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Hemp (Cannabis sativa L.) is a member of the Cannabinaceae family, a small group of herbaceous plants.

Hemp most likely originated in Central Asia. It is one of the oldest cultivated plants, and has probably been cultivated in China for over 4500 years.

There are broadly three groups of Hemp varieties being cultivated today :

• Varieties primarily cultivated for their fibre, characterized by long stems and little branching.
• Varieties grown for seed from which hemp oil is extracted
• Varieties grown for medicinal or narcotic purposes. The resin, known variously as hashish, ganja or bhang, is obtained from the dried inflorescences, leaves and stems.

Until it's rediscovery in the late 1980s, the use of hemp for fibre production had declined sharply over the past decades, but hemp still occupied an important place amongst natural fibres as it is strong, durable and unaffected by water. The main uses of hemp fibre were in rope, sacking, carpet, nets and webbing. A hemp clothing industry was reborn in the West in 1988, and hemp is being used in increasing quantities in paper manufacturing. The cellulose content is about 70%.

Major hemp producing countries.

The Commonwealth of Independent States (former Soviet Union) is the world largest producer (300.000 hectares). The main production areas are in Ukraine, the Kursk and Orel regions of Russia, and near the Polish border.

Other important producing countries are the former Yugoslavia, Romania, Poland and Italy.

Canada, Britain, and Australia all resumed production in the 1990s. British production is mostly used as bedding for the Islands horses. The largest outlet for Canadian Fibre is automotive panels, while Canadia, China,Hungary, and Germany are processing hemp seed into a growing range of food products and cosmetics.

Harvesting the fibre

Smallholder plots are usually harvested by hand. The plants are cut at 2 to 3 cm above the soil and left on the ground to dry. Mechanical harvesting is now common, using specially adapted cutter-binders or simpler cutters. The cut hemp is laid in swathes to dry for up to four days. This is followed by retting, either water retting whereby the bundled hemp floats in water or dew retting whereby the hemp remains on the ground and is affected by the moisture in dew moisture, and by moulds and bacterial action.

A new future for hemp?

In the last decade hemp has been widely promoted as a crop for the future. This is in particular stimulated by new technologies which make hemp suitable for industrial paper manufacturing, use as a renewable energy source (biofuel), and the use of hemp derivatives as replacement for petrochemical products. The increased demand for health food has stimulated the trade in hempseed while hemp oil is increasingly being used in the manufacturing of bodycare products.

The THC debate

Hemp contains delta-9-tetrahydrocanabinol, which is the actual psychoactive ingredient found in hashish. THC is present in all hemp varieties to some extent. In varieties grown for medicinal or narcotic use, THC levels reach 20-30%. In hemp varieties for seed or fibre use, these levels are between 0.5% and 1.5%, which is far too low to obtain any narcotic effect and low enough to make THC extraction extremely difficult or uneconomic. On October 9th, 2001, the US Drug Enforcement Agency (DEA) ruled that even traces of THC in products intended for food use would be illegal as from February 6th, 2002. This would rule out the production or use of hempseed or hempseed oil in food use in the USA. The presence of THC in hemp varieties and the fear that THC could be extracted from industrial hemp for illegal purposes has hampered the development of hemp is many countries. Since the early 1990s, however, countries including Canada, Australia, the UK, and Germany have allowed experimental hemp plantings and some commercial scale production. Plant breeders are working on the development of new varieties which are low in THC.

Hemp resources

• Hemp Industries Association http://www.thehia.org
• Global Hemp Resources http://www.globalhemp.com
• North American Industrial Hemp council http://www.naihc.org

see Cannabis : History

To cultivate hemp

From the 1881 Household Cyclopedia

The soils most suited to the culture of this plant are those of the deep, black, putrid vegetable kind, that are low, and rather inclined to moisture, and those of the deep mellow, loamy, or sandy descriptions. The quantity of produce is generally much greater on the former than on the latter; but it is said to be greatly inferior in quality. It may, however, be grown with success on lands of a less rich and fertile kind by proper care and attention in their culture and preperation.

In order to render the grounds proper for the reception of the crop, they should be reduced into a fine mellow state of mould, and be perfectly cleared from weeds, by repeated ploughings. When it succeeds grain crops, the work is mostly accomplished by three ploughings, and as many harrowings: the first being given immediately after the preceding crop is removed, the second early in the spring, and the last, or seed earth, just before the seed is to be put in. In the last ploughing, well rotted manure, in the proportion of fifteen or twenty, or good compost, in the quantity of twenty-five or thirty-three horse-cart loads, should be turned into the land; as without this it is seldom that good crops can be produced. The surface of the ground being left perfectly flat, and as free from furrows as possible; as by these means the moisture is more effectually retained, and the growth of the plants more fully promoted.

It is of much importance in the cultivation of hemp crops that the seed be new, and of a good quality, which may in some measure be known by its feeling heavy in the hand, and being of a bright shining color.

