What is Lime?
Lime, in the sense of applying it to a lawn, is pulverized limestone or chalk. The main component is calcium carbonate. Lime with a high calcium content is referred to as calcitic lime and has the added benefit of adding calcium to the soil. Some limestone contains a significant amount of magnesium and is referred to as dolomitic lime. Dolomitic lime adds magnesium to the soil and could be used if soil tests indicate a magnesium deficiency.
Pulverized lime is powdery and messy to apply, often causing lime dust to blow everywhere. Pelletized lime is more expensive but is made into dust-free pellets which dissolve with subsequent rains or irrigation.
You may need to add lime to your soil if a soil test indicates a pH level below the optimum of 6.0 or 7.0. Soil pH is a measure of a soils alkalinity or acidity. A soil is acidic, or "sour", if it has a pH below 7.0 (neutral).
Soils can be naturally acidic but can also be acidified over time by natural leaching, the use of some nitrogen based fertilizers, excessive rainfall or irrigation, and acidic water sources.
A pH below 6.0 causes important plant growth nutrients to become "bound up" in the soil making them unavailable to the plant. As a result, the turf can decline including a loss of color, reduced vigor and diminished ability to recover from heat and drought stress.
Is Liming Necessary?
The need to lime will be determined by soil tests. Working towards an ideal pH level will help bring the soil into balance and allow for optimum nutrient uptake.
How Much Lime is Necessary?
Soil tests will indicate the amount of pure calcium carbonate to apply in pounds per thousand square feet. Match the needs of the soil test to the amount of pure calcium carbonate indicated on the bag and apply with a lawn spreader. Results of liming are slow to take affect and it can take four to six years to adequately increase the soil pH.
When Can it be Applied ?
Lime can be applied to a lawn any time of year. It is often done during spring or fall when lawn stresses are minimal and more time is usually available.