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Timely Tip – Liming

Why is liming required?

The heavy clay soils of the Delaware Valley have a natural tendency to become acidic or “sour”.  Basic soil elements such as calcium, magnesium and potassium are leached from the soil and replaced by hydrogen ions, thereby increasing the acidity of the soil.  Soil pH is a measure of these hydrogen ions present in the soil.  A pH of 7 is neutral; anything below is acidic.  

The problem with acidic soil is that nutrients are not fully available to grass plants in lower pH (acidic) soil.  Fertilizer applied to an acidic soil cannot be fully utilized by the grass.  Soil acidity also decreases the activity of soil micro-organisms, creating less hospitable soil conditions and increasing the build-up of thatch.  Liming will correct soil pH, improving nutrient availability, increasing beneficial soil life and limiting the build-up of thatch.

When should my lawn be limed?
Suitable soil pH in full sun lawns can be maintained in our area by applying limestone on an annual basis.  Shady lawns often benefit from lime twice per year.  Although liming can be done at any time of the year, it is traditionally done in the fall to allow the freeze/thaw cycles of the winter to physically incorporate the lime into the soil.  Aerating at the time of a lime application serves the same purpose. 

Are all lime products the same?
Liming materials differ in their chemical composition, neutralizing value and speed of reaction with the soil.  A pelletized lime with high neutralizing value, while more costly, allows the product to be applied more evenly with no mess.