The proportion of seed that is most commonly employed, is from two to three bushels, according to the quality of the land; but, as the crops are greatly injured by the plants standing too closely together, two bushels, or two bushels and a half may be a more advantageous quantity.

As the hemp plant is extremely tender in its early growth, care should be taken not to put the seed into the ground at so early a period, as that it may be liable to be injured by the effects of frost; nor to protract the sowing to so late a season as that the quality of the produce may be effected. The best season, on the drier sorts of land in the southern districts, is as soon as possible after the frosts are over in April; and, on the same descriptions of soil, in the more northern ones, towards the close of the same month or early in the ensuing one.

The most general method of putting crops of this sort into the soil is the broadcast, the seed being dispersed over the surface of the land in as even a manner as possible, and afterwards covered in by means of a very light harrowing. In many cases, however, especially when the crops are to stand for seed, the drill method in rows, at small distances, might be had recourse to with advantage; as, in this way, the early growth of the plants would be more effectually promoted, and the land be kept in a more clean and perfect state of mould, which are circumstances of importance in such crops. In whatever method the seed is put in, care must constantly be taken to keep the birds from it for some time afterwards.

This sort of crop is frequently cultivated on the same piece of ground for a great number of years, without any other kind intervening; but, in such cases, manure must be applied with almost every crop, in pretty large proportions, to prevent the exhaustion that must otherwise take place. It may be sown after most sorts of grain crops, especially where the land possesses sufficient fertility, and is in a proper state of tillage.

As hemp, from its tall growth and thick foliage, soon covers the surface of the land, and prevents the rising of weeds, little attention is necessary after the seed has been put into the ground, especially where the broadcast method of sowing is practised; but, when put in by the drill machine, a hoeing or two may be had recourse to with advantage in the early growth of the crop.

In the culture of this plant, it is particularly necessary that the same piece of land grows both male and female, or what is sometimes denominated simple hemp. The latter kind contains the seed.

When the grain is ripe (which is known by its becoming of a whitish-yellow color, and a few of the leaves beginning to drop from the stems); this happens commonly about thirteen or fourteen weeks from the period of its being sown, according as the season may be dry or wet (the first sort being mostly ripe some weeks before the latter), the next operation is that of taking it from the ground; which is effected by pulling it up by the roots, in small parcels at a time, by the hand, taking care to shake off the mould well from them before the handsful are laid down. In some districts, the whole crop is pulled together, without any distinction being made between the different kinds of hemp; while, in others, it is the practice to separate and pull them at different times, according to their ripeness. The latter is obviously the better practice; as by pulling a large proportion of the crop before it is in a proper state of maturity, the quantity of produce must not only be considerably lessened, but its quality greatly injured by being rendered less durable.

After being thus pulled, it is tied up in small parcels, or what are sometimes termed baits.

Where crops of this kind are intended for seeding, they should be suffered to stand till the seed becomes in a perfect state of maturity, which is easily known by the appearance of it on inspection. The stems are then pulled and bound up, as in the other case, the bundles being set up in the same manner as grain, until the seed becomes so dry and firm as to shed freely. It is then either immediately threshed out upon large cloths for the purpose in the field, or taken home to have the operation afterwards performed.

The hemp, as soon as pulled, is tied up in small bundles, frequently at both ends.

It is then conveyed to pits, or ponds of stagnant water, about six or eight feet in depth, such as have a clayey soil being in general preferred, and deposited in beds, according to their size, and depth, the small bundles being laid both in a straight direction and crosswise of each other, so as to bind perfectly together; the whole, being loaded with timber, or other materials, so as to keep the beds of hemp just below the surface of the water.

It is not usual to water more than four or five times in the same pit, till it has been filled with water. Where the ponds are not sufficiently large to contain the whole of the produce at once, it is the practice to pull the hemp only as it can be admitted into them, it being thought disadvantageous to leave the hemp upon the ground after being pulled. It is left in these pits four, five, or six days, or even more, according to the warmth of the season and the judgment of the operator, on his examining whether the hempy material readily separates from the reed or stem; and then taken up and conveyed to a pasture field which is clean and even, the bundles being loosened and spread out thinly, stem by stem, turning it every second or third day, especially in damp weather, to prevent its being injured by worms or other insects. It should remain in this situation for two, three, four, or more weeks, according to circumstances, and be then collected together when in a perfectly dry state, tied up into large bundles, and placed in some secure building until an opportunity is afforded for breaking it, in order to separate the hemp. By this means the process of grassing is not only shortened, but the more expensive ones of breaking, scutching, and bleaching the yarn, rendered less violent and troublesome.

After the hemp has been removed from the field it is in a state to be broken and swingled, operations that are mostly performed by common laborers, by means of machinery for the purpose, the produce being tied up in stones. The refuse collected in the latter process is denominated sheaves, and is in some districts employed for the purposes of fuel. After having undergone these different operations, it is ready for the purposes of the manufacturer.