Category: Grasses


Arundo donax L.

General info

Originating from East Asia this water loving perennial plant grows in rich soils in water near lakes, ponds, marshes, rivers and other bodies of water to achieve its maximal biomass yield. Despite originating in East Asia it is now certified as being present in all inhabited continents across the globe suggesting a range of adaptabilities.

A. donax is a sterile plant able to reproduce asexually via its rhizomes which undergo exploratory expansion in the spring and summer or via rhizome fragments or rooting at the nodes. It ranges in height from around 2–9 m and undergoes this growth rapidly due to an unusually saturated photosystem for a C3 plant variety along with a development more associated with a C4 plant. It is one of the biggest herbaceous plants in the world which means it is productive as a bioenergy crop due to quick and large accumulations of biomass achieved.

In regions with warmer winters, it is evergreen but dies back in climates with freezing winter temperatures. However, it does produce biomass with significantly high moisture levels, which can be a complication for cutting, handling, conserving, storing and combustion processes. The moisture is more welcomed for ensiling based bioenergy production such as biogas production.

Cultivation and agronomy

A. donax plantations are said to produce biomass for around 10–15 years or even longer if harvested frequently and fertilised; though later harvest years tend to see a decline in biomass yields achieved. Similar to other rhizome species, it does require considerable soil restoration to reutilise the land for other planting aspects due to the need to ensure all rhizome is removed and destroyed to prevent re-establishment.

A. donax grows well with minimal inputs, though water requirements in the initial year of establishment can be crucial. Despite not needing fertiliser to thrive, productivity is increased when fertiliser is used. Like many other promising bioenergy grass-type crops, it is applicable to marginal lands which reduces competition with food production.

It has been reported to produce on average 30–40 Mg ha-1 dry matter per year with a significant range around this value (20–177 Mg ha-1), largely due to locally warmer climates in USA studies. It has outperformed both M giganteus and switchgrass (Panicum virgatum L.) in multiple studies, with above-ground dry biomass tonne ha-1 yr-1. Due to its large size, it may be a challenge for harvesting processes but it is suggested that slight modifications to machinery used for crops such as sorghum and corn can allow functional harvesting of A. donax.

Due to its halophyte nature, it is applicable to saline soils and can thrive in brackish estuaries. In the first establishing crop year, yields will be lower and more weed control will likely be needed via herbicide treatments. The sterility of this species makes it an interesting and controllable prospect as a bioenergy crops.

In energy production it appears to outperform traditional energy crops for bio-methane production (average 12,618 Nm3 CH4 ha-1) and, provided biomass pre-treatments are utilised, it also appears to outperform more energy crops with regards to bioethanol production (11,000 – 15,000 litre ethanol per ha-1). It delivers comparable direct combustion energies to those of miscanthus, poplar and switchgrass (18.7 MJ kg-1). As it has potential higher yields achievable than these species it is suggested that between 40–60% more energy could be produced per ha­-1 via Arundo. Though, for direct combustion, it has been noted to have problematically high ash content compared to equivalents miscanthus and switchgrass but this could be resolved via timing of harvest, as earlier harvesting can reduce dry matter percentage of ash by more than twofold.

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Relevant research

Corno, L., Pilu, R., & Adani, F. (2014). Arundo donax L.: a non-food crop for bioenergy and bio-compound production. Biotechnology advances, 32(8), 1535-1549.

Amaducci, S., & Perego, A. (2015). Field evaluation of Arundo donax clones for bioenergy production. Industrial Crops and Products, 75, 122-128.

Webster, R. J., Driever, S. M., Kromdijk, J., McGrath, J., Leakey, A. D., Siebke, K., … & Long, S. P. (2016). High C3 photosynthetic capacity and high intrinsic water use efficiency underlies the high productivity of the bioenergy grass Arundo donax. Scientific Reports, 6(1), 1-10.


Miscanthus giganteus
Terravesta ‘Athena’ variety

General info

Miscanthus is a C4 rhizomatous perennial monoecious grass, which produces woody stems and originates natively from the southeast of Asia. It was originally imported into Europe as an ornamental plant largely M. sinensis but the hybrid M. giganteus’s rapid and sizable annual growth makes it an interesting energy crop consideration. The Terravesta commercial Athena variety further shows improved growth rates over the standard M. giganteus levels observed.

Cultivation and agronomy

Miscanthus is suitable to grow on less productive marginal lands and flourishes in most soil types. The sterile hybrid, largely utilised commercially, is produced via asexual rhizome propagation, this makes the crop relatively uniform, helping with maintenance and harvesting.

It can be harvested annually from the second year onwards, producing 4 – 13 tonnes per hectare per year in the second year, up to 10–13 in the third year, with peak harvests of up to 10-14 tonnes per hectare being seen in some studies with commercial varieties.

Stands of miscanthus remain feasible for harvest for between 10 – 25 years. Higher yield values above are associated with commercial strains such as Athena by Terravesta in the UK whilst traditional M. giganteus strains achieve closer to 4 – 8 tonnes per hectare (relative to year of cut etc).

