Wood fibers are a promising basis for completely peat-free potting soil or can be used as an aggregate for the peat portion to reduce. We will introduce you to the production, properties, use and sustainability of wood fiber soils.
Peat-free soil such as wood fiber potting soil has become an important symbol of responsibility towards our environment. This creates a high pressure to change on horticultural companies, but also the opportunity to recognize the new customer demands as a purchase argument.
However, while hobby gardeners and service horticulture find it easy to switch to peat-free substrates such as wood fiber soils Production nurseries rely on homogeneous and "as usual" controllable substrates, because these form the basis for a (financially) secure and plannable operational sequence. A switch to wood fiber substrate is therefore associated with greater risks. It is all the more important to be well informed before switching to peat-free or peat-reduced soils.
"Contents"
- Wood fiber: peat substitute with extensive experience
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Wood fiber substrate: manufacture and properties
- Manufacture of wood fiber from wood residues
- Properties of wood fiber
- Use wood fiber substrate
- Can wood fiber substrate replace peat?
- Why is wood fiber substrate sustainable?
- Recommended sources of supply for wood fiber soil
- Contact experts: more information and sources of supply
Tip: Soils without peat did not only emerge with an increasing understanding of the role of bogs. Even before peat was “discovered” as a growing medium, peat-free mixtures were known, in which plants could be cultivated without being tied to the ground.
Wood fiber: peat substitute with extensive experience
The use of wood fiber substrates has been experiencing a clear upward trend for over three decades. The native fiber is increasingly mixed into peat substrates, is the basis for peat-free soils or is even used as the sole substrate in hydroponics.
In addition to the chemical and physical properties that are beneficial for plant growth, the sustainability of the product is of course an advantage of the softwood fiber used. With increasing environmental education (especially among the younger generations), the argument of sustainability becomes a strong selling point. This gives wood fiber potting soils the chance to become part of the unique selling points of sustainable and future-oriented companies.
By the way: In addition to the wood fiber substrates that are already widely used today, compost soils are also a popular alternative to peat, which hobby gardeners especially like to use. They are comparatively heavy and their qualities are absolutely satisfactory even for more demanding private gardeners. However, they are not biochemically stable. During transport or cultivation - despite the use of quality-assured RAL composts - there may be strong deviations in the compost properties. For example, you can change water and air capacity and nutrient availability. Due to this instability of the properties, compost-based substrates for commercial cultivation are not yet practicable.
Wood fiber substrate: manufacture and properties
Wood fiber as a substrate component has been examined by various horticultural institutes and can also be observed in its practical application. Weihenstephan-Triesdorf University of Applied Sciences and Industrieverband Garten e. V. as well as several state research institutes have compiled extensive information on wood fiber as a substrate component.
Manufacture of wood fiber from wood residues
Chemically untreated softwood is used to produce wood fibers. Many hardwoods contain too many disruptive phytochemicals, such as tannins (tannins) and phenols, which can hinder plant growth. Softwood, which is left over from the woodworking industry, is used as the starting material - for example, wood chips, saw or planed fractions can be used. Thermophysical digestion or the steam explosion process can be used to extract the loose fibers from the compact cell structures of the plant-based wood body. In both processes, bothersome resins and tannins are largely broken down. Subsequently, the pH value, wettability, decomposability and color are optimized in further treatments in order to facilitate or beautify the use. The color in particular has a great influence on private customers, because they expect a dark color from potting soil.
Due to its large C / N ratio, wood fiber has the negative property of immobilizing nitrogen when it is microbially degraded. In order to prevent the associated nitrogen deficiency in the cultivated plant in the substrate, the fibers are treated with slowly released nitrogen. This "impregnation" can also be done with organic nitrogen fertilizers.
Properties of wood fiber
The properties of wood fiber are relatively close to those of peat, but the water capacity is clearly different. Although the pore volume is very similar to that of peat, the high proportion of coarse pores results in a significantly higher air and significantly lower water capacity. The resulting loose structure effectively prevents plant roots from experiencing water stress due to the exclusion of air. Unfortunately, as with any organic substrate, the loose structure is not permanently retained, but is reduced over time by sagging. The decomposability of wood fibers is very pronounced, but the structural stability can be achieved through suitable Manufacturing process improved or ignored in the case of short cultivation times of up to five months will.
Thanks to the thermal digestion process, wood fiber is basically free from weeds and pathogens. The pH value of 4.7 to 6.0 is in a very favorable range for most cultivated plants and is good downwards, but hardly buffered upwards. In addition, wood fiber is basically low in salt and contains hardly any soluble nutrients - apart from potassium, which, at up to 100 mg per liter of wood fiber, can be five times as high as in peat.
By the way: The quality of the substrate raw materials should be checked to ensure the homogeneity of the wood fiber soils. The raw materials can be certified with the RAL quality mark.
Use wood fiber substrate
The physical properties of wood fiber and wood fiber substrates enable it to be used, for example, in perennial cultivation outdoors and in container cultivation of woody plants. Wood fiber can also be used for closed cultivation methods (damming, mat, channel irrigation, sack cultivation) They are used, especially because the high drainage capacity leads to waterlogging and thus also many root diseases prevent. Instead, the good air flow promotes healthy root growth.
On the one hand, wood fiber is easy to wet, on the other hand, the surface dries quickly, which prevents weed and moss growth - including liverwort. Even if it is only added to peat substrates, wood fiber improves the wettability.
