How to buy a good bulk topsoil
Growing anything starts with your soil. However, topsoil tends to be an overarching term for a number of products that vary in use and quality. While all have an important use, only some are appropriate for growing plants, lawns, and vegetables.
There are important differences between dirts & soils
Fill Dirt: A low-quality, unscreened dirt that is used to raise the level of the ground.
Screened Dirt: A low-quality dirt that has the larger rocks and debris screened out.
Blended or mixed soil: Created most often by mixing compost with a fill or screened dirt to make it a higher quality, hopefully good enough for growing
Topsoil: While there are a variety of underlying soil types (textures)--sandy, clay, silt, peat, chalk, and loam--all are focused on being high enough quality for growing.
How to find a good bulk topsoil
The best soil is a "loam" because it balances the strengths and weaknesses of the three most basic soil elements: sand, silt, and clay. Here's how to find a good loamy soil.
Check for a dark, brown color, which indicates a nice amount of organic matter. A light or white residue on the surface may indicate lime or salts, which can negatively impact growth. Warning signs: a light color may lack minerals, and; a blue-green or gray could suggest that the soil has been saturated and drained of its nutrients.
Dry: Feel for a crumbly natural and grainy texture, which suggest important minerals in the soil. Warning signs: hard texture suggests lack of organic matter; large clumps suggest too much clay, and; large stones or weed roots suggest poor ingredients and processing.
Wet: Wet a small amount of sand in the palm of your hand. Feel for a balance (rather than domination) of three properties: grittiness suggests sand, stickiness suggests clay, and; smoothness suggests silt.
The soil should smell slightly sweet. Avoid anything that has a rotting, chemical, or otherwise off-putting smell to it.
Ask where the ingredients come from. Most topsoils in the area use "native" dirt--i.e. whatever is dug out of the ground during construction-and have a wide variation in quality. Some native soils are so poor that, even after mixing with compost, will not be sufficient for growing.