The Benefits of Lime
Fred Newcombe

The benefits of lime are a’plenty!

3 Important Benefits 

  1. improves soil chemistry
  2. encourages beneficial soil biology
  3. helps soil structure

Chemistry of the Soil

The function of lime is to raise the pH of the soil.  Soils with a pH below 7 are deemed acidic, while soils with a pH above 7 are deemed alkaline. In the Northeast, soils tend to be acidic and become more alkaline as you move west.  A pH of 5.0 is ten times more acidic than pH of 6.0; while a pH of 4.0 is a hundred times more acidic than that of pH of 6.0.  Turf grass grows best in soil with a pH of 6.5 – 6.8.  Soils in this range encourage root growth and make more nutrients available to the grass.  Soils with pH 4.0 – 5.0 tend to be similar to those of our forests.  As such, they are more conducive to growing white pines and oaks than turf grass.

Biology of the Soil

Microbial activity is affected by pH. More acidic soils tend to be fungal dominant.  Soils that are in the 6.5 – 6.8 range tend to be more balanced between fungal and bacterial activity. Encouraging this microbial activity contributes to the availability of nitrogen, sulfur, and phosphorus in the soil. Earthworms are also affected by pH and need the pH to be near neutral for their sticky slime. The slime has several purposes, including: allowing the earthworm to breathe through its skin, acting as a lubricant, forming soil aggregates, and facilitating worm burrowing.  

Structure of the Soil

Formation of soil aggregates helps to improve the soil’s structure.  The addition of calcium through the liming process also helps improve soil structure.  Calcium and magnesium stabilize soil aggregates via the formation of organic matter – clay bridges.  Aggregate stability increases soil porosity and tilth. 

Different Kinds of Lime 

  1. Ground and pelleted: Pelletized lime is slightly more expensive than ground but not as dusty, doesn’t present inhalation concerns, is easier to spread, doesn’t cover the lawn in white dust, and is faster acting. 
  2. Standard and high: High efficiency lime is more expensive than standard lime. Although, high efficiency lime requires 1/5th the amount of product, therefore saving in labor. It is ground finer and as a result faster acting. These benefits tend to outweigh the additional material costs.
  3. Dolomitic and Calcitic: The calcium to magnesium ratio on the soil test dictates whether to use dolomitic or calcitic lime. Dolomitic lime contains magnesium and calcium, while calcitic lime is primarily calcium. Both calcium and magnesium are nutrients needed by grass but most lawns in the East are deficient in calcium, therefore requiring calcitic lime.