Last updated on October 23rd, 2023 at 08:58 pm
Are you thinking about liming your garden or not? Or perhaps you have already limed it and now want to know how lime affects the soil?
In either case, you’ve come to the right place, because I’ll explain the effect of lime in the soil and what happens to the soil when you lime it.
Lime has a versatile effect in the soil: first, it neutralizes acidity and increases the pH value. This increases crumb formation in the soil, which, among other things, improves aeration, water storage capacity and conductivity of the soil, and ultimately root growth. In addition, lime increases biological activity, i.e. the activity of soil organisms, in the soil, which leads to a better supply of nutrients and water to the plants.
How does lime work in the soil?
Lime is a very versatile raw material and, in addition to its colloquial name, is also known as calcium carbonate or carbonic acid lime.
Calcium carbonate is a chemical compound and consists of the three elements carbon, oxygen and calcium with the molecular formula CaCO3.
The effect of lime in the soil is multidimensional, meaning that lime has a multifaceted influence on soil properties, affecting the soil chemically as well as physically and ultimately biologically.
Chemical effect of lime
Lime increases the soil pH when it comes into contact with acid or an acidic soil.
More specifically, the chemical compound of calcium carbonate (CaCO3) dissolves in the soil when it comes into contact with hydrogen (H+), which acts as a strong acid. This results in the formation of calcium (Ca2), carbon dioxide (CO2) and water (H2O).
Example of the chemical action of lime in soil: CaCO3 + 2 H+ -> Ca2 + CO2 + H2O
In addition to the neutralizing effect of lime thus raising the pH value, the leaching of harmful substances such as aluminum or manganese in the soil is also prevented.
Physical effect of lime
The chemical reaction of lime with acid in the soil released calcium ions (Ca2+).
These calcium ions have the property to combine with humus or clay particles that are in the soil and act as a “glue” or bridge.
That is, after the soil is neutralized, lime physically acts in the soil as a connector, linking various soil particles of humus and clay and creating larger soil crumbs.
The formation of larger or coarser soil crumbs by lime in the soil has the following advantages:
More and larger pores are created in the soil
More and larger pores improve aeration, water holding capacity and water conductivity of the soil
Also, during heavy rain, surface runoff is reduced because water can percolate faster and more water can be absorbed into the soil
Finally, plant root growth is improved because there is more air, water and voids to grow in
Biological effect of lime
Both the chemical and physical effect of lime in the soil also have a positive impact on the biological effect.
This is because lime in the soil has a very positive effect on biological activity. This describes how high the activity of soil organisms, microorganisms and other microorganisms in the soil is.
If the soil is too acidic, the biological activity of the soil organisms is restricted. If the pH increases, for example by adding lime, the activity of the soil organisms is also increased.
Higher biological activity in combination with improved soil structure increases biodiversity and improves the supply of nutrients and water to plants.
What are the advantages of liming the soil?
Liming the soil has a whole range of benefits, which I have listed below:
Increasing or stabilizing the soil pH, thus preventing soil acidification.
Creation of larger, coarser-grained soil crumbs from humus and clay
Creation of more and larger pores in the soil
Improved aeration, water storage capacity and water conductivity of the soil
Reduction of surface runoff, as rainwater can infiltrate the soil more quickly and is better distributed
Finally, plant root growth is improved as there is more air, water and voids to grow in
Inhibits the growth of weeds by balancing pH levels
Protects the garden from siltation by lime improving soil structure or creating fine crumbly soil
Improves heat storage in the soil so that it warms up more quickly in spring, for example.
How does lime affect the soil pH?
By adding lime, acid is neutralized and thus the pH of the soil is increased.
Depending on the amount of lime added, the increase in pH differs, but the process in the soil is always the same:
Calcium carbonate (colloquially lime) reacts with the acid in the soil.
This reaction produces gaseous carbon dioxide, water and calcium
The calcium combines with the water as well as with oxygen from the air, resulting in alkaline calcium hydroxide, which raises the pH of the soil
Is lime good for the soil?
The addition of lime is not only very beneficial for Central European soils, but also absolutely necessary because otherwise the soils acidify in the long term.
Europe, Austria and Switzerland have a Central European climate that causes the soil to slowly acidify.
Every year lime, more precisely about 6-7kg per 100 m² (0,01 ha), is washed out of the soils whereby the pH-value slowly but steadily decreases.
Thus, lime is very good for the soil and increases the pH value, which mainly improves the soil structures:
Lime increases the formation of crumbs in the soil from humus and clay.
Due to larger soil crumbs, aeration, water storage capacity and conductivity in the soil is improved
Thus, lime also reduces soil silting and surface runoff
Is lime good for plants?
Lime has a very positive effect on plants that like neutral or rather calcareous (alkaline) soil. These include boxwoods, tomatoes or azaleas.
However, plants that like a more neutral to acidic soil, such as blueberries, hydrangeas or rhododendrons, usually do not benefit from liming unless the pH would drop into an overly acidic range.
Primarily, lime improves soil structures, but this also has a very beneficial effect on plant growth:
Lime improves or loosens soil structure, which improves plant root growth because there is more air, water and voids to grow in
Lime balances the pH, inhibiting weed growth and allowing vegetables to grow undisturbed as nutrients and water are not consumed by weeds.
Lime improves the heat storage in the soil so that it warms up faster in spring, for example, and thus seedlings, saplings or young plants grow better.