Promoting the Economic, Environmental, Health and Social Benefits of a NZ Hemp Industry


Photo courtesy of Struan Christie, Harvest March 2013006008

Photo courtesy of Struan Christie, Ashburton harvest March 2013





Many countries around the world currently grow Industrial Hemp, These include those who have continually grown hemp such as China, France, India, Rumania, Hungry, North Korea, Ukraine and Russia, while other countries have only recently begun researching a hemp Industry.

These include England (1993), Holland, Germany (1995), Canada (1994), Australia (1990), New Zealand (2002) (dates shown indicate years in which these countries began their trials).

Hemp is an ideal rotation crop helping to break up and condition the soil for following crops due to its long root structure penetrating deep into the soil when fully matured, this helps aerate the soil.

Significant amounts of heavy metals have been removed from polluted ground by hemp crops in Poland and other Eastern European countries.


Whilst it is true that HEMP is grown in small plots in so called under-developed countries with no fertiliser, often in poor soils, with meaningful results, the reality is that Hemp (Cannabis Sativa L) is not a nitrogen fixer, and to produce on the scale necessary to make it an economically viable crop in the modern world Hemp requires finely tilthed soils, rich in organic matter.

Industrial Hemp requires nitrogen, phosphorous & potassium to produce maximum economic returns. Of course all these facts are gross generalisations. Specifically developed genotypes have been produced in Russia and Hungary that require minimal or no fertiliser. The real facts appear to be if you farm it you have to look after it & its home i.e. the soil.

“Hemp seems to be an attractive crop for a sustainable agricultural system, as it has moderate fertiliser requirements, needs little or no pesticides and suppresses weeds and some major soil-borne pathogens.

Cannabis is certainly a valuable crop plant, and its future success will depend in part on the responsible dissemination of accurate information concerning its benefits.


To achieve an optimum hemp yield, twice as much nutrient must be available to the crop as will finally be removed from the soil at harvest. A hemp field produces a very large bulk of plant material in a short vegetative period. The nitrogen uptake is most intensive the first 6 to 8 weeks, while potassium and in particular phosphorous are needed more during flowering and seed formation. Industrial hemp requires

105 to 130 lbs/ac (120 to 150 kg/ha) nitrogen,

45 to 70 lbs/ac (50 to 80 kg/ha) phosphate and

52 to 70 lbs/ac (60 to 80 kg/ha) potash.



The Cultivar Question?

Well of course it will, but will it produce economically viable, usable & uniform raw materials, would be a more pertinent question. Hemp is grown in mountainous regions of Morocco & is a viable agricultural crop there.  The biodiversity question as it relates to Industrial Hemp seedstock is further compounded by western bureaucracies insisting on no more than 0.3% THC (tetrahydrocannabinol), the psychoactive ingredient of Marijuana, content in the mature plant.  The European Union has only approved 12 cultivars to date (approximately 600 germ plasms are held at the Valisov Institute), the majority of which are French, which is no surprise as they have been growing Industrial Hemp nonstop for hundreds of years. This of course gave the French a virtual monopoly on Industrial Hemp seedstock until very recently.  At least two issues are currently confronting this situation; the Swiss, tired of this artificial monopoly, implemented a policy whereby provided you signed a statutory declaration stating that you would only utilise the crop for industrial purposes, you could grow whatever Hemp cultivar you liked.  This has been a boon to Swiss farmers, who are enjoying increased Industrial Hemp production.

The second issue is in the European Union, Australia, England & Canada, Industrial Hemp farmers & researchers are pushing for a more realistic figure of 1 to 1.5% THC content in the mature plant. Given that the authorities generally recognise that for Marijuana to have any effect on human beings it must have 3-18% THC content, this proposal seems imminently logical.

Another problem faced by embryonic Industrial Hemp producers/farmers is the high cost of approved cultivar seedstock, in general terms it is possible to purchase Industrial Hemp seedstock for as low as USD$500 per tonne, but realistically it costs about USD$2500 per tonne at the time of writing, combine this with two other factors, high cost of transportation & a requirement to harvest the crop (Australia/Canada) prior to seed formation, means that farmers in New Zealand/ Canada/Australia, under those conditions will NEVER have acclimatised (generally recognised as 3- 4 generations) seedstock nor genotypes bred for specific product end usage requirements in their particular geographic location. This has very dramatic effects on the economic models produced by these TRIAL crops. An Industrial Hemp trial crop from seedstock not acclimatised will never give a representative picture of the crops economic potential. The real value of trial crops realistically should be to produce cultivars suitable for local conditions.

We are talking optimum performance of known commercial cultivars here. As there is no acclimatised seedstock specifically designed for New Zealand soil types, trial crops will really only set a precedent to allow politicians & bureaucracy to become comfortable with their legislative requirements & add an onerous but unavoidable cost to early participants. Industrial hemp is sensitive to soil compaction and waterlogged soil conditions.