In cultivation it must be noted that wood fiber soil requires a shorter watering interval than peat substrate due to its lower water capacity. However, experiments have shown that in substrates with wood fiber the loss due to transpiration is less than in pure peat substrates.
Because of the one-sided buffered pH value, caution is advised, especially with lime-rich irrigation water, in order not to reduce the availability of some micro-nutrients, such as iron.
When fertilizing substrates based on wood fiber, it should be noted that the fiber itself hardly contains any nutrients, which means that the basic fertilization must contain all the essential nutrients. Wood fiber itself only has a minimal ion exchange capacity, which is why suitable mixing partners are essential in order to avoid excessive salt concentrations at the plant roots. Clay, but also quality-assured compost in small quantities, has proven to be a suitable mixing partner in this context.
| Properties of untreated wood fiber | |
| Bulk density (g TS / l) | 60 – 130 |
| pH (CaCl2) | 4,7 – 6,0 |
| Soluble salts (g / l) | 0,03 – 0,2 |
| Soluble nutrients | 50 - 100 mg K2O / l |
| N-immobilization | Strong |
| Decomposability | Strong |
| Pore volume | 92 – 96 |
| Air capacity (vol .-%) | 45 – 65 |
| Weed and pathogen population | Very little |
| Wettability | Hydrophilic |
(based on: Weihenstephan State Research Institute for Horticulture, Series: Substrate Components, Part 6, April 2008 edition)
Can wood fiber substrate replace peat?
Wood fiber soils made from high-quality fibers and supplemented with coordinated mixture components can definitely replace peat and help to produce plants of high quality. This is especially true in gardening and landscaping as well as for private gardeners.
In professional production horticulture, the conversion of the crop management, the adaptation of the Logistics and marketing requirements for future-oriented investments in Wood fiber earths.
Watering intervals and fertilization changes; for long-term crops, additional repotting may even have to be planned. The exchange of experiences with similar horticultural companies and substrate manufacturers helps, especially if no literature has yet been published for one's own culture. Taspo, colleges and universities with horticultural institutes as well as the state research institutes and Chambers of Agriculture are valuable sources of information that have already attempted to various crops be able to show. Particularly valuable are the results of the TeiGa project, which were published freely available, and the growth various ornamental, vegetable and nursery plants in peat-free, peat-reduced and classic peat substrates together to compare.
In addition, before switching to wood fiber substrate, it must be ensured that its suppliers are able to deliver in the long term and with consistent quality. This usually also includes a suitable marketing strategy to make customers aware of the new quality of the product.
By the way: It cannot be ruled out that with adapted cultivation even plants of significantly higher quality can be produced. The Austrian herb and vegetable grower Erwin Seidemann reports, thanks to his completely peat-free mixture to obtain more durable, vigorous and pathogen-free plants, for which he received positive feedback from customers harvest.
Why is wood fiber substrate sustainable?
In an experiment by the Zurich University of Applied Sciences (ZHAW), the ecological balance of various peat substitute products was compared with peat. The following parameters were considered over the entire life cycle of the substrate components:
- Contribution to the greenhouse effect
- Total environmental impact
- Cumulative energy expenditure
- Freshwater eutrophication
- Land use
The life cycle assessment works with a standardized point system that, in addition to the CO2-Emissions also include other environmental impacts. Compared to peat, wood fiber scores with just a tenth of the greenhouse gas emissions and the fact that waste is recycled and renewable raw materials are used in production.
The Swiss research office Quantis has also carried out a life cycle analysis of peat and other substrate raw materials, but with different parameters:
- Contribution to the greenhouse effect
- Scarcity of resources
- Human health
- Ecosystem effect
Here, too, wood fiber scored points with a comparatively very low impact on ecosystem quality, human health and the greenhouse effect.
Both studies show that wood fibers and wood chips compared with alternatives lowest greenhouse gas emissions, lowest environmental impact and lowest energy consumption cause. In addition, wood fiber substrate scores well in terms of future availability and potential social risks. Human health and the quality of the ecosystems in which wood fiber grows are also protected.
It should be noted that wood fiber as a substrate component competes with its use as an energy carrier, so that availability and thus price depend on it. It is therefore important to turn to reliable suppliers when purchasing wood fiber substrates.
Tip: The social risks were considered in the above study because of some alternatives due to pollution drinking water or the high consumption of resources affect the local population of the extraction site can.
| Substrate component | Contribution to the greenhouse effect (in kg CO2 equivalents per m3) |
| Black peat | 308,0 |
| compost | 277,0 |
| Wood fiber | 64,0 |
| bark | 105,0 |
| Coconut pulp | 69,5 |
(based on: Quantis Switzerland, Final report for EPAGMA (2012), Comparative life cycle assessment of horticultural growing media based on peat and other growing media constituents, p. 110 – 112)
Recommended sources of supply for wood fiber soil
Neither in the hobby area nor in earths for professional use is there a cross-brand seal of approval or quality that indicates the good Functionality or can read the homogeneity across production batches. Each company finds the best source for wood fiber earths individually through exchanges with other companies and substrate manufacturers as well as through their own tests.
The RAL seal of approval, which is otherwise highly recommended, checks that it is weed-free and that the content is more soluble Nutrients (in relation to the declared values), the bulk density, the nitrogen immobilization and other things more. However, it does not make any statement as to whether the substrate is good or bad for plant cultivation.
Contact experts: more information and sources of supply
Are you interested in wood fiber or would you like further information and expert recommendations on sources of supply? Send us an inquiry with your contact details and a Plantura expert will contact you as soon as possible. We're here to help!
