There was a happening in York recently – a Hemp Happening – organised by SCI’s Agrisciences Group and Biovale. It took place at York’s STEM Centre and explored the issues around growing and using industrial hemp. Despite these issues, there is a growing demand for hemp fibre and shiv as we look to use sustainable natural fibres and move to a low-carbon economy.

In 10 years’ time, you’ll walk out of your hemp-insulated home, wearing your hemp fibre t-shirt, polishing off the last of your hemp and beet burger, before heading to work in your hemp seed oil-powered car.

Is this scenario fantastical? Yes, obviously, but as delegates attending Hemp Happening explained on 6 April, all of these products exist right now. The sheer breadth of them underlines what a useful and versatile material hemp is. If enabled through policy, hemp could play a big part in our low-carbon future. Here are five ways it could make a significant difference.

1. Carbon sequestration

Hemp has much-vaunted carbon-sequestering potential which, given our climate change travails, could prove extremely useful. Some experts say it is even better at capturing atmospheric carbon than trees. According to SAC Consulting, industrial hemp absorbs nine to 13 tonnes of CO₂ per hectare. To put hemp’s absorption capacity into context, hemp market specialists Unyte Hemp said it absorbs 25 times more CO₂ than a forest of the same size.

Of course, that’s all very well, but how do you make sure this carbon remains sequestered?

2. A future heavyweight champion?

One fitting home for hemp (and the carbon it has captured) is in construction, especially given the carbon-intensive nature of the industry. So, with the pressure intensifying to replace and retrofit the UK’s inefficient building stock, hemp is well placed to reduce emissions and improve building performance.

Hemp is not just used in insulation materials due to its excellent thermal performance characteristics. It is also used in rendering buildings and for non-load bearing blocks in construction. Indeed, hempcrete blocks, which are made from hemp shiv, lime, and sand or pozzolans, have a net carbon negative footprint.

Hemp is used in everything from food supplements to medicines, cosmetics, and construction products.

3. Farmer’s friend

Hemp also helps the earth. As flash flooding strips our soils, the plant’s root density and deep structure protects against soil erosion and mitigates compaction. Hemp also provides nutrients to help maintain soil health, making it useful in crop rotation.

As insect populations dwindle, the role of pesticides and herbicides are coming into sharper relief. In that respect, hemp has a natural advantage over other crops as it doesn’t require pesticides and fertilisers.

4.The Swiss Army knife of materials

We have long heard of the health benefits of hemp-derived products such as cannabidiol oil (or CBD oil), but pretty much the whole plant can be used. Its seeds are rich in omega-3, omega-6, and fatty acids, and help fend heart problems.

As mentioned above, the fibrous part of the plant sequesters carbon and produces low-carbon materials for construction, while its roots are used to treat joint pain and for deep tissue healing.

And then we have hemp for bioethanol production and even hemp seed veggie burgers. The list goes on; so, there are many ways for farmers to make money from it.

>> What can be done to make our soils healthier? Take a look at our blog on solving soil degradation.

Hemp has excellent insulation properties.

5. Non-thirsty textiles

I bet you know at least one person with a bamboo t-shirt or socks. Hemp has similar textile potential to its super material cousin. As the fashion industry interrogates its wayward past, the pressure will increase to lighten the footprint of clothing materials. Estimates vary, but hemp is said to need less than half the water required to cultivate and process than cotton textiles and its toughness is handy in long-lasting carpeting.

Mr Elephant, could you step through please?

Hemp has been heralded as a wonder material for decades but there is that elephant in the room. The restricted uses of hemp-related materials curb the extent to which it can be grown in the UK. At the event, delegates noted that outdated legislation, lack of government support, and education are among the factors holding back the growth of hemp on an industrial scale.

And yet, there is growing demand for natural materials that tackle climate change, especially those that sequester carbon. With pension funds increasingly divesting from fossil fuels, and the ever growing importance of corporate sustainability in business, sustainable materials such as hemp are now more attractive.

Arguably the most exciting contribution of the day was the mention of zero-cannabinoid industrial hemp. Even though the THC content levels present in hemp are low (compared to the high levels found in marijuana) and it’s unattractive as a THC source, hemp is still very strictly regulated in the UK compared to North America and the rest of the EU.

One participant mentioned that hemp genes could be edited to remove the cannabinoid – and, if that were to be achieved, it could change everything. Then we would really see hemp happening in the UK.

>> Interested in more events like this one? Visit our Events pages.

How much soil cultivation do you need for your vegetables? Professor Geoff Dixon explains all.

Cultivating soil is as old as horticulture itself. Basically, three processes have evolved over time. Primary cultivation involves inversion which buries weeds, adds organic matter and breaks up the soil profile, encouraging aeration and avoiding waterlogging.

