CSLB C-27 Landscaping ContractorSite Preparation and DrainageMedium
A C-27 contractor is preparing a site for a new lawn installation where the existing soil has poor water infiltration and is prone to waterlogging. To improve the soil's drainage characteristics without significantly altering its composition for planting, which of the following actions is most appropriate?
- AIncorporating gypsum into the topsoil.
- BApplying a heavy dose of nitrogen fertilizer.
- CDeep ripping or subsoiling the area.
- DAdding a thick layer of sand to the surface.
Show answer & explanationAnswer & explanation
Correct answer: C. Deep ripping or subsoiling the area.
Deep ripping or subsoiling helps break up compacted layers below the surface, improving water infiltration and root penetration without changing the soil's chemical composition. Sand alone can worsen drainage in clay, gypsum is for sodic soils, and fertilizer doesn't address compaction or infiltration issues.
Why the other options are wrong
- A. Gypsum (calcium sulfate) is primarily used to improve sodic (high sodium) soils by helping aggregate clay particles, which is different from general poor infiltration due to compaction.
- B. Nitrogen fertilizer is for plant nutrition and does not improve soil physical drainage characteristics or compaction.
- D. Adding sand to clay soil can often create a concrete-like mixture, worsening drainage rather than improving it.
Deep Ripping / Subsoiling
A mechanical process using a subsoiler or ripper to break up compacted soil layers below the surface, improving drainage and root growth.
- Addresses subsurface compaction.
- Enhances water infiltration and aeration.
- Does not alter soil chemical composition.
Memory trick: Break the Blockage, Let it Flow.