calcium sulfate) is used to improve soil structure, especially in sodic soils, and add calcium, but it has little to no effect on soil pH.
Soil pH Adjustment (Raising)
The process of increasing the pH of acidic soil to make it more alkaline or neutral, suitable for plant growth.
- Utilizes alkaline amendments.
- Dolomitic lime is a common choice.
- Provides calcium and magnesium.
- Application rate depends on soil test results.
Memory trick: Lime Lifts Low pH, Sulfur Sinks It.