HempCyberFarm Answer 8

Answer 8 Harvesting Techniques
Processing of Hemp and this page

Harvest Picture courtesy of Ecolution® in Romania

Harvest Picture courtesy of MotherHemp Ltd.

note: these pictures below have been made available to us by Anton Holler at; http://www.holler-deggendorf.de

Please click here for a pictoral overview

8. Harvesting & processing methods and machines to use:

Harvesting technique and preservation: Field tests were carried out with a cutter bar, a mower conditioner, balers, field choppers and a decorticator. All machines, except the decorticator, are commonly used in other crops. When relevant and necessary, minor adaptions were made to make them suitable for hemp. The main objective of the field tests was to learn and solve the difficulties in handling a fibre hemp crop utilizing different techniques.

We investigated the possibility of wet preservation by anaerobic storage. The hemp stems were cut in short pieces (1 cm) and preserved in bottles of 1.5 l capacity. After flushing with nitrogen, the bottles were closed air tight. To create different environments, we used the following additives: Foraform (Barenbrug Holland BV), a silage additive consisting primarily (92%) of formic acid; kitchen salt; sodium hydroxide; and Silage inoculant 1188 (Pioneer Hi-bred Nederland BV), a silage additive containing Lactobacillus plantarum and Streptococcus facium. After preservation, pH was measured of a 1:10 aquatic extract. The cellulose and hemicellulose sugars and the lignin were determined using an analysis derived from TAPPI-249 and TAPPI-222 (de Maeyer and Huisman 1994). Bast fibres were cooked for 1 hour in a 2% sodium hydroxide solution and the strength was measured in a controlled environment (23° C, relative humidity 50%) with a stelometer according to ASTM D-1445 (ASTM 1967).

Separation of bark and core: We used 3 methods to separate bark and core: decortication of green stems in the field, sieving of chopped stems, and flotation of chopped stems. The decorticator broke the core of whole stems and beat the core pieces from the bark. The sieving and flotation of chopped stems were done after a 6 month wet preservation period. The sieve dimensions were 2 x 4 cm. With flotation, the hemp was thrown into a bath of slow moving water in which part of the pieces floated and the rest sank. By measuring bark and core masses, we determined the efficiency of each operation.

Information is available from the following trials; Tasmania, Australia:
Harvesting methods that I would like to describe are currently under development. I hope to enlist the help of Hemp producing/growing companies to shed some light on this. In essence, this is the point of my site on the net. I would like this site to serve as a research platform for current (harvesting) techniques. So far I have read articles on the traditional Hemp producing countries of which China takes the lead. In fact, China has been a producer of Hemp for more than 5,000 years. In all probability Hemp as a resource for raw material h

A cooperative research effort involving the Department of Agricultural Science, University of Tasmania and Australian Newsprint Mills Ltd. started in early 1994:

It is believed that the relatively long, dry nature of the Australian growing season (at 147°30'E 42°50'S) and existing equipment is best suited to a 'dry' harvest system where the straw is dried naturally in the field prior to collection. The crop was allowed to proceed through seed maturity to assess dual purpose potential.

Please note: This trial was set up with a dual purpose; Hemp-seed and fiber production. It may be obvious that this dual purpose makes the harvest even more complicated. Thus, this trial has a limited validity as a real-life situation where crops are destined to yield either seed or fiber. I would like to remark though, that it is good to try things that haven't been done before. It is conceivable that dual purpose crops will be grown at some point in the near future. For now, more trials have to be conducted and in the process more problems will be solved.

A range of equipment was trialled including a combine harvester, finger mower, draper style windrower, ground driven rake, round baler and chaff cutter. The conventional combine harvester was able to take seed off, but only by raising the cutter bar to the maximum allowable height of approximately 180cm = 6 feet. At this cutting height, more than the seed bearing portion of the stem was removed resulting in fiber losses.

In order to optimize the efficiency of the seed harvesting operation, timing is vital and even with good timing the efficiency is expected to be low due to the non-uniform nature of seed maturity. Other potential problems with a dual purpose hemp crop (see note above) include contamination from leaf and residual seed in the paper-making process, losses of stem yield in the wheel tracks, prolonged security risks and some potential risk associated with the inadequate drying of the stem late in the season. A more appropriate system might involve separate seed and fiber crops, managed in such a way as to optimize the yield and quality of each crop product.

Having removed the seed, the remaining stem was then mown near ground level with a finger mower. The narrow draper style windrower was clearly unsatisfactory for handling tall Hemp crops. Existing wide draper or augur type windrowing equipment designed for other crops may prove satisfactory for Hemp harvesting.

No major problems were encountered with the round baling of the stem. Minor pickup blockages can be overcome by careful selection of groundspeed and a reduction in windrow volume.

In order to overcome problems with fiber tangling in the pulping of Hemp, the stem or bark fiber will need to be cut into lenths of 5-10mm = ¼ to ½ inch. With this in mind, it was felt that another possible harvesting option might be to pass the stem through a modified forage harvester and feed the cut straw into a hopper bin. To assess this, retted and unretted stem material was passed through a stationary five-bladed chaff cutter. A more uniform cutting length could be achieved by ensuring the stem is fed end on to the cutter, by minimizing the gap between blade and cutting face, having sharp blades and employing a sieving table with feedback of over-long pieces. The action of cutting seemed to separate the bark and core fractions quite effectively.

Processing of Hemp

Natural Fiber Processing Baden/Badische Naturfaseraufbereitung GmbH
Verarbeitung von Hanf und anderen nachwachsenden Rohstoffen

BaFa Badische Naturfaseraufbereitung GmbH - Stephanstr. 2 - 76316 Malsch
Geschäftsführer:
Bernd Frank
Peter Muthmann
Tel.: 07246/942374
Fax: 07246/942376
Email: bafa@karlsruhe.netsurf.de

Do you know more about this? E-mail us at Matthew@HempWorld.com

*Industrial-Hemp has no psychoactive properties following definition of the European Economic Community (EEC); THC content is less than 0.3%. In general, low THC-seed varieties without psychoactive properties are those that have a THC content of less than 1%. (See also No-THC Hemp-seed.) THC= Delta-9 TetraHydroCannabinol.