C - Composition of wood fire ashes
Analysis of the ashes reveals the existence of mineral or metallic substances drawn from the soil by the plant.
When combined, these substances only appear in small quantities. These are mainly:
- sulfur, phosphorus, chlorine, silicon, potassium, calcium, magnesium, iron, sodium.
Others are found in wood only exceptionally such as aluminum, zinc, boron ...
1 - We note first of all a variation of mineral matter with the species. Thus we find more chlorine in conifers than in hardwoods (7 times more in spruce than in oak).
We will find twice as much phosphoric acid in aspen as in oak, and twice as much magnesia in elm as in Scots pine.
Comparisons obviously bear on wood grown in the same geographical conditions.
We can consider that the non-organic elements that constitute the ashes are mostly basic ph with 48% lime, 13% potassium hydroxide and sodium hydroxide and 9% oxides such as: magnesia, iron oxide, manganese oxide.
Acid constituents: phosphoric acid, silicic acid, sulfuric acid are less present in the ash.
Ashes can therefore be used to increase the pH of an overly acidic soil.
2 - The nature of the soil has a considerable influence on the chemical composition of the ashes. The tree draws from the soil the elements that suit it in a proportion all the stronger as they are more abundant. Thus in a silico-limestone soil the chestnut will absorb 15% less limestone than if it is planted in a chalky soil.
3 - The nature and quantity of the mineral matter forming the ash also varies with the various parts of the tree. The bark contains more than the wood, the branches more than the trunk and the trunk more than the roots. Silica and lime are more abundant in the bark than in wood while potash dominates in wood.
4 - There was also a variation depending on the slaughter season. If you slaughter in summer, you find a higher proportion of potash and phosphoric acid. These elements favoring certain fermentation organisms, the conservation of such wood will be less good.
5 - Where are the mineral elements preferably located? In some cases these elements normally permeate the walls of the cells with their solutions.
Sometimes they also form crystals visible under the microscope, in the cell cavity. These crystals of lime oxalate, of silica lime carbonate sometimes appear even with the naked eye.
6 - The properties of woody material can be quite strongly influenced by the presence of mineral matter. Phosphoric acid and potash, in the presence of water, and at a suitable temperature, are first-rate foods for molds.
Some elderly people can still remember the time when we did the laundry with the wood ash, using the natural potash they contain and, in the Middle Ages, we introduced the soda necessary for making glass by means beech ash or some particularly rich herbs from this product.
According https://www.econologie.com/composition-e ... -3465.html