Q: Someone told me I should add gypsum to my garden soil. What is gypsum, and what are the benefits of adding it to my garden?
A: Gypsum is a soft white or gray mineral consisting of hydrated calcium sulfate and is used in many ways, one of which is in plaster. It is used to decompact clay soil in the western U.S., where the soil composition is different from Indiana. (See www.agry.purdue.edu/ turf/tips/2009/04172009 _gypsum.html.)
Instead of using gypsum to decompact clay soil in our part of the country, it is recommended that the compacted soil be amended with compost, aged cow or horse manure (in spring), fresh manure (in fall) and sphagnum peat moss.
Sphagnum peat moss comes in bales at most garden centers and is a dry peat, which is used extensively to amend and lighten soils. It is used in seed starting material, and even as mulch that helps hold in moisture when used in vegetable gardens and in containers. It also acidifies the soil and is an excellent additive to use around acid-loving plants, such as blueberries, hydrangeas, azaleas and rhododendrons..
All of these amendments, when tilled in, will greatly improve the soil’s structure and nutrition. Amendments can also be added to the top of compacted clay soil, such as in an established lawn, around trees and other areas where you cannot safely use a tiller.
Begin the process by aerating the lawn or soil around the root system of trees and established shrubs. You can purchase devices such as a spike aerator or a pair of aerator shoes. These work well if you live in the city and have a small area to work with. You can rent a gas or electric driven aerator from many hardware stores and Lowe’s to do the job on larger landscapes.
After opening the compressed soil, spread the amendments on the lawn — even mix grass seed in the soil mixture — water well and see your lawn grasses improve. Opening the soil and piling on amendments under and around trees and shrubs can make a huge difference in their health and growth as well.
Q: I have been told by several people that I need to add lime to my garden soil. I’m not sure why or if I should do that. Hopefully you can help.
A: The soil in Allen County is mostly neutral, meaning it has a pH of 7 or slightly below, which is about perfect for most plants. So before adding lime, have your soil tested. You can have this done for a small fee through the Allen County office of the Purdue Cooperative Extension, 4001 Crescent Ave.
Here is an excellent discussion on adding lime to lawns from Ohio State University — http://ohioline.osu.edu/hyg-fact/4000/4026.html.
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