Hemp should not be planted until soil temperatures reach at least 6- 8°C, in the first month or so. The seedlings require 3-4 inches of rain or irrigation, during this first month of growth, 25-30 inches rainfall per annum. As they grow larger these requirements drop dramatically due to the dense canopy enabling water retention and the deep taproot seeking out the water table. Industrial Hemp is frost tolerant. Hemp tolerates temperature extremes. In the drier regions of New Zealand suitable for growing Industrial Hemp such as  Canterbury, Tasman & Hawkes Bay it is highly likely that irrigation would be necessary.


The International Hemp Association has published a two-part review identifying over 300 insect pests.

JOHN MCPARTLAND WROTE: “Cannabis has a reputation for being pest free.  Actually, it is pest tolerant. Most Cannabis pests are insects. Nearly three hundred insect pests have been described on Hemp & Marijuana, but very few cause economic crop losses”.

FURTHER ON HE STATES: “The claim that Cannabis has no diseases is not correct. Cannabis suffers over one hundred diseases, but less than a dozen are serious”.



Yes it does!

Every text on hemp going back thousands of years see “Marihuana The First Twelve Thousand Years” by Ernest L Abel which describes in detail the smothering ability of Hemp. There is however one  catch whereby the plant is vulnerable at the seedling stage.

Once it is a week or two old, provided the strike rate has been high & evenly distributed, NOTHING seems to be able to compete. Hemp has been successfully used as a smother crop throughout history. Even when grown as a seed crop at a density of one or two plants per square meter Hemp shows this ability to smother other plant life.

The Chinese have a seed variety with seeds produced in abundance the size of small peas & reportedly use NO herbicides.


There is some debate on this, given that the plant is and has been grown throughout the world in all sorts of soil & climatic conditions. A fair assessment would be that Industrial Hemp is global in distribution with regional specific cultivars obviously performing well in their regions of origin. In the New Zealand context as an agricultural crop, Hemp is more suited to temperate climates, with reasonable rainfalls (3-4 inches per month). The further from the equator the better as Hemp is light / daylength sensitive.  Seeding / flowering needs to be delayed as long as possible for optimum economic returns, unless being grown specifically for seed production. The onset of the reproductive phase significantly reduces the quality of fibre produced. Fibre quality is also reduced by heat but increased by wind provided it is not too strong. In hot, dry climates, as a rule of thumb, Hemp produces more resin & poorer quality fibre. In mild humid climates less resin is produced, the fibre is stronger & more durable.

This means unless cultivars are specifically developed for the conditions, potential Hemp growers in Canterbury, Tasman / Motueka & similar climatic areas in New Zealand would be unwise to place too much reliance on the Hemp fibre. They would be wiser in the first instance at least to concentrate on Hemp seed (a much higher value crop anyway) and producing cultivars specifically for their region. This raises another somewhat interesting point. Seed produced in say Canterbury will not be a good seedstock for Southland due to soil and climatic differences.

This means that any New Zealand region seeing itself as the seed stock supplier for the rest of the country would be wise indeed to revisit this prognosis and review it very critically. We are not saying that this is not a possibility, we are simply stating that all available evidence shows that best economic returns are generated from acclimatised regional specific cultivars. Alternatively, whole coarse fibre could be the desired end use as Australian Hemp Resource and Manufacture (AHRM) are promoting in Australia, where the quality of the fibres such as is required for clothing, fabric, etc, is not as critical.


The Cannabis genre indeed has both male & female plants. This is the plant’s natural state and is called dioecious, which means the male and female are separate plants. Throughout history it has been known that the male plant has superior, finer, stronger fibre.

The male plant bears the pollen, the female the seeds. Fibre quality reduces significantly once the reproductive process starts. Unfortunately the male plant usually starts the process before the female & once the male’s flowering is complete the male plant dies. In earlier times male plants were ‘pulled’ separately, a very labour-intensive job, in order to get the superior fibre. It is worth noting that only the female plant is considered useful by marijuana growers, the male plant is pulled and discarded for fear of pollinating the female & thus reducing the female’s THC content. Authorities should note this fact as in the NZHIAI view it demonstrates the futility of attempting to produce marijuana in industrial Hemp crops. A Russian hemp breeder first recognised the advantages of a monoecious hemp cultivar; an artificial cultivar that has both male and female on the same plant. It’s advantages are higher seed production and uniformity of crop readiness for harvest. The disadvantages are that it requires annual breeding selection, as in progressive plantings it regresses to the dioecious state, produces less seed in successive generations and has slightly inferior fibre to correctly harvested dioecious varieties from the onset.

