Elephant grass – a biofuel that improves soil says Earlham Institute

Miscanthus, commonly known as elephant grass, is a promising biofuel thanks to its high biomass yield and low input requirements, which means it can adapt to a wide range of climate zones and land types.

Very little is known about its productivity in flooded and moisture-saturated soil conditions, so researchers at the Earlham Institute in Norwich investigated differences in water-stress tolerance among Miscanthus species to guide genomics-assisted crop breeding.

Higher biomass in flooded conditions

Although researchers observed a significant biomass loss under drought conditions in all of the four Miscanthus species studied, in flooded conditions biomass yield was as good as or better than controlled conditions in all species.

The low number of differentially expressed genes, and higher biomass yield in flooded conditions, supported the use of Miscanthus in flood-prone marginal land.

Dr Jose De Vega, Group Leader at the Earlham Institute, says: “Miscanthus is a commercial crop due to its high biomass productivity, resilience, and ability to continue photosynthesis during the winter months. These qualities make it a particularly good candidate for growth on marginal land in the UK, where yields might otherwise be limited by scorching summers and wet winters.”

It is seen as a viable commercial option for farmers. A previous, decade-long trial in Europe showed that Miscanthus produced up to 40 tonnes of dry matter per hectare each year. This was reached after just two years of establishment, proving its biofuel capacity was more efficient in ethanol production per hectare than switchgrass and corn.

Use marginal land for biofuel

“The global challenge of feeding the ever-increasing world population is exacerbated when food crops are being used as feedstock for green energy production,” said Dr De Vega.

“Successful plant breeding for ethanol and chemical production requires the ability to grow on marginal lands alongside prioritising the attributes; non-food related, perennial, high biomass yield, low chemical and mechanical input, enhanced water-use efficiency and high carbon storage capacity.

“Miscanthus fulfils these for enhanced breeding – saving money and space for farmers, and lending a hand to our over polluted environment by emitting CO2.

“The research team is in the early selection process of high biomass genotypes from large Miscanthus populations that are better adapted to the UK conditions and require low inputs.

The use of genomic approaches is allowing us to better understand the traits that make some Miscanthus species a commercially sustainable alternative for marginal lands and applying this to agri-practices.”

Profitable option that improves soil health

Miscanthus specialist Terravesta has a long-term contract to supply the Snetterton renewable energy plant with 25,000 whole bales. It works with about 300 miscanthus growers, and says the crop could be a profitable option for land unlikely to suit mainstream crops. It can stabilise land, help improve soil organic matter and encourage earthworms.

The roots go down 1-1.5m, and offer benefits in soil improvement on light sandy loam soils.
The paper ‘Physiological and transcriptional response to drought stress among bioenergy grass Miscanthus species’ is published in Biotechnology for Biofuels.

Biomass crops, such as miscanthus, are also one of four cropping options currently under study by Niab as part of the Centre for High Carbon Capture Cropping (CHCx3). Niab’s research focuses on enhancing carbon capture and sequestration in crops and soil-based products, aiming for a net-zero objective. Niab will be holding a seminar dedicated to biomass crops sometime in the spring.

You can read more about novel crops and rotations in our Knowledge Hub.