Secondary cultivation prepares a fine tilth as a bed for sowing small seeded crops such as carrots or beetroot. In the growing season, tertiary cultivation maintains weed control, preventing competition for resources (illustration no. 1) such as light, nutrients and water while discouraging pest and disease damage.

Lettuce and seed competition

The onset of rapid climate change encouraged by industrialisation has focused attention on preventing the release of carbon dioxide into the atmosphere. Ploughing disturbs the soil profile and accelerates the loss of carbon dioxide from soil.

It is also an energy intensive process. Consequently, many broad acre agricultural crops such as cereals, oilseed rape and sugar beet are now drilled directly without previous primary cultivation. An added advantage is that stubble from previous crops remains in situ over winter, offering food sources for birds. The disadvantages of direct drilling are: increased likelihood of soil waterlogging and reduced opportunities for building organic fertility by adding farmyard manure or well-made composts.

Overall, primary and secondary cultivation benefit vegetable growing. The areas of land involved are far smaller and the crops are grown very intensively. Vegetables require high fertility, weed-free soil, good drainage and minimal accumulation of soil-borne pests and diseases.

Frost action breaking down soil clods

Digging increases each of these benefits and provides healthy physical exercise and mental stimulation. Frost action on well-dug soil breaks down the clods (illustration no. 2). Ultimately, fine seed beds are produced by secondary cultivation (illustration no. 3), which encourage rapid germination and even growth of root and salad crops.

Tertiary cultivation to prevent weed competition is also of paramount importance for vegetable crops. Competition in their early growth stages weakens the quality of root and leafy vegetables, destroying much of their dietary value. Regular hoeing and hand removal of weeds are necessities in the vegetable garden.

Raking down soil producing a fine tilth

Ornamental and fruit gardens similarly benefit from tertiary cultivation. Weeds not only provide competition but are also unsightly, destroying the visual image and psychological satisfaction of these areas.

Lightly forking over these areas in spring and autumn encourages water percolation and root aeration. Once established, ornamental herbaceous perennials and soft and top fruit areas benefit greatly from the addition of organic top dressings. Over several seasons these will augment fertility and nutrient availability.

Written by Professor Geoff Dixon, author of Garden practices and their science, published by Routledge 2019.

Gardens in December should, provided the weather allows, be hives of activity and interest. Many trees and shrubs, especially Roseaceous types, offer food supplies especially for migrating birds.

Cotoneaster (see image below) provides copious fruit for migrating redwings and waxwings as well as resident blackbirds. This is a widely spread genus, coming from Asia, Europe and northern Africa.

Cultivated as a hedge, it forms thick, dense, semi-evergreen growth that soaks up air pollution. In late spring, its white flowers are nectar plants for brimstone and red admiral butterflies and larval food for moths. Children and pets, however, should be guided away from the attractive red berries.

Cotonester franchetti | Image credit: Professor Geoff Dixon.

Medlars (Mespilus germanica) offer the last fruit harvest of the season (see image below). These small trees produce hard, round, brownish fruit that require frosting to encourage softening (bletting).

Its soft fruit can be scooped out and eaten raw and the taste is not dissimilar to dates. Alternatively, medlar fruit can be baked or roasted and, when turned into jams and jellies, they are delicious, especially spread on warm scones.

Like most rosaceous fruit, medlars are nutritionally very rich in amino acids, tannins, carotene, vitamins C and B and several beneficial minerals. As rich sources of antioxidants medlars also help reduce the risks of atherosclerosis and diabetes.

Medlar fruit (Mespilus germanica) can be turned into jams and jellies | Image credit: Professor Geoff Dixon.

Garden work continues through December. It is a time for removing dead leaves and stems from herbaceous perennials, lightly forking through the top soil and adding granular fertilisers with high potassium and phosphate content.

Top fruit trees gain from winter pruning, which opens out their structure, allowing air circulation when fully laden with leaves, flowers and fruit. Fertiliser will feed and encourage fresh root formation as spring progresses.

The vegetable garden is best served by digging and incorporating farm yard manure or well-rotted compost, which adds fertility and encourages worm populations. The process of digging is also a highly beneficial exercise for the gardener (see illustration no 3).

Turning the soil isn’t only good for your garden - it boosts your wellbeing | Image credit: Professor Geoff Dixon.

Developing a rhythm with this task supports healthy blood circulation and, psychologically, provides huge mental satisfaction in seeing a weedy plot transformed into rows of well-turned bare earth.

When the weather turns wet, windy and wintery it provides opportunities for cleaning, oiling and sharpening tools, inspecting stored fruit and the roots of dahlias kept in frost-proof conditions.

Finally, there is always the very relaxing and pleasant task of reading through seed and plant catalogues and planning what may be grown in the coming seasons.

Written by Professor Geoff Dixon, author of Garden practices and their science, published by Routledge 2019.