Sustainable agriculture is essential for a greener future and hemp has emerged as a key crop in this process. Its cultivation for the construction industry not only brings significant environmental benefits but also promotes responsible and regenerative farming practices.
The hemp plant
A strain of cannabis that contains very low proportions of tetrahydrocannabinol (THC), hemp is grown explicitly for its many commercial purposes.
Its cultivation is not a new concept by any means; it has been grown for centuries and has an astonishing 25,000 documented uses. However, with an increasing awareness of its valuable properties, it’s seeing a renaissance as a raw material in industrial applications.
In order to keep up with demand, farmers are being encouraged to add it to their crop mix, which means it has become a viable concern – in both practical and economic terms.
Whether it’s as an alternative crop or one grown alongside existing ones, hemp is extremely eco-friendly.
- It is very fast-growing and is ready to harvest in 3 to 4 months. Its biomass, which includes seeds, leaves and stalks, is abundant and can be used in numerous applications.
- It is a natural repellant and so doesn’t require interventions such as pesticides, fertilisers and herbicides, and it needs much less water – between 10% and 50% of that required by other crops.
- It decontaminates and replenishes soil, via phytoremediation, by filtering out toxic materials. As one of the least invasive methods, it doesn’t damage the environment in the process. It also helps in the reduction of weeds without the use of chemicals.
Carbon sequestration
Probably the most important aspect is that the plant is highly effective in carbon sequestration (the natural process of absorbing CO² from the atmosphere and storing it in its roots and stems).
One hectare captures the same amount of carbon as a young forest, but it only takes a few months to grow rather than several decades. The crop is also carbon negative, in that the carbon emitted in its harvest and processing is less than the amount it absorbs during its growth.
How to grow hemp for the construction industry
One of the most exciting uses of the crop is in the construction industry, with products like hempcrete building blocks. Commercially produced hemp specifically for the building industry is grown for the long dense stalks from which the “hurd” is derived (the inner core of the stem), rather than bushy ones, which are grown for the flowers and seeds of the plant.
To extract the hurd effectively, harvesting happens just before the plant fully flowers so it is removed before it reaches the phase when it draws most heavily on the nutrients in the soil.
Its properties of strength, flexibility, breathability and fire resistance mean that as an alternative building material it has huge advantages in terms of thermal insulation and sound absorption. In addition, the plant enriches the soil in which it is planted, making it an ideal crop for farmers who are concerned with regeneration of their land.
Harvesting and processing
The harvesting of hemp is not any different to other grains and doesn’t require any specialised equipment – although modification may be required to ensure machinery is not clogged due to the plant’s strong and, often, thick stems. Some farmers grow the crop for more than a single purpose: the stem will be harvested for its fibre and hurd whilst the tops will be used for the flowers and seeds. In those instances special machines have been developed to cut both at the same time and to initiate the processing.
For investment farmers who are not able or willing to invest in the machinery (which can be costly), there are options to partner with a company that will take on the production process.
Also, more and more countries in Europe are offering EU subsidies especially for hemp farmers, due to its highly positive environmental impact and carbon sequestration efficiency.
Hemp cultivation and usages are also planned to take an important role within the “European Green Deal”.
In 2024, Cânhamor will install the first industrial hemp processing factory on the Iberian Peninsula, to produce natural hemp blocks for use in sustainabçe construction.
This is a hugely exciting development for the hemp industry in Portugal, and a long-awaited incentive for farmers to consider the crop on a large scale.
