The shocking truth about topsoil
What every homeowner should know about topsoil.
September 17, 2012 - Author: Gretchen Voyle, Michigan State University Extension
Almost every homeowner with any property has said at sometime, “We need to buy some topsoil.” It could be to fill flower beds, build up the vegetable garden or cover sandy or clay soils when putting in a lawn. But do they really know what they are getting?
Myth #1: Topsoil means that it is going to be good, dark and rich soil.
Balloon popper: There is no legal definition of the word topsoil. Technically, it is whatever is on the top. Sight unseen, you could order 5 yards of anything from beach sand to adobe brick material. Always go to look at what you are buying if you are unfamiliar with the soil seller to know what you are purchasing.
Myth #2: Good topsoil is very black.
Balloon popper: Very black soils are not always the best soils. You should be able to feel some grit when you rub a small amount of soil between your thumb and forefinger. This is the mineral portion of the soil, which is critical for plant growth. Those minerals include phosphorus, potassium, calcium, magnesium and many more. The black portion is the organic portion, which is slowly decomposing nitrogen. It’s just like music. It is impossible to write a good song using only one note. The soil should contain both minerals and organic material. It may be very good soil and not deep black.
Myth #3: There are no weed seeds in good topsoil.
Balloon popper: All topsoil comes with weed seeds. There is no way for even the most diligent seller to remove these. If the soil was heated to kill the seeds, it would also kill all the valuable microorganisms in the soil. This sterile disaster would create more problems than it would solve. Soil equals seeds, and when plants appear, they are often plants that you will recognize because they are not currently growing on your property.
Myth #4: All I have to do is spread it over my existing soil and jump back and watch great things happen.
Balloon popper: Topsoil sitting as a completely separate layer on top of the existing soil is going to create drainage and growing problems. When adding soil, it is almost guaranteed to be different from the existing soil. It will create problems for roots growing downward. Roots will stop at the original soil layer, especially if it is denser. To create a natural way for water to drain and moisture to percolate up, it is very important to mix some of the soils together. Add 2 or 3 inches of new soil and till it to mix in. Then, more can be added because you have just created that transitional layer. It is well worth the additional effort.
Myth #5: I don’t have to fertilize when I use topsoil.
Balloon popper: What you have just purchased may be lower in nutrients than what you already own. The seller is providing soil, not fertilizer. Topsoil may provide tiny amounts of nutrients, but don’t avoid soil testing because you think nutrient problems have been resolved.
For information on soil testing, go to www.msusoiltest.com