Cattail
(Typha SP.)
Description
Typha is a genus of tall reedy marsh plants (family Typhaceae). There are three species of the bulrush/cattail family native to Central Europe: Lesser Cattail/Bulrush (Typha angustifolia), Common Cattail/Bulrush (Typha latifolia) and their hybrid (Typha x glauca), all of which are highly productive and robust plants. These perennials consist of a strong, starchy rhizome and stiff upwards growing tapered leaves, which can reach between 1.5 and 3 metres. The leaves contain a distinct system of air chambers, which make them interesting as insulation material. Typha plants grow in water levels of 0-40 cm and naturally occur in fresh or slightly brackish waters. Therefore, degraded and rewetted fens with high nutrient availability are ideal locations for cultivating cattail and irrigation with nutrient-rich/polluted surface water is possible or even recommended. Cattail carries its unisexual flowers on cylindrical spikes, with the male flowers withering and falling off after pollen has been released, so that the characteristic brown fruiting spikes remain. When reaching maturity, the spikes disintegrate into cotton like fluff of wind-dispersed seeds.
establishment & maintenance
Cattail can be established via planting or sowing. Planting is fast and successful, but also more expensive. To gain complete cover, 1-2 plants per m2 need to be planted. The cattail will then colonize the rest of the plot vegetatively. Sowing should ideally be done between Mai and July and requires wet or inundated soil. The seeds can be germinated beforehand to increase success rate, gaps that remain can be filled up with seedlings (Wichtmann et al., 2016; Geurts & Fritz, 2018).
The water table should be between 0 – 40 cm above the surface and height differences in the surface should not exceed 20 cm. This means that equalisation of the soil is required before planting or sowing. Cattail grows best with high nutrient content in the soil and/or incoming water. This provides an opportunity to get rid of nutrient legacies as a result of conventional drainage-based farming. It also allows for the purification of nutrient polluted surface water (Geurts & Fritz, 2018; Närmann et al., 2021).
The water table should be easily regulated. It needs to be slightly below the surface for planting or slightly above the surface for sowing. Once the lants starts to grow the water table should increase to 20-40 cm above the surface. Finally, for harvesting, the water table should be decreased again to allow easier access (Geurts & Fritz, 2018; Närmann et al., 2021).
Harvesting & yields
The first harvest can be done one year after planting or sowing, with a full yield after 2 – 3 years. Harvest times depend on usage of the biomass yield. For use as building material such as blow-in insulation and plates, biomass should be harvested in autumn or winter when the ground is frozen. This also allows for easier access with harvesting machinery. If biomass will be used for animal fodder or energy generation, earlier harvesting in summer is required (Wichtmann et al., 2016). In this case a second, smaller harvest in winter is possible allowing for two harvest per year (Närmann et al., 2021).
For some uses whole plants are needed, while for other uses plants can be shredded. Since the harvesting technique is very similar to that of reed, the same adapted machinery can be used, although more specialized adaptations are still needed (Närmann et al., 2021).
Cattail is a fast biomass producer. Under optimal conditions with regards to hydrology and nutrient availability, cattail yields have exceeded 15 tons of dry matter per hectare and reached yields of 20 to 30 tonnes of dry matter per hectare (C. Fritz, Radboud University Nijmegen; personal communication).
ecosystem services
Like reed, cattail paludiculture greatly reduces carbon dioxide emission but increases methane emission. For cattail this results in emissions of about 6-7 t CO2e per hectare depending on the height of the water table, with higher water tables leading to lower emissions. The bandwidth of water table height is smaller than with reed however, since cattail only tolerates a maximum water table of 40 cm (Närmann et al., 2021; Tanneberger et al., 2022).
The establishment and periodic mowing of cattail fields allows for the recovery of fen specific biodiversity. Characteristic fen plant species have returned in cattail paludiculture fields (Tanneberger et al., 2022). Cattail fields also provide breeding habitat for multiple rare bird species as well as habitat for dragonflies, frogs, and snakes (Graf, 2014). The mowing regime needs to be adjusted to biodiversity goals however, and the cattail field should not be mowed in its entirety all at once to allow for refuges for birds and other fauna (Wichtmann et al., 2016).
