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Topsoil vs. fill dirt: what each one is for
One grows grass. The other fills holes. Mixing them up is how people end up with a bare patch that never takes.
ME3 Junk Solutions ·
The quick difference
Topsoil is the top layer of soil, the part plants actually live in. Utah State University Extension defines it as the A horizon only. It's darker than the soil below because it holds more organic matter.
Below that is subsoil. USU Extension says subsoil layers have more clay, salts and lime than topsoil, and that makes them a poor substitute for topsoil. A lot of fill dirt is this kind of material.
Fill is about shape, not growth. The University of Wisconsin's Recycled Materials Resource Center describes a fill as earthen material placed and compacted to fill a hole or a low spot. Good fill packs down well and is free of roots, branches, stumps, metal and trash.
When you want fill dirt
Use fill when the goal is to raise or level ground and keep it there. Common jobs:
Ask what's in the fill before it's dumped. Fill from a dig site can carry chunks of concrete, roots or trash, and RMRC's guidance is that fill should be free of that kind of material. Junk buried under a slab can settle later. Clean fill packed in thin layers holds up better than one deep dump.
Fill is meant to be packed in layers. That's why it works under things. It's also why it's a poor place to grow anything on its own.
- Filling a hole left by a stump grinding, a removed pool or an old footing
- Raising a low spot where water stands after rain
- Building up a pad before a shed, slab or patio
- Backfilling along a foundation or a retaining wall
When you want topsoil
Use topsoil where something needs to grow: new sod, seeded patches, flower beds and garden beds. It's also the right cap over fill. Pack the fill, then finish with a layer of topsoil so roots have something to work with.
For a sense of quantity, the University of Connecticut's home garden office says about 12 cubic yards covers roughly 1,000 square feet at 4 inches deep. If the topsoil you get is low in organic matter, UConn says a typical fix is 2 or 3 inches of organic matter tilled in 6 to 8 inches deep. Compost is the usual choice.
To work out cubic yards for your own space, use the same math as mulch. Our post on how much mulch you need walks through it.
How to check a load
Soil isn't a standard product, and quality varies. Look at what you're getting before it's spread.
- Color and feel: University of Maryland Extension says topsoil should be dark and crumbly with an earthy smell.
- Red flags: UMD says to pass on soil that's very high in sand or clay, smells foul, or has grayish mottling or a chalky, sticky or rough feel.
- Trash and rock: UConn says topsoil should be free of trash and debris, and screened topsoil should have no rocks bigger than 3 inches across.
- Weeds and salt: USU Extension says to look for soil free of noxious weeds and weed seeds, and to check for white salt crust on the surface.
- A soil test: UConn suggests testing new topsoil to learn its lime and fertilizer needs and its texture.
A word on Brazos County dirt
What's already under your yard depends on where you live. The Handbook of Texas describes Brazos County soils as alluvial to sandy. The northern third of the county sits in the Blackland Prairie, and the rest is Post Oak Savannah.
The Texas A&M Forest Service says Post Oak Savannah bottomland soils run from clay loam to clay, while the uplands are sandy loam or sand. So a yard near a creek bottom and a yard up on a sandy rise can need very different help. Clay holds water and drains slowly. Sand drains fast and dries out. Either way, good topsoil on top gives new grass and beds a better start. If you're not sure what you have, a soil test beats guessing.
Ordering, delivery and clearing the old stuff
ME3 Junk Solutions offers topsoil and fill dirt delivery, along with mulch, compost, sand, gravel and landscape rock, for homeowners, landlords, property managers and contractors around Bryan, College Station, Caldwell, Hearne, Navasota and nearby communities. Call or text what you need, roughly how much, and the address.
Regrading often starts with tearing something out. If an old shed, deck or playset is in the way, see light demolition. If you're hauling dirt, rock or concrete away instead of bringing it in, know that dense material is quoted separately by weight and handling. Pricing explains why.
Want it handled instead?
ME3 Junk Solutions does the lifting, loading and hauling, with one firm price before anything is loaded.