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Industrial Hemp

Industrial Hemp-R&D in S.A.

by John Hannay, Program Manager, Pulse and New Crops PISA, and Caroline Graham Horticultural Development Manager Yorke Regional Development Board

 

Until the late nineteenth century industrial hemp (Cannabis sativa L.) was one of the world's largest agricultural crops and the most traded commodity.

It was grown for the production of fibre and seed. Because of its fibre strength, it was the preferred source of fibre for the manufacture of rope, fabric and paper, while oil was extracted from the seed.

With the mechanisation of cotton processing, it became the main fibre source, while the decline of sailing ships decreased the market for rope and canvas sails. This decline continued in the 1930s and 1940s with the introduction of synthetic fibres such as nylon.

Drug prohibition laws do not discriminate between low and high narcotic varieties of hemp and in the early to mid 1900s laws were introduced making hemp cultivation illegal in Australia and many other countries.

By the early 1990s the total world hemp crop covered just 290,000ha, with China, the Ukraine and Eastern Europe the main production areas.

Industrial Hemp and Marijuana

Industrial hemp is grown as a fibre crop while marijuana or psychotropic hemp is grown for the narcotic cannabis. Both are forms of Cannabis sativa L. The important difference between the two forms is the level of the narcotic tetrahydrocannabinol (THC). In industrial hemp the THC level is less than 0.3 per cent compared with between 3 and 10 per cent in narcotic hemp. Industrial hemp cannot be used as a substitute for marijuana as its THC content is too low to produce any psychotropic effect. Although industrial hemp is taller and less branched than marijuana, the visual appearance of both plants is essentially similar.

A New Age for Industrial Hemp

During the past decade there has been a world wide resurgence of interest in hemp for production of paper, textiles and a range of industrial uses. Most of the current hemp research and commercial development programs focus on the potential of hemp for paper manufacture.

In Europe, in particular, the use of non-wood plant fibres such as industrial hemp, flax, wheaten straw and fast- growing woods as raw materials for producing paper are attracting attention.

South Australia's Prospects for a New Industry

This year the South Australian Government granted a licence issued under Section 56 of the Controlled Substances Act.

The main emphasis in the SA programs will be on the production of fibre for paper. However, other opportunities will also be considered.

It will take a number of years to determine the agronomy of industrial hemp and its suitability to SA conditions. From the crop research and development program that began in SA in March the SA Government will then be in a position to decide whether a commercial industrial hemp industry in SA should proceed. Until then, licences for commercial production will not be issued.

Under South Australian legislation, marijuana or industrial hemp (Cannabis sativa L.), is classified by the Controlled Substances Act as a prohibited substance and cultivation of either form is totally prohibited.

To enable the potential of industrial hemp under SA conditions to be evaluated a research licence has been issued under Section 56 of the Act to the Yorke Regional Development Board with the research being conducted by South Australian Research and Development Institute and IAMA Technical Services. The licences will be renewable annually by the SA Health Commission subject to stringent security conditions and in accordance with an agreed trial protocol.

The Hemp Plant

Industrial hemp is a tall, annual herbaceous plant with a deep tap root it grows to a height of 1 to 4 m high, depending on variety and growing conditions. It has a single slender main stem and when grown at commercial crop densities the stems are generally unbranched. Stem thickness varies from 4 to 20mm in diameter.

Hemp is normally dioecious, meaning it has separate male and female plants, but monoecious varieties have been bred. The seed is small, brown to grey in colour and has an oil content of about 35% and a protein content of 25%.

Stem Composition and Processing

The stem fibres can be divided into two very different types of fibres, the bark or bast comprising the outer stem tissues and the core or hurd consisting of the inner stem tissues.

The bark or bast contains primary and secondary bast fibres, which are thick walled, have a high cellulose and a low hemicellulose and lignin content. Primary bast fibres are 5-50mm long, while secondary bast fibres are shorter, being about 2mm long and are more lignified. Primary bast fibres are about 34 mm and secondary bast fibres about 17 mm wide. The bast composition is approximately 67% cellulose, 13% hemicellulose and 4% lignin. Bast comprises 30-35% of the stem dry matter. As the bast is the most valuable component for paper or textile production bast fibre quality is of prime importance.

The woody core fibres are thin walled (average 2 mm) and are short (0.55 mm) and have a chemical composition which resembles hardwood being approximately 40% cellulose, 20% hemicellulose and 20% lignin.

Paper production requires high quality bast and hurd fibre having a long fibre length, a high cellulose content and a low lignin content.

Hemp is used to produce specialty printing and writing papers or as an additive to strengthen and improve quality in wood and straw-based paper manufacture.

Growing Requirements

Hemp is a short-day plant and is usually spring sown. Crop development and flowering of short day plants is hastened by short-days and delayed by long days. When planted in autumn hemp will tend to flower and set seed without producing the long stem lengths required for fibre production. There are varietal differences and the SA research program will be evaluating varieties that are less photo-period sensitive and better adapted to winter sowing.

The plant is best suited to well structured neutral to alkaline clay and loam soils with good water holding capacity which are not subject to waterlogging.

Although susceptible to early weed competition, the tall growth habit and high plant density enables hemp to compete well with weeds. European experience suggests hemp is less prone to pests and diseases than many other crops.

Yields under SA dryland conditions have yet to be established.

Harvesting

Harvesting for paper pulp and textiles occurs at the end of flowering of the female plants and before seed formation. The process is similar to making hay. The crop is cut with a mower or windrower, left to ret or dry in the paddock for several days if it is to be used for paper products and several weeks where it is destined for textile usage. When the moisture content has fallen under 15% it is baled into round bales and then taken to storage.

South Australia's Research and Development Program

The SA industry development program to determine the agronomic and the market potential of industrial hemp has been initiated by the Yorke Regional Development Board which is coordinating and managing a number of collaborating agencies, including representatives from the Yorke Regional Development Board, SA Research and Development Institute (SARDI), Primary Industries South Australia (PISA), the SA Health Commission and the SA Drug Task Force.

During 1995 three research trials representing a range of climatic and soil conditions will be conducted. These trials are designed to assess the agronomic requirements of the crop and determine whether economic yields can be achieved under South Australian conditions.

The trials are located at Turretfield Research Centre in the Lower North, Kybolite in the South East and Arthurton on Yorke Peninsula with the trial work being undertaken by SARDI and IAMA Technical Services.

The trials are evaluating five French cultivars sown at monthly intervals between May and October. The five varieties are Ferimon, Fedora 19, Felina 34, Fredrina 74 and Futura 77.

All trials will be grown under dryland conditions. The annual rainfall at Turretfield Research Centre is 460mm, at Arthurton 450mm and at Kybolite 600mm. Irrigated trials will be part of the varietal assessment at Kybolite.

The cultivars will be evaluated for:

  • THC levels
  • growth rates
  • water requirements
  • photoperiod response
  • fibre quality
  • soil type requirements

The trial program will be expanded in 1996-97 to include agronomic research on seeding rates, fertiliser requirements, insect and disease management and weed control.

Marketing Research and Development

The Yorke Regional Development Board has received funding from the SA Economic Development Authority to conduct a feasibility study on end use, market potential and requirements of processors. A report detailing the results of the study will be available upon its completion in January 1996.

[ Source : http://www.newcrops.uq.edu.au/newslett/ncnl4144.htm