Since cattail is very efficient at taking up nutrients from the surface water in which it stands, it can be used for water purification purposes. Cattail fields can for example be established around wet nature reserves to provide a filter for nutrients from the surrounding agricultural fields. The natural resistance of cattail to many herbicides makes it ideal for this use (Theuerkorn, 2014). Although the high nutrient input will promote biomass production, this biomass is likely polluted with herbicides and therefore not suitable for many products (i.e. fodder, building material). This value loss can be compensated by monetizing the water purification services of cattail paludiculture (Närmann et al., 2021).
Applications
The most obvious application for cattail is serving as construction material. This is elaborated below. The table below provides an overview of the applications, including a brief motivation for this choice based on the feasibility period.
Cattail silage as feed can be considered a novelty, which is why due to the naturally limited experience in feeding it to livestock farmers might be cautious about introducing it on their farms. Therefore, it needs trials like the one described above, to gain insights that can be shared with farmers. Another barrier for introducing cattail on farms is the necessity to change machinery, which means financial investment, and get used to different kinds of crop management as well as hydrological infrastructures maintaining the correct water levels for CO2 emissions to be decreasing. Again, farmers will require scientific information and monitoring options.
Cattail pollen production will at the same time be new for farmers and potentially require investment in machinery or hydrological infrastructure, which is why they might hesitate to introduce it on their farms.
Construction & INsulation
Cattail is very suitable for use as an insulation material. Cattail is one of the few plants that consists of a long tear-resistant fibre and a sponge fibre. About 85% of the plant mass consists of the spongy material. This structure and the natural oils make cattail an optimal raw material for lightweight construction elements. The high percentage of polyphenols in cattail protects the building / insulation material against fungi and insects, but also protects the crop during cultivation. Cattail insulation material therefore requires little or no additives and does not emit toxic VOCs (volatile organic compounds). Cattail also has an intrinsic fire resistance, has a heat and sound insulating effect and a buffering effect on moisture and temperature. In contrast to other synthetic or mineral insulation materials, which are harmful to health, the suitability of cattail is high.
In the video below, Peter van der Maas from van Hall Larenstein University of Applied Sciences, explains how cattail can be used as insulation material and the associated value chain.
https://www.youtube.com/watch?v=2C6GXygW5cY&ab_channel=CANAPEProject
The thermal conductivity coefficient is a frequently used criterion for insulation material. Each material has its own thermal conductivity coefficient. The lower this value, the better the material insulates and the thinner the required insulation layer. Cattail has a thermal conductivity coefficient of λ = 0.032 W / m.K. This is comparable to other organic insulation materials. The coefficient of thermal conductivity of small cattail is slightly larger and is 0.0438 - 0.0606 W / m.K (v). Hemp has a thermal conductivity coefficient of 0.040 W / m.K, flax 0.038 and sheep wool 0.035. Cattail insulates just as well as traditional insulation materials, such as mineral wool (0.030-0.050 W / m.K) and EPS (0.032-0.040 W / m.K). Compared to expensive insulation such as vacuum insulation (λ = 0.007 W / m.K), however, cattail performs less well. In addition, commonly used synthetic materials such as EPS have disadvantages with regard to fire safety, toxicity and renewable energy. The use of cattail insulation, on the other hand, leads to carbon sequestration in contrast to mineral and synthetic insulation materials, where up to 1 ton of CO2 per m3 is emitted in the production process alone.
In addition to blow-in insulation ("loose" insulation material), small cattail is also extremely suitable for construction panels with a high insulation capacity, which is comparable with OSB panels in terms of strength and insulation value, due to its strength. Current buyers / producers such as Typhatechnik and Naporo can process both cattail types.
Bio-Energy
The energy value of cattail is 19.2 MJ per kilogram of plant material vi. By comparison, wood chips have energy values of 17 MJ per kilogram of plant material. The pelletized cattail also has the advantage of not requiring binding agents. Cattail as a bioenergy source is used in Canada (Libau-Marsh region) and locally in Eastern Europe vii. Alternative crops such as Miscanthus and / or hemp are a possible competitor here, but various studies indicate that these - on their own - are not profitable for the bioenergy application ("Teelt van Biomassa niet rendabel"; Bioakkerbouw (in Dutch).
