In the garden, lime is mainly used to amend the soil, to treat the trunks of fruit trees against parasites and to remove moss from lawns.
What is quicklime?
Quicklime or calcium carbonate comes from the calcination of limestone rocks at 900°C, which produces
a white alkaline powder that
is very reactive to water and dangerous to handle with bare hands. Water added to quicklime releases heat (80°C) and produces slaked lime (calcium hydroxide) which is less corrosive.
These caustic products tend to be replaced by “raw products” authorized in organic farming such as crushed limestone, chalk, dolomite,
calcareous algae,
ash or even phosphated, ferruginous, potassic, or clayey limestones (marls) which allow to compensate for other deficiencies. All these products are sold in garden centers or DIY stores.
Also readWood ash: a very effective fertilizer for beautiful vegetables!
What roles can lime play in the garden?
1- Reduce soil acidity
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Acidic soil with a pH below 6.5 has very little microbial life and therefore has difficulty transforming organic waste into mineral material useful to the plant. The calcium ion amendment has the effect of:
To reduce the toxicity of aluminum in sandy or granite soils, thus stimulating microbial life and promoting root development. Its contribution (100 g for 20 kg) can also
activate composting
whose temperature does not rise;
To lighten heavy soils
by giving it a lumpy structure which ensures better water penetration and better fertility;
To
raise the pH.
A value
between 6 and 7.5, favorable for most plants, allows for better yields and often increased resistance to parasites.
2- Reduce lawn moss
A very acidic pH leads to the presence of moss in the lawn or turf but this can also result from excess shade or soggy soil:
Measure the pH with pH paper and distilled water to check the cause;
Prefer to add limestone twice a year to maintain a good soil balance (2 times 150 g/m² spaced 6 months apart instead of 300 g/m²);
Wait at least two months to fertilize the lawn otherwise the effects will be reversed.
3- Protect fruit trees against insects and parasitic fungi
Arboreal lime milk made from powdered quicklime destroys fungi. Copyright (c) 2020 AnkaFed/Shutterstock. No use without permission.
Arboreal lime milk made from powdered quicklime destroys fungi and insect larvae nesting in the rough edges of the bark of fruit trees. Provide protection and a metal container filled with water and
fitted with a lid
to carry out the dilution which causes intense bubbling. Leave for several hours before stirring and applying to the trunks. Arboreal White is a ready-to-use solution.
The whitewash is applied before winter, with a large brush, from the base of the trunk to the carpenters after having brushed the bark. Its use is prohibited in organic farming because its action also destroys auxiliary insects!
Kaolin (clay) wash
is an interesting alternative.
How and when to lime a floor?
Appropriate clothing is mandatory
to avoid any risk of burns: gloves, glasses, long sleeves, boots, etc. Quicklime can be added every 3 to 5 years, in autumn and/or in February-March, at a rate of 50 to 200 g/m² depending on the acidity measured in the soil and the type of soil (sandy, clayey, etc.). However, fractionated intakes are more effective and cause fewer harmful effects such as leaching or blocking of certain trace elements. Lime should be banned in already limestone soil!
Lime acts very quickly by activating the decomposition of humus but also strongly disturbs the soil. It thus leads to its depletion if you do not
add nitrogenous organic matter the following year
. As the saying goes, “Lime makes the father rich and ruins the children”!