Industrial hemp could be a valuable tool in the box of UK agriculture, helping to transition to more sustainable practices, deliver on environmental public goods, and provide a new cash crop, say a group of farmers and researchers.

To investigate hemp’s potential further, five farmers are collaborating with researchers at Cranfield University and the British Hemp Alliance as part of an Innovative Farmers programme coordinated by the Soil Association. They plan to run on-farm field trials to gather science-based data about the plant’s environmental benefits.

Nature friendly farming benefits of hemp

Long stigmatised for being part of the Cannabis family (hemp varieties are low THC Cannabis Sativa L, and not used in narcotics), hemp does not require agro-chemicals, and there is growing international evidence that it can boost biodiversity, control pests, improve soils, and sequester carbon, say researchers.

It could also provide a useful break crop alternative to oil seed rape, which is becoming increasingly challenging to grow in the UK.

However, unlike many other countries, the UK still classifies industrial hemp as a ‘controlled drug’, and farmers wishing to grow the plant must apply to the Home Office for a license. Consequently, there are only about 20 licensed UK growers, totalling just 2,000ha.

“With post-Brexit agricultural policies focused on delivering public goods such as biodiversity and carbon sequestration, we need to look again at how we approach hemp in the UK,” said Nathaniel Loxley, Innovative Farmers project coordinator, and co-founder of the British Hemp Alliance.

“Hemp could be a very valuable tool in the box of British farmers, but the UK is currently behind the curve internationally and there is a distinct lack of data in the UK context,” says Mr Loxley. “We hope that by understanding hemp’s benefits better and collecting evidence on it, we can pave the way for more UK growers.”

A versatile plant

Industrial hemp is a versatile plant, used to make building materials, clothing textiles, animal bed-ding, and replace plastics. Manufacturers in the building, fashion and packaging sectors are increasingly looking towards the plant for ecological solutions.

The UK has a long history of growing hemp, and during Henry VIII’s rule it was so important for the British Navy (used to make sails and ropes, as well as cloth more generally) that it was illegal for land owners not to grow it. Henry Ford even built a car made from and run on hemp, and the plant was used to help remove contaminants from Chernobyl after the nuclear disaster.

“More and more benefits of this incredibly versatile plant are being discovered all the time,” says Helen Aldis, programme manager at Innovative Farmers. "There is a very real potential for British farmers to use hemp to regenerate their land, deliver on public goods, and grow a new cash crop, so it is fantastic that Innovative Farmers can be part of this. It is vital that farmers and re-searchers collaborate through these practical on-farm trials so we can discover the true environ-mental benefits of hemp, and share this knowledge with more growers."

Environmental benefits of hemp

A lot of the evidence about hemp’s environmental benefits is currently anecdotal or from a limited number of studies, coming from the USA and Europe, says Dr Lynda Deeks, a research fellow in soil science at Cranfield University, who has been looking at current research on the plant.

“It’s proven to be beneficial to the environment below and above ground, but it could potentially offer wider ecological benefits and this is what we need to understand,” says Dr Deeks.

One area Innovative Farmers will investigate is hemp’s potential to sequester carbon. The plant has potential to store carbon in the soil, and through the use of its fibres in bio-composite materials, such as for the construction or automotive industries, says Dr Deeks.

“Data from other studies has given differing rates of carbon sequestration, which is probably linked to soil types – so we need to know how this would apply in the UK context,” explains Dr Deeks.

“The plant also has a strong tap root, which could aid soil health through alleviating compaction, improving drainage and helping to aerate the soil. Ultimately when the roots decay the carbon should support a more resilient soil structure.”

Farmer perspectives on hemp

Innovative Farmers trial participant, Nick Voase is at the forefront of hemp growing and product innovation in the UK with his East Yorkshire Hemp company. He converted most of his farmland to growing the plant 15 years ago and currently has 450 acres down to hemp. Mr Voase processes the crop into fibre, animal bedding, HempLogz (fire briquettes), and ‘hempcrete’ (for construction).

“Although we’re not an organic farm, we grow hemp without any crop protection products, no seed treatment, nothing – it copes perfectly well without it,” says Mr Voase. “There are currently no fungal diseases or insect pests that do lots of damage.”

“This makes it very beneficial to insects, and at this time of year there’s often a cloud of swallows over the hemp,” he said. “I’m also interested in its potential to capture carbon – if we’re turning hemp into hempcrete we’re potentially locking up that carbon for as long as the building stands.”

Fellow Innovative Farmers trial grower, Camilla Hayselden-Ashby in Kent, is growing hemp for the first time on her family’s 320-acre mixed farm. She plans to add hemp to the farm’s rotation.

“Once hemp is established, it has a very dense canopy, so it shades out weeds – this attracted us to it as we have a black grass problem,” says Ms Hayselden-Ashby . “It’s roots also go down deep, so it brings up nutrients from further down and makes it available for future crops.

“I hope that by building data on the environmental benefits of hemp we will encourage the relaxation of the licensing around it. It’s not a dangerous drug, it is a plant with huge potential and farmers should be encouraged to grow it in the same way they are encouraged to grow legumes to improve soils.”

How the trial is being structured

The farms involved in the Innovative Farmers trial are all licensed hemp growers and have been chosen to represent a broad section of different climatic, topographic and soil conditions in the England.

They will grow industrial hemp over two plots, including a control plot, and will test their soils for organic carbon, soil structure, soil biology, and biomass nutrients. They will also run biodiversity surveys for butterflies, insects, and birds.

Pre-sowing preparation to achieve base line data, in currently underway.

The market for hemp

Hemp is an extremely versatile plant and has many uses, including:

- as ‘hempcrete’, a building material

- clothing fibres

- animal bedding

- mattress fillings

- alternative to glass fibre

- packaging/ plastics alternative

- paper

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Photo credits: Thank you to Joanne Crawford.