Topsoil is often used to fill holes, low spots, and other depressions in lawns and yards. It provides an easy and inexpensive way to level out uneven areas and prepare them for seeding or laying new sod. Topsoil contains organic matter that is beneficial for establishing grass and plants. However, there are some important factors to consider when using topsoil as a fill material. Proper soil selection, preparation, and installation techniques are key to ensuring successful results.
What is Topsoil?
Topsoil is the uppermost layer of soil that contains most of the organic matter and microorganisms. It is usually darker and richer than the subsoil underneath. Good quality topsoil is loose, crumbly, and drains well while still retaining some moisture. Here are some key characteristics of topsoil:
- Contains 2% to 10% organic matter such as decayed leaves, roots, and other plant residues
- Has a loamy texture – the ideal blend of sand, silt, and clay
- pH between 6.0 to 7.0
- Free of weeds, rocks, debris, toxic substances, or other undesirable materials
- Rich brown or black color from organic content
- Supports healthy populations of microorganisms, earthworms, and other beneficial organisms
These features allow topsoil to provide nutrients, anchor roots, retain moisture, and facilitate air exchange for plant growth.
Benefits of Using Topsoil as Fill Dirt
Adding topsoil is generally an effective way to fill small depressions and level out a bumpy lawn. Here are some of the benefits of using topsoil as fill material:
- Contains nutrients – The organic matter in topsoil supplies essential macro and micronutrients that grass and plants need to thrive. This can help new vegetation establish quickly in filled areas.
- Good drainage – The loose, friable structure allows water to permeate while still retaining some moisture and nutrients.
- Easy to work with – Topsoil is relatively lightweight and can be easily spread, graded, and shaped by hand or with basic tools.
- Holds seed and sod – The fine texture creates good contact between grass seed or sod and the soil underneath to anchor roots.
- Inexpensive and accessible – Topsoil is one of the most affordable and readily available fill materials for small residential projects.
- Provides equilibrium for roots – The organic content creates a balanced environment for roots to access air, moisture, and nutrients.
Using existing topsoil to fill holes in the yard means you don’t have to purchase and transport large quantities of new material. It’s simple to blend with surrounding soil.
How Much Topsoil Do I Need?
Determining how much topsoil you need for filling holes or low areas depends on the size and depth of the depressions. Here are some guidelines for estimating topsoil needs:
- Measure the length, width, and depth of each hole or depression.
- Calculate the cubic feet of space that needs to be filled by multiplying length x width x depth.
- Divide cubic feet by 27 to convert to cubic yards if needed.
- Allow for an extra 10-20% more soil than the measured volume to account for settling and compaction.
- One cubic yard of topsoil covers about 324 square feet at a 1-inch depth.
- Bulk topsoil is often sold by the cubic yard or half-yard.
It may take some trial and error to determine exactly how much is needed. Start conservatively and check the filled holes for low spots that may need more soil. Having a small surplus of topsoil on hand makes it easier to top up as needed.
Sourcing Good Quality Topsoil
Not all topsoil is created equal when it comes to filling holes and depressions. Here are some tips for sourcing topsoil that contains the right properties for your project:
- Check with local landscape supply stores, nurseries, or soil companies for bulk deliveries.
- Ask for a sandy loam or loam topsoil.
- Inspect samples if possible – it should be loose, crumbly soil free of weeds and odor.
- Ideal pH is between 6.0-7.0.
- Avoid clay-based soils which don’t drain well.
- Store topsoil in a dry area or cover with a tarp until ready to use.
- Have soil tested if concerned about toxicity or contamination.
Purchasing quality screened topsoil from a reputable supplier gives the best results, but can be more expensive. On-site soil may work if it has good texture and organic matter content.
Prepping the Holes and Depressions
Proper site preparation is key to ensure topsoil can be compacted and integrated with surrounding soil. Here are some tips:
- Remove dead vegetation, rocks, debris from holes.
- Loosen compacted soil at bottom with a spade or tiller if hard-packed.
