The application of lime provides both vital chemical and structural benefits to soil. Their role is pivotal in combating acidity and dispersion issues associated with soil. The addition of lime in the form of calcium carbonate acts to consume hydrogen ions contributing to acidity as well as removing thick cation layers around clay particles ensuring structural stability of the soil.

The most important role of lime is to ameliorate the effect of acidity on soil, thus ensuring that acidity is not the cause of reduced plant health. Hydrogen ions have a disastrous influence on plant growth and can be improved when the carbonate portion of lime reacts with the soil. Oxygen associated with carbonate binds to the hydrogen ions located in the soil to form water. It does so by temporarily forming hydrogen carbonate which then transforms into water and carbon dioxide. Therefore, a large majority of hydrogen ions are converted into water and no longer pose a threat to plant health.

An additional role of lime is the improvement in soil structure and aggregate stability. The calcium portion of lime displaces substances such as hydrogen and aluminum located around the clay particles. Calcium has a smaller molecular weight in comparison to these substances and the area between the clay particles is therefore reduced. The advantage of this occurring is that a reduction in space results in a smaller distance between clay particles and this creates weak bonds of attraction called dipole forces. This binds clay together and although the dipole forces may be very weak, there are quite a number of these attractions overall contributing to make strong cohesive bonds. These strong cohesive bonds form aggregates and ensures that the soil does not deteriorate into its individual sand, silt and clay components as is the case with dispersion, which is not favorable for plant growth.

The chemical and structural effects of lime are essential to soil upholding sufficient means of supporting plant growth. The conversion of hydrogen ions into water and the added benefit of structural stability are key drivers for the use of liming to be undertaken.

Article produced by our Lime and Youth Champion Michael Quin