Tips for purchasing the best topsoil

By Dawn Pettinelli - UConn Home & Garden Education Center
Home & Garden - posted Wed., Apr. 11, 2012
- Contributed Photo

A common misconception when buying topsoil is that the soil will be a dark, friable, fertile loam able to cure any or all garden ills. In reality, there are no legal marketing standards for topsoil.

Soil, the foundation of our landscape, is composed of sand, silt and clay, with varying amounts of organic material, water and air mixed in. It is not a uniform material and may exhibit differences in composition or properties, even over distances of a few feet. Typically, when problems arise in the home landscape, soils bear the brunt of the blame when often environmental, cultural or biological factors may be causing the plant’s demise.

So how do you know when to buy new topsoil and when to either amend your present soil or adjust your cultural techniques? There is no hard and fast answer. As a rule, purchased topsoil is necessary to adjust the grade of the landscape, to create raised beds or possibly to cover existing soils having high lead levels. If your soil is infertile, acidic or difficult to work, the additions of limestone, organic matter and nutrients will do much to improve its condition. Locally-obtained topsoil is often not too different from what you presently have on site. Bagged topsoil may be pH balanced and well fortified with organic matter and/or nutrients, but it would be an expensive way to fill in a large area.

“Topsoil” is defined as the uppermost layer of soil. It is usually darker in color than the subsoil below because of the accumulation of organic matter. The term “loam,” on the other hand, is a soil textural classification. Texture refers to the relative amounts of sand, silt and clay-sized particles occurring in a soil. By USDA definition, a loam is any soil with between 7 and 27 percent clay, less than 52 percent sand, and the rest silt.

Before you purchase any topsoil, it is a good idea to visually inspect the stockpiled soil. It should be free from glass, trash and other debris. Feel it to check the texture.

Often, a preconceived notion when purchasing topsoil is: the darker, the better. While an increase in darkness is often associated with an increase in organic matter, soils which are very dark or grayish may have been dredged from swampy areas. These soils are usually very finely textured, acidic, lacking in nutrients, and best avoided.

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