- Break up sides of hole vertically to increase surface area for soil contact.
- Moisten dry soil but avoid soggy, muddy conditions.
- Apply supplemental fertilizer or compost if nutrient levels are low.
- Delineate edges with markers if filling over a large area.
Preparing the holes helps the fresh topsoil blend and bond with existing soil. This provides stability and facilitates rapid rooting and establishment.
Filling Techniques and Best Practices
Proper filling and grading procedures for topsoil include:
- Fill holes in lifts or layers no more than 6 inches deep.
- Use a rake to spread soil evenly and remove large clumps.
- Tamp down each layer with a hand tamper, roller, or plate compactor.
- Ensure adequate compaction but avoid excessive compacting which restricts root growth.
- Leave soil mound slightly higher than surrounding grade to allow for settling.
- Feather out edges of topsoil for a seamless transition.
- Slope graded soil away from foundations or structures for drainage.
- Apply starter fertilizer if needed to stimulate turf establishment.
Filling in multiple thin layers allows thorough compaction as you build up. The finished grade should be smooth, uniform, and direct water away from buildings and paved areas.
Establishing Turfgrass in Filled Areas
Once topsoil is installed, take steps to establish grass or sod:
- Seed warm season grass in spring through early summer.
- Cool season grass seeding is best in fall.
- Opt for quick-establishing grass varieties.
- Use straw as mulch to conserve moisture for seeds.
- Lay sod in a staggered bricklike pattern.
- Roll sod to ensure solid contact with soil.
- Water newly seeded or sodded areas frequently until rooted.
- Avoid heavy traffic until turf is well established.
Proper watering and maintenance helps new grass thrive. Spot seed bare or sparse areas for full uniform coverage.
Pitfalls to Avoid When Filling with Topsoil
There are a few things to keep in mind to avoid problems when filling holes with topsoil:
- Don’t add too much material at once without compacting in layers.
- Avoid using low-quality subsoil with little organic matter.
- Prevent soil from drying out completely before turf goes down.
- Don’t over-compact soil to the point it restricts seed germination.
- Avoid creating low spots that collect standing water.
- Don’t install cold season grass heading into hot summer months.
Patience is also needed – it can take a full growing season or longer for the grass to knit the area together into a cohesive lawn.
Other Options Beyond Topsoil
While topsoil works well for minor depressions up to about 6 inches deep, other fill materials are better suited for larger-scale lawn grading or holes deeper than a foot. Options to consider include:
- Sandy loam soil
- Silt, clay, gravel
- Sand
- Pulverized bark, compost
- Masonry sand
- Peat moss or coir
- Crushed stone dust
- Polymers and absorbents
These can be used alone or blended with topsoil depending on the needs of the project. It’s also possible to purchase soil blends customized for lawns and gardens.
For excessively steep slopes or areas with poor drainage, retaining walls, French drains, swales, or re-grading may be required. Consulting a professional landscaper is recommended for major grading work.
Maintenance Tips for Filled Areas
Proper maintenance helps ensure filled regions knit into the surrounding lawn:
- Spot seed thin or bare areas as needed.
- Top-dress low spots with extra topsoil.
- Aerate compacted soils in filled holes.
- Adjust irrigation to provide consistent moisture.
- Watch for erosion issues and redirect runoff.
- Re-seed once or twice per year until fully established.
Avoid heavy traffic and mowing until grass is mature – at least 2 to 3 mowings. Patience and attentive care leads to the best outcome.
Conclusion
Topsoil provides an accessible and affordable way to fill minor depressions and holes in your yard. With careful selection of quality topsoil along with proper preparation and installation techniques, you can resurface uneven areas to create a smooth, lush lawn. Focus on blending with surrounding soil, proper grading, establishing grass quickly, and maintaining optimal growing conditions. For large-scale lawn leveling or deep holes, it may be better to consider sand, gravel, or other fill materials. But for small fixes, topsoil is usually the top choice.