Trees for Clay & Gypsum
- Gypsum specimens should not be added to soil.Jupiterimages/Photos.com/Getty Images
Adding gypsum (calcium sulfate) to clay soil to break it up is a traditional garden practice, but there is a growing movement to discourage it because it's not effective in breaking down some kinds of clay soils. An equally strong consideration is that adding gypsum can cause negative effects to the overall ecosystem. Gypsum has never been scientifically linked to an improvement in soil fertility or pH balance. - A tree's nutrients can be impacted by gypsum.Jupiterimages/Photos.com/Getty Images
Gypsum can heighten leaching of aluminum that contaminates watersheds, and it can have a negative effect on the tree's ability to secure certain nutrients from the soil, such as iron and manganese. Furthermore, any positive effect it might have on breaking up the clay soil is short-lived, lasting just a few months at most. - Willow trees will grow in clay soil.Photos.com/Photos.com/Getty Images
To grow trees in clay soil, plant late in the autumn when the soil is driest. Add plenty of organic matter, such as manure and composted bark, to break down the clay, and continue this process for several years. Don't add gravel, however, since that will actually make the soil less fertile. The same can be said for working fine sands into the soil. - Raised garden beds provide a way around clay soil problems.Karl Weatherly/Digital Vision/Getty Images
There are some geographic areas, however, where gypsum is sometimes effective in breaking down clay soil. This occurs in the coastal Southeast and extremely dry Southwest part of the United States. That's because the soil in both these locations is low in calcium and high in salt, so gypsum helps bring the clay soil parts together to form larger pore spaces. In these areas, however, many gardeners avoid the potential harm of adding gypsum by creating raised beds full of compost and topsoil, and planting trees in these special areas.
