Industrial Hemp produces one of the most, if not the most industrially versatile and durable fibre known to humans. One hectare of Industrial Hemp grown for fibre, produces between 10 – 15 tonnes of biomass in a growth cycle of four months.
Hemp has a deep rooting system, and has a positive influence on the soil structure discouraging and nematodes and fungi. After cultivation, the soil is left in optimum conditions as a result of the complete weed suppression achieved through the high shading capacity of hemp. The crop is known to improve soils and to increase yields in subsequent crops such as wheat.
Industrial Hemp is bred from certified low THC varieties of hemp which have grown for thousands of years throughout Europe and Asia. Its closest botanical relative is hops. While hemp food crops have yet to be approved for human consumption in Australia, in most Australian states (with the exception of South Australian and the Northern Territory) licensed farmers can grow registered fibre varieties.
While Industrial Hemp needs a well prepared seed bed and adequate subsoil moisture, or irrigation for the first 6 weeks and produces optimal yields when it is irrigated, hemp fibre crops can be grown with less water than lucerne and produce a huge biomass. It is a very hardy crop and was identified early in the establishment of the colony as a suitable crop for Australian farmers.
When planted at appropriate densities for fibre production ( between 40 – 65 Kg seed per ha dependent on the variety), Hemp does not require the use of herbicides as the fast forming canopy excludes sunlight allowing the crop to outcompete emerging weeds.
Industrial hemp is grown successfully using organic farming methods in a number of countries, most notably Austria and Romania. Market demand and an emerging commitment to sustainable farming is now also positively influencing production in Australia.
Collaborative farming in NSW
A sustainable hemp building industry is dependent on regional Hemp production. Hemp fibre is very light and transporting a high volume, light weight material over long distances has a considerable impact on the life cycle analysis of any product. While freight is not yet commonly considered in Australian assessment of green building products, there is no doubt that it will be in the near future.
We currently source hemp from the closest possible location to our building projects and work collaboratively with farmers throughout Australia to support emerging regional Hemp farming groups.
The Carbon Picture
According to European research, where hemp is sustainably farmed 1.393 kg carbon dioxide is stored per kg hemp fibre.
While developing a soil carbon methodology for hemp is just being looked at in Australia, UK data has confirmed that hemp production sequesters 1 tonne of soil organic carbon per hectare.
Industrial hemp fibre crops produce 10-15 tonnes of dry fibre per hectare, so the tall rapidly growing biomass is ideal for carbon management projects. The harvested and dried stem yield is what is measured when assessing a crop’s capacity for carbon sequestration.
Hemp lime masonry locks up the fibre or captured carbon, to form a carbon sink. The building material then continues to take carbon dioxide out of the atmosphere as it slowly cures through the carbonation process.
Hemp as a Bioremediator
Industrial hemp has the capacity to clean up contaminated soils. European research (Karus and Leson, 1994) has demonstrated that hemp can be grown on soils contaminated with heavy metals, while the fiber remains virtually free of the metals.
Kozlowski et al. (1995) found that hemp grew very well on copper-contaminated soil in Poland (although seeds absorbed high levels of copper). Baraniecki (1997) found similar results.
The Mop Crop trial (Bolton, K., 2004) at Bangalow Sewage Treatment Works on the NSW North Coast has also proven hemp to be an excellent crop in the management of sewage effluent.