Livestock & Pest control
Livestock Feed and Litter
Using cattail as cattle feed is an opportunity for farmers looking for applications of cattail from rewetted peatlands that either keep livestock themselves or can sell silage to farmers nearby, so that the costs for transportation are not too high. As distribution channels do theoretically not differ from other silage feeds, implementation should be low-threshold considering the selling of produce.
Cattail species are suitable for livestock feed. A Brazilian study x found that Typha domingensis contains 11.5 percent crude protein, digestible fiber 83.1 percent. However, the use of cattail as a primary application is not very obvious, as it cannot compete well against subsidized roughage. It is advisable to use any residual flows for animal feed and litter in potted stables to close cycles. The quality of cattail as animal feed is being investigated in feed experiments within the 'Peat, feed and beyond' project at the VIC / KTC experimental farm by the Louis Bolk Institute and Radboud University Nijmegen. Our own analyzes have shown that the samples contain carbohydrates (glucose, sucrose), amino acids (phenylalanine in stem and flower; alanine & tryptophan in rhizome), choline, phosphatidylcholine, N-aromatic compound (adenine), fatty acids and phytosterols. Some of these substances are health-promoting substances and for that reason could be added to animal feed. In order to determine whether any residual flows of cattail can be used definitively in the animal feed industry, the calorific value of the residual material must be calculated. At the moment it is not yet clear when the crop will be harvested and whether the resulting residual material can actually be a supplement for roughage. Only qualitative analysis has been performed, no quantitative analysis (seasonal variation of substances including their level may occur).
Cattail pollen as feed for predatory mites
Using cattail pollen as feed for predatory mites used as biological pest control in greenhouses is an opportunity for farmers looking for applications of cattail from rewetted peatlands that have no use of the plant on their own farms. As cattail pollen is a niche product, distribution channels will possibly differ significantly from established ones. Farmers thus require information on possible buyers and the design of value chains.
OTher applications
Cattail plant material is used in traditional Chinese medicine as a blood coagulant and against bloody stools (wound healing). The pollen of different varieties of cattail is extracted for this. Cattail can be used for bioremediation. This means that cattail can be used to mine phosphate and nitrogen from surface water and sediment xii. Cattail can discharge 500 kilograms of nitrogen per hectare per year and remove 30-50 kilograms of phosphate. When used as biofuel, these minerals can be recovered after incineration. In addition, the pollen of cattail contain phytosterols. These are health-promoting substances, which are marketed as 'functional food' because of the beneficial effects on cholesterol absorption in the intestine (Grosshans, 2014). In addition, phytosterols also appear to be used for bees and as a plant hormone, which is responsible for the majority of the growth and flowering of the plant.
In the past, the roots of cattail were used. The roots contain starch. In view of the unknown market opportunities as well as the likely negative ecosystem impact, this has not been investigated in this study. The seeds of cattail make up about 20% of the total dry mass. That comes roughly equivalent to 1.5 tons of seed on an entire hectare. These parachute seeds can be used in reinforcement of (clay) mortar, which is used for bricklaying, tiling, plastering, joints and so on. These seeds contain oil (approx. 18%). Technique to harvest the seeds separately from the vegetative parts still needs to be further developed, as the seeds fall out easily. The technique used with hemp oil may also apply to this harvest. The appendix contains a detailed elaboration of the high-quality market opportunities of cattail.
Testimonies of farmers
Restoring peatlands: demonstration of a cattail harvest
A group of farmers interested in sustainable farming methods are participating in a cattail harvest on an experimental plot in the North Bradant province in the Netherlands. The meeting is an opportunity to discuss new economic models of malaria cultivation, their potential and market opportunities.
Aldert van Weeren is the first cattail farmer from North West Europe. He gave us his testimony on reeds and typha business models during the 21 December 2021 webinar "Sustainable Farming for Peatland" organised by Carbon Connects project.
Restoring peatlands: testimony on on-farm composting from reeds and other crops from re-flooded land.
A Belgian farmer testifies on the experimentation of paludiculture, and its valorisation into compost from the agricultural biomass obtained on his flooded plots. A promising economic model.