Plant ash
Plant ashes are the components that remain after the incineration of biomass chemically untreated before harvest ( bark , wood chips , sawdust , logs , whole plants , straw , grass , other biogenic residues from agriculture and forestry , garden and green areas or from food production ).
Under no circumstances can the ashes from waste and waste wood incineration plants be described as plant ash.
Ecological importance of plant ashes
Plant ashes from biomass furnaces are valuable secondary raw materials for agriculture and forestry. Due to their nutrient content, the soil-improving effects and in accordance with the ecological principle of closed production cycles, plant ashes can and should be returned to natural cycles to protect the soil and the environment. The return of nutrients has become all the more important in recent years, because on the one hand ever larger quantities of ash are generated and on the other hand the natural resources for fertilizer production are becoming increasingly scarce.
Ash attack
The incineration of biomass produces considerable amounts of plant ash, which should be returned to agriculture and forestry. The values in the following table are always based on the dry substance, i.e. on completely dry material.
| fuel | Ash content [% by weight TS] | [MJ / kg] Hu (TS) |
|---|---|---|
| bark | 5 - 8 | |
| Wood chips from the whole tree harvest | 2 - 3.5 | |
| Wood chips from the cut debris | 5 - 11 | |
| Wood chips with bark | 1 - 2.5 | |
| Wood chips without bark | 0.8 - 1.4 | |
| Shavings | 0.5-1.1 | |
| Wood pellets made from shavings | 0.6 - 2 | |
| Spruce wood (without bark) | 0.4 | 18.0 |
| Beech wood (without bark) | 0.5 | 17.3 |
| Hardwood (without bark) | 0.6 | 16.9 |
| Straw and whole plants | 4 - 10 | |
| Straw clean | 2 - 6 |
Chemical composition of the ashes
The chemical composition of the plant ashes shows that it contains essential valuable components that the following renewable plants would otherwise lack as raw material. These are in particular phosphorus and potassium, as can be seen from the table below.
| Contents in different ashes [% DM] | P 2 O 5 | K 2 O | CaO |
|---|---|---|---|
| Bark ash | 2 - 4 | 5 | 40 |
| Forest woodchip from the top of the whole tree harvest | 5 - 8 | 8-15 | 20 - 35 |
| Wood chip ash | 4th | 7th | 45 |
| Sawdust | 3 | 7th | 35 |
| Straw ash | 3 | 12 | 7th |
| Whole plant ash (straw with fruit) | 12 | 18th | 6th |
Current use of the plant ashes
Due to the current inadequate guidelines, plant ashes can currently only be partially used. An addition to compost is permitted, but the amount that can be used in it is too small to use the plant ashes from biomass heating plants and biomass heating plants .
In Austria, therefore, a guideline is being written which in particular allows the use of plant ash in the forest . Grate ashes from biomass incineration plants would be particularly suitable for the construction of forest roads , but are not used due to the lack of guidelines and the lack of information for the forest owners.
Individual evidence
- ↑ Guideline for the proper use of plant ashes for recycling on areas used for agriculture and forestry ( Memento of the original from February 21, 2016 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. (PDF; 864 kB), Federal Ministry of Agriculture, Forestry, Environment and Water Management, Vienna, 1st edition 2011
- ↑ OBERNBERGER Ingwald, partly own measurements by A. Oberhammer
- ↑ a b c Agrarplus: Characterization of biomass
