Biomass crops like Miscanthus and willow are perennial, with a long life cycle, and can accumulate carbon underground each year.
They are planted on less productive UK land, meaning farmers can leave them to grow and concentrate on their productive fields to produce food.
Planting Miscanthus and willow is a good way to let land rest, recover, stabilise and store carbon over time, and it’s profitable. In the case of Miscanthus, crop specialist – Terravesta, has an established supply chain, to supply renewable energy power stations with locally grown crops.
Understanding underground carbon storage potential
To quantify the carbon storage potential of Miscanthus and willow, Dr Jason Kam and Alex McCash from Terravesta’s R&D department as well as a team led by David Marsh from Energy Crops Consultancy have begun taking soil samples this year.
“We are looking to answer two key questions with the sampling,” explains Jason. “Do these crops improve soil health? And how much carbon are they depositing in the soil?”
To do this, large-scale data collection, with soil sampling from commercial Miscanthus and willow crops has commenced this spring.
“Nine fields of Miscanthus and four of willow are being sampled. Some of these are newly planted and some are mature crops,” says Jason.
Samples taken are from the soil at particular depths. “We are testing for a ‘Visual Estimate of Soil Structure’ (VESS) of the top 30 cm; chemical analyses on 0-30 cm as well as 30-60 cm; and bulk density testing at 0-5 cm as well as 30-35 cm depth.
“So far, the top 30 cm of soil seems to be more favourable for plant growth than deeper layer, with a lower pH, higher potassium content, and a higher microbe score. Essentially, reflecting the presence of the root/rhizome structure benefits,” he says.
“Miscanthus has a deep root network that can go down to a meter, so it will be interesting to see if the lower 30-60cm structure also improves with time,” says Jason.
The hope is to test more Miscanthus and willow crops. “This year we have been hampered by the weather, which meant we had a limited window to conduct soil tests in.
“We are looking to improve the protocol and do more sampling of new and existing crops,” says Jason.
The soil sampling results are shared with NIAB for deeper analysis, and at this stage, Jason and Alex are collecting as much data as possible.
“Miscanthus is perennial, so it can store a lot of carbon over time and because of the deep root network, the plants have time to develop complex microbial communities and draw down carbon further into the soil, for potentially 20 years or more in the case of Miscanthus.
“We see this as important work, because we need to be able to quantify the benefits of Miscanthus and willow crops,” adds Jason.
