Hemp fibres and hemp wood

Information of this showcase stems from another outreach inititive within the same theme of Transformative Bioeconomies programme. 

Source: Meeusen, M.J.G. en C.A.J. van Ruiten 2024, Opties voor de teelt van vezelgewassen voor biobased bouw materialen in de Nederlandse landbouw 

This page highlights the case of one specific crop, in this case hemp. Hemp is an annual crop and relativeley simple to cultivate. In this page more information can be found on charectristics of this crop, including its applications.

Hemp cultivation is relatively simple, but it does require specific harvesting mechanization and processing lines and is therefore geographically concentrated

Hemp is an annual arable crop. The cultivation of hemp is not complicated. Like grain, it is a rest crop with a relatively high production and a low need for labour/mechanisation, crop protection and nutrients. In principle, hemp can be grown on all kinds of soils, such as lighter clay, sand, löss and also peat soil. The crop is also seen as a soil improver with its extensive root system. The plant is sensitive to soil structure and waterlogging. The crop therefore requires well-drained plots.

The harvest is done with separate machines that most farmers do not have themselves. The harvest is therefore often carried out by contractors or processing companies. For this reason, cultivation is also concentrated in those areas where the processing industry is located. In 2024, there will be (two) hemp processing companies active in the Northern Netherlands, namely Hempflax and Dunagro. They take care of almost the entire cultivation and processing. About half of the production comes from Groningen, Friesland, and Drenthe are a close second; with about 300 hectares each.

When hemp is grown in other parts of the country, it must be transported over greater distances, which is associated with high transportation costs. For this reason, there are several initiatives to develop a mobile processing unit. This makes it possible to carry out the first processing step (separation of the long bark fibre from the woody core). The machine is not yet on the market – spring 2024 – but the prospects are promising. (presentation BouwBoeren event Building Balance, 7 March 2024). A stationary processing unit on a regional scale is also being considered, but that also requires further elaboration. 

In practice, we see that contractors and/or processors take care of a large part of the cultivation. The farmer is 'unburdened': tillage, sowing, harvesting and transport are carried out by the contractor/processor.

Different harvesting machines are used for the different (combinations of) components.  Torringa (2022) reports that this is not yet properly set up in the chain. 
The cultivation is mainly driven by the yields of the long fibre that find their way into higher-value applications: in the paper industry, in the automotive industry. The long fibre therefore provides the majority of the yields and determines the balance. 
Hemp is also being looked at as a textile fiber. Textiles as an application for the long fiber hemp are under further research. Hemp is then processed on the same machine as the flax. To do this, the hemp must be harvested differently; The long fibers must be kept parallel. In Belgium and France, there is a lot of experimentation going on. Two manufacturers have each developed a special harvesting machine. The long fibre can be used for textiles. We are at the beginning of a new development (nweurope.eu).
The economic value of the oil is not used in the Netherlands because the seed is not extracted in the Netherlands. Hemp ripens too late in the Netherlands. 

Arable farmer Peter de Schutter from Vierhuizen in Groningen is growing 20 hectares of fibre hemp for the first time on a total area of 250 hectares. He sees it as a product of the future.

'I had been looking for a fibre crop for some time. About five years ago, we insulated our house with fiber insulation. Because of the natural moisture regulation, you have a healthier living environment. It may be a little bit more expensive than other insulation materials, but it saves you an expensive ventilation system.'

De Schutter has considered flax as a fibre crop, but its cultivation is quite risky, partly because of retting, according to the grower.

'Fibre hemp is a very easy crop. You sow it late and it comes off early. I see it as a resting crop. It improves the soil. It needs little input, a little manure over it and it's done. It is a nice change in our building plan. We used to grow half of the grain. That's way too much. That will give you dead soil, it doesn't root deep enough. And it's too one-sided.'

The stems of the hemp plant have two components: the fibres (bark) and the wood (core). Both the longer bast fibre and the shorter (woody) hemp wood or shives can be used in construction, as a structural material or as insulation material.