CHCx3 Summer Update 2024
The Impact of Cover Crops on Soil Organic Carbon Pools
Recent research by Fohrafellner et al. (2024) provides new insights into how cover crops affect different soil organic carbon (SOC) pools in arable farmland across European climates. Their meta-analysis, which reviewed 71 studies published between 1990 and mid-2023, showed that cover crops significantly boost key components of soil carbon in the topsoil. These include mineral-associated organic carbon (MAOC), particulate organic carbon (POC), and microbial biomass carbon (MBC). Each of these plays an important role in soil health, with MAOC linked to long-term carbon storage and POC and MBC representing more active, labile carbon pools. The study also found that factors such as soil clay content, crop biomass, crop rotation, and tillage depth influenced how cover crops affect these carbon pools. While the research highlights areas where further long-term study is needed, it offers strong evidence that cover crops can enhance soil carbon sequestration and improve soil quality.
Reference: Fohrafellner, J., Keiblinger, K.M., Zechmeister-Boltenstern, S., Murugan, R., Spiegel, H., Valkama, E. (2024). Cover crops affect pool specific soil organic carbon in cropland – A meta-analysis. European Journal of Soil Science, 75(2), e13472. https://doi.org/10.1111/ejss.13472
Soil Carbon Storage Under Perennial Energy Crops
Recent global research has provided updated estimates on how perennial energy crops (PECs) contribute to storing carbon in the soil. A meta-analysis published by Wu et al. in Soil and Tillage Research (2024) found that, on average, PEC cultivation leads to a soil organic carbon (SOC) sequestration rate of 210 kilograms per hectare per year.
The study highlighted crop age and soil depth as the two most important factors influencing this rate. SOC accumulation increased with crop maturity, typically peaking around year nine before gradually declining. In terms of soil profile, deeper layers (30 to 60 centimetres) held more carbon than topsoil (0 to 30 centimetres), reinforcing the long-term value of deep-rooted perennial crops in carbon capture strategies.
These findings support the use of energy crops such as miscanthus and short rotation coppice as tools for improving soil health while helping to meet climate goals. As further research expands our understanding, perennial systems could play an increasingly important role in sustainable land management across the UK and beyond.
Reference: Yini Wu, Huarong Huang, Feng Chen, Tiansu Tan, Yi Xu. Soil organic carbon sequestration rate and spatiotemporal dynamics under perennial energy crops cultivation: a global meta-analysis. Soil and Tillage Research, Vol 240, 2024, 106064, ISSN 0167-1987, https://doi.org/10.1016/j.still.2024.106064
Bioenergy Crop Statistics in England and the UK
According to a new Defra report published in June 2024, bioenergy crops were grown on 133,000 hectares of agricultural land in the UK in 2023. The largest areas were devoted to wheat and sugar beet used for biofuels (45,000 ha and 2,600 ha, respectively), and maize used for anaerobic digestion (73,000 ha). Energy crops specifically grown for biomass, such as miscanthus and short rotation coppice (SRC), occupied smaller areas of 8,800 ha and 3,800 ha, respectively. Over the past six years, miscanthus cultivation in England has averaged just over 8,000 ha annually, with SRC (willow and poplar) covering about 3,000 ha. Including these crops alongside straw and other biomass sources, the UK used approximately 6.7 million tonnes of oil equivalent of plant biomass for electricity and heat production in 2022. Although this represents an 11% decrease from the previous year, it remains significantly higher than usage levels from 2010 to 2012.
