A question often asked is, "When do I apply lime, why do I apply it, and how much?" Also asked, "Is lime a good fertilizer?"

Lime consists of limestone rock that has been ground to a very fine particle size. Lime is composed mostly of calcium but some lime also contains a considerable amount of magnesium and is called dolomite lime. Other types of liming materials are hydrated or slaked lime and burned or quick lime. These materials are not recommended for use on turf grass.

Lime is not a fertilizer. However, it makes and keeps plant food available for growth. The addition of lime to the soil chemically reduces the amount of acid in the soil. When soils are acid (sour), there is an abundance of iron and aluminum present. These two elements combine with phosphorus to form insoluble iron and aluminum phosphates. When this happens the plants cannot use the phosphorus.

Reducing or eliminating soil acid also increases the desirable bacteria in the soil. These bacteria are responsible for decomposing fertilizer and soil organic matter releasing nitrogen, which is used by plants. Bacteria also break down lawn clippings that form thatch. When thatch forms, lawns become thin and weak because air, water and nutrients cannot penetrate the roots. Proper liming increases bacterial activity and helps reduce the thatch problem.

Reducing the soil acid also reduces the incidence of disease in plants and turf grass. Most plant diseases result from infection by fungi. Many of these fungi are most active in strongly acid soil. Sufficient liming will reduce the activity of these fungi. While it will not prevent diseases, it will reduce the severity of the infection.

The only way to determine how much lime your soil needs is by a soil test. A soil test kit can be purchased from the county's Penn State Cooperative Extension office for $9.

It is advisable, if you are doing a large area, that pelleted lime be used. Pelleted lime flows readily through both drop and spinner type spreaders. It is not dusty like the non-pelleted type. Most pelleted lime available in our area is the dolomite type and the magnesium content is beneficial to most of our soils which are magnesium deficient. Do not use hydrated lime or burned lime when liming an established lawn. Both can burn turf.

When preparing a garden or seeding a new lawn, incorporate the lime into six inches or more of the soil. If liming an existing lawn it can be applied anytime of the year. Late fall is the ideal time.