A group of six licensed hemp farmers are investigating the impact of hemp cultivation on soil health, carbon sequestration and both below and above-ground biodiversity.
As the UK transitions to ELMs payments based on a 'public money for public goods' approach, low-THC hemp is still classified as a controlled drug, so it is increasingly important for the growers to understand the value of the crop and gather data on its potential ecosystem services to further progressive policy around low-THC hemp.
There are many anecdotal benefits of growing the crop as a cash crop or break crop in arable rotations. For example, hemp's late flowering could help to fill the gap in pollen provision in the autumn, thereby supporting pollinators. Studies have referred to hemp's potential to sequester significant carbon as a fast-growing crop, however growers lack data to back up these claims.
Five farms will be supported by Cranfield University researchers to undertake assessments over two growing seasons, comparing different metrics pre-sowing and post-harvest. They will also be monitoring and comparing biodiversity in hemp fields to that of other crops in their rotation.
The farmers will be comparing the differences in the following metrics over time:
At the farm visit in July, entomologist Dr. David George from Newcastle University took us through some suggested ways to measure above-ground biodiversity. We agreed on the following protocol:
The group met at the farm at East Yorkshire Hemp in early July for a day of training. They also had the chance to visit the processing facilities, where the hemp is turned into fibre and the remainder is pressed into briquettes for fuel.
Lynda Deeks, soils researcher at Cranfield University, took the group through a 5-step guide for farmers/land managers to measure soil health, where each category receives a score, then tallied up for a final soil health score.
We undertook the assessments at the edge of a field as the hemp had grown tall so access to a more suitable spot for soil assessments was limited. However, the assessments will be done pre-sowing and post-harvest so a proper sampling procedure can be followed.
The group were trained on how to go about selecting sampling areas. When you select your sample area, have in mind the following:
For soil carbon samples:
Other soil health samples:
The following measurements will be taken on site by each farmer:
SOIL (change over time, before planting and after harvest)
Soil organic carbon (SOC) - using NRM's Soil Carbon Check service, sampling kits will be sent to the growers. They will collect 5 random samples at 0.3 metres deep across the representative area following a standard W pattern of sampling and send these off to NRM labs for analysis
Soil structure - using the visual soil assessment (VSA) which includes a range of soil properties (soil texture, soil structure), three random sampling points will be chosen within the representative area (coinciding with the SOC sampling points). Infiltration will be assessed using the single ring falling head method, to understand the main drainage and aeration channels through the soil. Three infiltration measurements will be taken at three of the VSA sampling points.
Soil biology - earthworm counts, including midden counts as a surrogate to indicate anecic earthworm activity. The group will follow AHDB's GreatSoils 'How to count earthworms' guide. All middens within a 1 metre radius of the VSA sample point will be collected.
Crop biomass - assessments of post-harvest biomass remaining in the field to understand nutrients available for next crop. This will be collected at the same sampling points as the SOC assessments and sent off to a laboratory for N,P and K assessments. NB: Laboratories require a license to handle hemp.
Above-ground biodiversity abundance - a simple walk through fields, counting and categorising insects, particularly pollinators or predatory insects, including larval/pupal stages.
Below-ground biodiversity = soil biology as above
This group comprises 5 licensed hemp farmers, spanning the UK from Jersey to Northumberland. Some of these are long-term hemp growers whilst others are planting for the first time this year. These project partners act as regional representatives within the UK for the first Innovative Farmers x British Hemp Alliance (BHA) Field Lab. The group are looking to participate in sampling and conducting on-site monitoring in order to produce more data on factors which are anecdotally known to be positively impacted by hemp cultivation, such as soil health, carbon sequestration and ‘biodiversity net gain’ and start to produce evidence of this impact.
Whilst the benefits of this crop are widely celebrated and offer huge potential opportunities for a “new” cash crop for British farmers, enhancing the supply of local protein, textiles and construction materials, there is little evidence available publicly to support the theory within the UK.
As the UK is transitioning from the EU CAP into the new Environmental Land Management scheme, the group want to represent the interests of hemp farmers and the potential correlation with ecological improvement. The considerable gap in scientific knowledge specific to UK hemp is hindering the UK hemp industries ability to lobby for better recognition of this crop’s potential in the sustainable soil and biodiversity arenas. Hemp is still classified as a 'controlled drug' in the UK and the farmers in this group have successfully navigated the current barriers of the ‘controlled drugs’ classification for low-THC Cannabis Sativa.
2nd May 2021
15th June 2021
30th June 2021
15th September 2021
15th October 2021
1st April 2022
15th April 2022
30th June 2022
15th September 2022
15th October 2022
British Hemp Alliance
Nathaniel is Founding Director of Vitality Hemp and Director of the British Hamp Alliance. His specialities include: the cultivation and production of Industrial Hemp in the UK,
Research and Development of new products and processes using various hemp raw materials, and developing a compliant industrial Cannabis brand. He is Director of a progressive Alliance within the UK representing hemp's Agricultural and Environmental opportunities.