Gypsum and Lime for the Lawn

Gypsum

• Gypsum has been a long used fertilizer for landscapes. It is obtained from the saltwater deposits in Michigan and other places in the world. The material is 22 percent calcium, third in importance after nitrogen and potassium for grass. A total of 188,000 tons are used annually in lawns and gardens, cite Paul Boadway Tukey and Neil Newman in "The Organic Lawn Care Manual."

Use Suggestions

• Gypsum is used in soils with high sodium levels. This is usually in coastal areas, Southwest desert regions and in areas where sodium is naturally found in soil. Sodium is harmful to soil structure with its poor water-penetrating ability causing buildup of hard soil particles. The addition of gypsum helps reverse this process. A soil test determines sodium amount and percentage of clay and this determines required amounts of gypsum. Spread the material even on soil and work into the top 6 to 8 inches.

Lime

• Lime's primary use is raising the pH of acidic soils. Raising soil pH levels is important since a number of nutrients, such as nitrogen, sulfur, potassium, phosphorus, magnesium, calcium and molybdenum, are unavailable to grasses growing in acidic soils. This lowers grass resistance to cultural stresses, such as drought, traffic and heat, and increases susceptibility to disease and pests. The recommended soil pH for lawns ranges between 6.0 and 7.0.

Use Suggestions

• A soil test establishes lime requirements. The most used lime for the lawns includes limestone, agricultural lime or dolomite. The use of ordinary garden lime is not recommended for lawns. Apply lime only when indicated by soil test of when grass display visible signs of lime deficiency such as thinning, sparse grass, loss of color and sudden growth of sheep sorrel, woodrush or moss in the grass.