There is a third type artificially created that is a female predominant variety (for seed production). This occurs by pollinating dioecious females with monoecious pollen. Irrespective of which cultivar is used, in a farming situation seedstock for the following year must be carefully bred by seedstock specialists as the plant diverges quite markedly from its parents if allowed i.e. there is a natural wide diversity of characteristics.


Cannabis Sativa L, Industrial Hemp in its natural state (wild) is a low THC plant. Scientific analysis of ‘wild’ hemp in the USA,Vietnam & Australia show an average THC content of 0.6%.  The Hunter Valley discoveries of wild hemp in Australia in the 60’s are thought to be left over from early attempts at Hemp farming in Australia. In many states in the USA there still grows wild hemp, called ditchweed, with negligible THC content, left over from commercial crops grown in the 1930 and 1940’s. Quite obviously they have not reverted to high THC.  Vietnam has wild hemp growing in most of the country. It provides villagers with a useful income, is harvested, processed and woven by hand to produce narrow long bolts of rough but appealing cloth.

“Hemp is naturally a low THC plant with wild-types averaging a THC content of 0.6%. It is only through intensive selection that high THC cultivars are maintained. In addition, the genetic expression of THC can be very readily reduced and ‘fixed’ at a low THC. Hemp is fertilised through outcrossing whereby pollen is carried for kilometres by wind.


Harvesting time is dependent on end usage. Hemp is harvested prior to seeding for the strongest fibres, or when the seeds are mature for multi purpose crop. The crop is hard on conventional farm machinery & some minor modifications are required due to the long stalk length and its toughness.

Sickle side cutters (forage harvesters?) are used in combination with big square or round bailers.

No doubt as the crop develops worldwide the appropriate Modern machinery will be developed.  For now traditional machinery does the job, if somewhat onerously.

Harvesting for high quality fibre takes place as soon as pollen is shed, 70 – 90 days after sowing, although this varies greatly dependant on cultivars and location. For seed 4- 6 weeks later, (when 60% of the seed is ripe).


Dew retting (a microbial decay of pectin, the substance that glues the outer fibre to the inner woody core) in the field is possibly the most commonly used traditional method of separating the outer stalk fibres from the inner woody core (hurd). This is weather dependant and should be completed with several machine turnings of the stalks (similar to hay) within 12 to 18 days.

Other methods used in the past, such as pond retting or stream retting, which use moisture and bacteria to complete the process are not practical or possible in modern times. There are many methods of decorticating now being developed, such as steam explosion and ultrasound.

Possibly machines such as the transportable Hill Agriculture decorticator are more attractive as the other methods require transport of the crop as it is cut and therefore very bulky.

Recently the potential of an Australian machine has been investigated in New Zealand,  the D8 mobile decorticator developed by Adurane Clarke in …….


Due to the bulky nature of the raw material & its number of components with quite different applications, this is an indisputable fact.  In the view of the NZHIAI it is a positive aspect however, as it will by necessity reverse corporate centralisation of production which could easily revitalise ailing rural communities.

The Research & Development dollars are only just starting to be spent in this area with some promising results, portable decorticators which are able to separate out the various components that make up the useful parts of Industrial Hemp. Whole Hemp pulping technology has been developed, and plants are being setup in Canada & Victoria, Australia with the assistance of the Ukrainians, who developed the process.


This form of processing would, in the case of a fibre crop – involve splitting the dried (and retted) hemp stalks into their 3 main parts.

The 3 parts include 2 types (lengths) of Bast fibres from the inner and outer layers of the stalk and the hurd from the woody inner portion of the stem.  Crops allowed to fully develop would also under the right circumstances yield another marketable commodity, seed.

As Hemp has not been cultivated by western cultures on any real scale for the last 80 years, there are many areas of its production, which need to be developed.  There is a demand for suitable machinery to harvest fibre and seed crops, to ret and decorticate the stalks and to process them into higher value added products.

Local output from the processing phase will range from providing marketable commodities suitable as raw materials for other industries, through to maximum added value, when hemp based finished goods are produced and sold.

With minor changes to existing production technology some product can already be produced; others will require research and development to provide the expertise and knowledge needed to satisfy their production cycles.


New Zealand and its rural communities are desperately seeking sustainable alternative land uses. Hemp, because it provides enormous amounts of value added potential offers just such an alternative.

The Idea behind the Bio Regional Development of a hemp crop, involves local industry and the community working with local farmers to provide and manage suitable machinery and infrastructure close to the crop.

The size and extent of this processing and the associated returns will depend on the location, local support, and financial commitment available.

Suitable locations exist in New Zealand for this Bio Regional Development to occur.

This value added production done locally brings in the export dollars when the primary produce/commodity is sold