Similar to other rhizome species, it requires considerable soil restoration to reutilise the land for other planting aspects to ensure all rhizome is removed and destroyed to prevent re-establishment.

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Relevant research

Clifton‐Brown, J., Harfouche, A., Casler, M. D., Dylan Jones, H., Macalpine, W. J., Murphy‐Bokern, D., … & Lewandowski, I. (2019).

Breeding progress and preparedness for mass‐scale deployment of perennial lignocellulosic biomass crops switchgrass, miscanthus, willow and poplar. Gcb Bioenergy, 11(1), 118-151.

Reed Canary Grass

Phalaris spp. Phalaris arundinacea

General info

Reed canary grasses are C3 native perennial grass species native to the Europe, Asia and North America. They can propagate via seed or rhizome and grow to maximum heights of 2 m. These grasses enjoy damp habitats and ditches or being beside water sources. They are often considered to be an invasive weed within wetland environments where they inhibit native vegetation and impact natural biodiversity.

They have been utilised as far back as the 1800’s in their inclusion for pasture species seed mixes, with modern breeding and genetic evaluation looking towards optimising their potential as a bioenergy crop via projects such as “Optimisation of Reed Canary Grass as a Native European Energy Crop” (ORNATE).

Cultivation and agronomy

Reed canary grass achieves yields of around 12.5 oven dried tonnes ha-1 y-1, this provides relatively equivalent yields to the C4 grass miscanthus with much lower establishment costs. However, it is more nutrient hungry than miscanthus making it less feasible for environmental energy production depending on their energy utilisation method of choice.

Canary grass species have a wide range of physiological tolerances including to flooding, drought, freezing, and grazing, making them promising for the variety of possible utilisations including marginal land use.

There are several pests known to impact growth of these grasses as well as difficulties surrounding harvesting due to incomplete senescence. They are also known to suffer from lodging issues, which can impact the yield achieved and be undesirable for a bio energy crop, where ease of harvest uniformity is often desired.

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Relevant research

Landström, S., Lomakka, L., & Andersson, S. (1996). Harvest in spring improves yield and quality of reed canary grass as a bioenergy crop. Biomass and bioenergy, 11(4), 333-341.

Jensen, E. F., Casler, M. D., Farrar, K., Finnan, J. M., Lord, R., Palmborg, C., … & Donnison, I. S. (2018). Reed canary grass: from production to end use. Perennial Grasses for Bioenergy and Bioproducts, 153-173.

Switch Grass

Panicum spp – Panicum virgatum

General info

Switchgrasses are C4 perennial monoecious grasses native to North America with over 400 species within the genus. They are propagated by seeds and grow up to around 2.7 M in height. Similar to reed canary grass, switchgrass can also be incorporated into forage considerations for grazing (suitable for cattle only due to toxicities in other animals) and straw produced can be used for livestock bedding.

Attempts are being made to achieve domestication and commercial varieties of switchgrass via targeted breeding to enhance bio-energy quality varieties. Currently Transgenic approaches lead on this, with switchgrasses susceptible to transformation via agrobacterium, though overall this method of change is more costly than traditional breeding.

Cultivation and agronomy

Switchgrass has shown suggested yields of around 14 oven dried tonnes ha-1 y-1 with certain studies predicting yields up to 20 dried tonnes ha-1 y-1 in modelling scenarios rather than practical applications. It remains harvestable for 10–12 years before replanting considerations are needed. It is harvested annually using similar machinery to that commonly used for pasture activities.

The species has an extremely widespread distribution across Northern America due to its adaptable nature with multiple ecotypes being present. The two main ecotypes/cytotypes of interest, for their roles in incorporation into UK growth strategies and inclusion as bioenergy crops, are the upland and lowland ecotypes. The upland ecotypes are generally shorter and more cold-tolerant potentially having more applicability in the UK. However, the lowland ecotypes can achieve higher yields in the right environments, despite being more sensitive to stresses like moisture than their upland equivalents.

An important consideration with switchgrass species in the UK, is their apparent lower responsiveness to N fertilizer, yield increases seen on application of N were around half of those seen with similar bioenergy crop reed canary grass. As such, N fertilisation and environmental balances associated with these grass species, may need careful consideration in any bioenergy production strategy.

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Relevant research

Smeets, E. M., Lewandowski, I. M., & Faaij, A. P. (2009). The economical and environmental performance of miscanthus and switchgrass production and supply chains in a European setting. Renewable and sustainable energy reviews, 13(6-7), 1230-1245.

Allison, G. G., Morris, C., Lister, S. J., Barraclough, T., Yates, N., Shield, I., & Donnison, I. S. (2012). Effect of nitrogen fertiliser application on cell wall composition in switchgrass and reed canary grass. Biomass and Bioenergy, 40, 19-26.

Clifton‐Brown, J., Harfouche, A., Casler, M. D., Dylan Jones, H., Macalpine, W. J., Murphy‐Bokern, D., … & Lewandowski, I. (2019). Breeding progress and preparedness for mass‐scale deployment of perennial lignocellulosic biomass crops switchgrass, miscanthus, willow and poplar. Gcb Bioenergy, 11(1), 118-151.