IN THE FIELD
Many landscape contracts include importing topsoil as a line item. The American Society of Landscape Architects( ASLA) provides guidelines to ensure this topsoil is high quality. It should be free of weeds, disease pathogens, and stones, and meet standards for pH, texture, and organic matter content. If you accept sub-par soil, you’ ll likely spend a lot of money and time improving it later for plants to do well.
Compaction is another topsoil challenge. Even when soil isn’ t hauled away, the traffic of heavy machinery can press the soil so tightly that roots can’ t grow. This often necessitates tilling or subsoiling to loosen the ground before landscaping. Best practices suggest protecting certain areas from traffic and stockpiling topsoil in designated piles during construction to later redistribute it.
Best Practices for Managing Topsoil Sustainably 1. Preserve and Reuse Existing Topsoil On-Site If you’ re involved early in a project, work with builders to stockpile the topsoil before grading begins. Store it in a safe place like a berm or pile, ideally not too tall to avoid smothering the soil microbes, and keep it covered or planted with a temporary cover crop so it doesn’ t blow or wash away.
2. Import High-Quality Topsoil and Amend as Needed In cases where the existing soil is just too poor or gone, importing topsoil is the next option. Always source from a reputable supplier and inspect the material. It should look and smell like healthy soil( dark, earthy, no debris). Check that it meets quality criteria: a neutral to slightly acidic pH( around 5.5 – 7.5 is ideal for most landscapes).
When adding topsoil to a site, about 4 – 6 inches of topsoil is recommended on new lawns to ensure a healthy turf root zone. Garden beds may need even more( 8 – 12 inches) for deep-rooted plants. If you’ re laying sod, don’ t just dust the surface – provide enough depth of good soil for the roots to establish. It also helps to till or loosen the interface between the subsoil and new topsoil, so roots can transition downward and water doesn’ t perch on the compacted layer.
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3. Improve Soil Organically Even after initial installation, encourage practices that build up the topsoil over time. This can include regular top-dressing of beds and lawns with compost, mulching with organic mulches, and planting cover crops or deep-rooted plants in off-seasons to enrich and aerate the soil.
4. Avoid Practices that Strip or Sterilize Soil In maintaining landscapes, be mindful to protect the topsoil you’ ve cultivated. Avoid unnecessary soil removal or aggressive grading that would strip the top layer. Minimize the use of heavy machinery on wet soil to prevent compaction. Also be cautious with chemicals. Overuse of pesticides can harm the beneficial organisms in topsoil, and excessive synthetic fertilizers can degrade soil structure over time.
Simple steps like using board paths for wheelbarrows or temporarily laying plywood for equipment can protect soil during maintenance work. And when adding features like hardscapes, try to disturb as little of the surrounding topsoil as possible, or plan to rehabilitate it afterwards.
Think of it like building a house. You wouldn’ t skimp on the foundation. In the same way, wise landscapers know that investing in soil quality sets the stage for everything else. When you start with a base of rich, well-structured topsoil, plants root deeply and robustly, lawns stay greener with less water, flowers and trees resist pests better, and the whole landscape simply flourishes.
Alex Straughn is general manager at SFI Topsoil. He has been supplying pulverized topsoil to the Chicago area for over two decades. As an active member of Landscape Illinois and Chief Engineer, his commitment to industry standards makes him a trusted resource for construction and landscaping professionals.
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