More and more often there are opinions about the harm of synthetic fertilizers produced industrially. Among eco-farmers with many years of experience, such arguments are even more common. Of course, it is also impossible to leave the soil without fertilizers at all, so most eco-farmers have recently been trying to switch to using exclusively organic fertilizers.
The most well-known fertilizers of natural origin are, of course, manure and compost. A little less often people hear about such a fertilizer as sapropel. And only a few farmers, in the conditions of civilization and the industrial boom who have not forgotten the experience of their ancestors, know that ash, ordinary wood ash left in the stove or hearth after burning wood or other fuel, can be used as a fertilizer.
But now wood processors produce millions of tons of wood pellets, Euro-firewood from sawdust or burn offcuts and wood processing residues, obtaining valuable products that are simply disposed of in garbage dumps.
Wood ash as a fertilizer contains about 30 substances that are required by agricultural crops as elements of their nutrition.
These are mainly potassium, phosphorus, calcium, iron, magnesium, silicon, sulfur. At the same time, using combustion products as fertilizer, it is necessary to take into account that they practically do not contain such an important element as nitrogen, the compounds of which evaporate during combustion along with smoke.
As a fertilizer, it can be used both in its usual dry state and in the form of solutions. The second option is preferable, since it allows the most complete use of all the useful substances – dissolved in water, they are absorbed by the soil and the root system of plants much faster than this occurs when using dry fertilizer.
To obtain an ash solution, dissolve one glass in 10 liters of water. The resulting solution is used to treat 1 to 2 square meters of a garden or field.
Using dry ash as a fertilizer involves adding it when digging or loosening the soil. Since some of the properties will be lost when added, the concentration should be much higher than when using a solution.
So, it is customary to add 3 to 5 glasses of dry ash per 1 square meter. Clay soil can be fertilized in this way in the spring or fall, but when it gets into sandy soil, it quickly washes out, so sandstone can only be fertilized in the spring, after the rainy season.
Some people use ash as an additive to other organic fertilizers. For example, if you sprinkle ash on each layer of grass and food waste when laying a compost heap, the organic matter will turn into humus at a faster rate. If you decide to use this technology, add 10 kilograms of ash per cubic meter of compost.
It goes without saying that the fertilizing properties of ash are entirely determined by its composition. It, in turn, depends on what material was burned to obtain ash.
For example, when burning thin brushwood or small branches of young trees, the ash contains much more nutrients than the ash obtained as a result of burning large logs from old trees.
And this leads to the following conclusions: in timber processing, branches, tree bark, roots, and slabs remain in the forest and are not processed, causing great harm to nature by acidifying the soil. If we process all these remains into charcoal and ash, we help nature three times, without acidifying the soil and obtaining activated carbon for water purification and ash for fertilizing fields. In Russia, at the moment, the production of granules (pellets) from ash is practically not used, this is a separate market for eco-fertilizers.
The highest content of useful substances in ash is obtained by burning potato tops. In this case, about 30% of the ash volume is potassium, one of the most useful fertilizing elements. Also, such ash contains a large amount of calcium and phosphorus.
Ash enriched with potassium can also be obtained by burning ordinary dry grass, which by the end of summer and early autumn fills almost all wastelands on the outskirts of summer cottages.
Ash obtained as a result of burning wood species such as oak or birch, which are also rich in calcium and phosphorus, is also rich in potassium. In general, the higher the hardness of the wood, the more potassium the ash will contain after its combustion.
If the condition of the soil on your site or field requires enrichment with phosphorus, then to obtain ash you need to burn tree bark or wheat straw. This fuel contains the most phosphorus. As you can see, ash as a fertilizer, especially wood ash, is very useful for improving the condition of the soil.
The article was prepared by Andrey Kichaev, an expert at “Geoburo“, August 24, 2024.