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What is Lime?
First, what is lime? Agricultural lime comes in many forms, but generally consists of a compound made up of calcium or calcium and magnesium. The most common form of this compound comes in a finely ground powder or pellet, and is made of ground limestone which is almost pure calcium carbonate. Burnt and hydrated lime are other types which act much faster than ground lime, but can also be hazardous to handle and are often more difficult to apply.
Benefits of Lime
Lime is applied to the soil of home lawns for the purpose of increasing the pH of the soil. Applications of lime to neutralize the acidic condition and raise the soil pH above 6.0 can increase the availability of these nutrients, making it easier to maintain the quality of the lawn. Over-application of liming products can cause the development of alkaline soil conditions.
How to determine if lime is necessary
You wouldn’t take an antacid if you didn’t have heartburn would you? Then why apply lime to a lawn that doesn’t need it? So how do we know if the soil in our lawns needs this acid relief? The only sure way is by getting your soil tested by a state or commercial soil testing laboratory. Many times homeowners will buy soil test kits found at many garden centers. These do-it-yourself kits may tell you that your soil needs lime, but they don’t tell you how much. The reason is that individual soils can differ greatly in the amount of lime required to raise the pH to a specified level between 6.0 and 7.0. Over-applying lime is just as bad as having an acidic soil since this then pushes your soil into the alkali category which requires its own special solutions to correct. Professional soil tests on the other hand will not only let you know if liming is necessary, but will let you know how much lime you need to apply.
How much lime should be applied?
Most soil test reports will indicate the lime requirements in per 1000 square feet. To calculate how much lime product to apply find the percentage under calcium carbonate equivalent label on your bag. Then find the liming requirement on your soil test report. Using these two numbers, perform the following calculation:
Liming Requirement (from soil test) Calcium Carbonate Equivalent = Amount of Product/Acre or /1000 Square Feet
If this amount exceeds the values in the table below, the amount recommended for your lawn should be divided in half and applied at two different times during the year.
When is the best time to apply lime?
Lime is a treatment for your soil, not your grass, and the best time to get at the soil is when there's no grass on top of it. If you're starting a new lawn, make sure to test your soil and add lime before you plant. Once your lawn is in place, the best time to lime is in the spring or the fall. But beware: lime has the potential to burn your grass, especially on hot days. The turf should be irrigated after application in order to wash any lime off of the turfgrass leaves.
Watch Out For Treatment Overload
It may be tempting to spread fertilizer and lime and herbicide all at once -- why wait? The simple answer is because too many chemicals at once can damage your lawn. If you want to mend your soil with lime and fertilize your lawn, wait at least a week between treatments.
Are All Liming Materials The Same?
As indicated in the table below, all liming materials are not the same. They can differ in price, safety, ease of application, calcium carbonate equivalent and rate at which they work. Note that gypsum (calcium sulfate) is not included in this table. Gypsum will change soil pH very little, if at all, and should never be considered as a liming material.
Any effective liming material will be finely ground. This is important because the rate at which limestone raises pH increases with the fineness of the particles. Plus, limestone affects only the small volume of soil surrounding each limestone particle. A given volume of limestone contains more particles if it is finely ground and thus affects more soil than coarser limestone. Many states govern the sizes of limestone particles in pelletized lime and agricultural ground limestone.
Which liming material is best?
The most widely used liming materials for turfgrass areas consist of carbonates of calcium or magnesium. These include agricultural ground limestone, pelletized limestone and flowable limestone. Of these three, agricultural ground limestone is the type turf managers use most widely. Dolomitic limestone, another ground-limestone product, comes from ground rock containing calcium carbonate and magnesium carbonate and is appropriate where a soil test shows low pH and deficient levels of magnesium.
Pelletized limestone is ground agricultural limestone that has been aggregated into larger particles to facilitate spreading and reduce dust. A water-soluble substance that quickly dissolves when wet binds the aggregates together.
Flowable limestone is available for use on turf when you need to use a liquid application. Although liquid applications are dust-free and uniform, you only can apply relatively small amounts at one time, and lime spray suspensions may be abrasive to sprayer parts.
Some turf managers occasionally use other liming materials, such as hydrated (slaked) lime and burned lime (quicklime), on turfgrass areas. These products are made from hydroxides and oxides of calcium and magnesium. They can raise the pH more quickly than carbonate forms but tend to be more powdery and harder to handle.
Liming Materials and Their Characteristics
rate of application
These are approximate values and will vary with the purity of the individual product.
Maximum rate in pounds of product/1000 square feet. Multiply by 44 for rate in pounds/acre.