COMMON Reed

Note: unless stated otherwise the data on this webpage are taken from the Dutch research report "Marktverkenning Paludicultuur Kansen voor de landbouw in veenweidegebieden met behoud van veen". 2016

Description

Reed (Phragmites australis) belongs to the grass family and is a perennial wetland plant distributed all over the world. It consists of rhizomes and robust leafy stems with dropping linear leaves and can reach up to 3 metres. Growing in brackish or freshwater at or above ground level, reed often occurs on riverbanks, the shores of gulfs or lakes, and on nutrient-rich peatlands. Reed is a versatile plant with many different applications such as an industrial material, energy production, agricultural uses and water treatment.

establishment & maintenance

In summer (June – August) seedlings should be planted at a density of 0.25 – 4 plants per m2 after tilling the soil (Geurts & Fritz, 2018; Närmann et al., 2021). The seedlings can be raised in greenhouses with a high success rate (80% germination rate) if high quality seeds from a comparable donor site are used. Direct sowing can be done in spring, but care must be taken to keep the water table low and constant until the plants have reached sufficient size (Geurts & Fritz, 2018). For planting, and during the first two years, the water table should be kept slightly below ground at about -0.5 meters. This relatively low water table allows for machinery to access the field in this starting period, making the use of planting machines possible. After two years the water table can be raised up to 2 meters to maximize water retention, but ideal growth rates are achieved at a water table of 40 cm (Närmann et al., 2021). Reed grows best in nutrient rich circumstances, with a high nitrogen availability. This makes paludiculture with reed perfect for degraded soils that have been used for intensive agriculture.

Harvesting & Yields

After 2 – 3 years the reed can be harvested, the harvest time depends on the use. Reed for thermal utilisation should be harvested in late winter since the content of combustion critical substances is lowest during that period. For thatch, reed should be harvested between January and March after the first frost to maximize dryness of the biomass (Wichtmann et al., 2016). Harvesting is ideally done when the wetland is frozen to allow for easier access, although adopted machinery may be used in areas where the ground does not freeze (Köbbing et al., 2013). Summer mowing can also be done to increase specific biodiversity, but this will restrict growth in subsequent growing seasons.

Harvest in winter can yield 4.6 – 15 t DM ha -1 per year, whereas summer harvest can yield 6.5 – 23.8 t DM ha -1 per year. Especially if nutrient input is limited, yearly winter harvest can eventually lead to lower yields. Since rewetted peatlands often have high nutrients loads, reed yield is expected to be stable for the first few years, after that period a less nutrient demanding crop such as sedges can take its place (Närmann et al., 2021).

ecosystem services

Paludiculture with reed strongly reduces carbon-dioxide emissions, while increasing methane emissions. This results in emissions of about 0-7 t CO2e per hectare depending on the height of the water table, with higher water tables leading to lower emissions (Närmann et al., 2021; Tanneberger et al., 2022). Compared to traditional drainage-based agriculture, this is a huge reduction in GHG emissions, especially if the farmyard and livestock emissions from traditional agriculture are considered (Liu et al., 2023). This GHG emission reduction allows for an additional income pathway by selling carbon credits.

If part of the reed plot is mowed in winter, this can have a positive effect on multiple songbird species. Early summer harvesting has, in most cases, a negative effect on bird biodiversity and should therefore be avoided. Late summer harvesting can promote some specific threatened bird species but is not compatible with agricultural production targets. Rotational cutting of the reed beds, creating different succession stages, is most likely the best option for both bird and arthropod biodiversity. The same has been found for plant biodiversity, as some plants benefit from regular mowing, and other plants benefit from a lack of disturbance (Wichtmann et al., 2016). This rotational cutting leaves some parts of the reed beds untouched for multiple years, allowing for reed to not only preserve the existing peat layer, but also build up new peat (Närmann et al., 2021).

applications

In Europe, reed is used mainly as a material for building and insulation. Reed can also be used as fuel for heating plants. In Germany and the Netherlands, reed is used for roof thatching. Due to the growing demand for ecological building materials, reed is now mostly imported from other countries (Wichmann & Köbbing 2015). Paludiculture with reed could provide a local source of reed for thatching, reducing the need for import.

In China, reed is regarded as a plant of high medicinal value. The main medicinal parts of reed herb are the roots (Lu Gen) and stems (Wei Jing), which have very similar medicinal properties. Reed is known to have anti-asthmatic, styptic, diuretic, blood-purifying and fever-reducing effect. It is also often used as an emetic, cough medicine and antacids. In China this crop is in the pharmacopoeia. A pharmacopoeia is a book containing statutory regulations for the composition, preparation method and approval of medicines according to certain pharmaceutical standards in order to ensure the uniformity of those medicines. This concerns medicines, plant extracts and oils. In the European Pharmacopoeia and in the American Herbal Pharmacopoeia, Reed is not described.

The crop is on the INCI list CAS number: 84604-02-4. In the cosmetic industry, reed extract is used to make skin conditioning or tonic.

Besides China, reed is not sold in any other country as a raw material for high-quality applications. In The Netherlands various large market parties have been approached but are not interested. The Chinese market is relatively large, but they are self-sufficient. We do not see any opportunities to enter the Chinese market at the moment. At present it seems that the market opportunities for reed in the high-quality applications are poor.