amending clay soil

Asked May 5, 2020, 4:18 PM EDT

What is the scientific explanation for NOT amending clay soil with sand?

Washington County Oregon

1 Response

The issue with clay soils is that the particles are very small. By adding organic matter, you are allowing those clay particles to attach to larger organic particles that will also create spaces for air (roots do need air, in addition to water.) Organic matter is also attractive to microbes and worms that will work their way through the soil and digest the organic matter into other compounds that are bio-available to plants. With sand, clay particles don't have the same affinity to combine into different size particles that would create those channels. You can think of sand as tiny rocks. It takes substantially longer to break down a rock into compounds that are bio-available than it does a piece of wood.