Which crop has the maximum cultivation time

Hemp - cultivation and uses

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Niche cultures

Although a distinction is sometimes made between farm hemp and Indian hemp, botanically it is the same plant. Whether it is a classic agricultural culture or whether the plant falls under the Narcotics Act is determined by the culture and, above all, the varieties used. The decisive criterion is the THC content of a maximum of 1 percent in the dry matter. THC (Delta-9-Tetrahydrocannabiol) is the cannabinoid responsible for the psychotropic effect. Hemp contains around a hundred other cannabinoids, including CBD (cannabidiol), which is said to have a calming and anti-anxiety effect. It is also said to have an effect on numerous different systems in the body and is therefore of great therapeutic interest. The characteristic smell of hemp is caused by organic compounds called terpenes. These are said to have anti-inflammatory, antibacterial and antiviral effects. It is therefore not surprising that hemp is attracting a great deal of interest in medical circles.

Predestined for organic farming

Hemp (Latin: Cannabis sativa L.) is an annual dicotyledonous plant. Originally, hemp is a dioecious plant, which means that there are female and male plants. The male plants pollinate the female, which in turn form the seeds. If they are not fertilized, they will form seedless inflorescences. There are monoecious plants on the market (also called hermaphrodites) which have both female and male flowers. Hemp prefers medium-heavy soils with a good water supply, but does not tolerate waterlogging or compaction. The optimal pH of the soil is between 6 and 7.5.

Hemp has no special demands on the previous crop, but thanks to its taproot it has a good previous crop value. A three-year break from cultivation is recommended. Hemp is undemanding and robust. The most common disease is botrytis. So you can say that hemp is particularly suitable for organic cultivation. It can be grown for its fiber, its seeds or its female unfertilized inflorescences (with the high active ingredient content, in legal hemp is the CBD). The cultivation technique differs depending on the use of the end product (see table below). The illegal cultivation of hemp for narcotic purposes is not addressed in this article.

A quality fiber

In Switzerland, the hemp fiber industry is practically non-existent, in contrast to France and Germany (links at the end of the article). These countries have massively increased their efforts in this area in recent years. The hemp fiber is located in the stem, which is why a dense culture with as many long stems as possible is aimed for for this purpose. In order to remove the fiber (filaments), the cut stalks must remain in the field for two to three weeks and be turned regularly so that they are evenly exposed to the elements. During this roasting phase, the pectin, which holds the fibers together, is broken down by rain and sun. When the filament has detached itself from the lignified parts (shives), the crop can be pressed into bales and stored until it is spun. The shives used to be used as litter, today it is also used as a raw material for insulating material (building insulation).

The hemp fiber is of good quality and can be used in many ways (ropes, clothes, cord, paper, insulation, molded parts for the car industry, etc.).

A valuable oil

To produce hemp oil, the seeds are harvested and pressed. The oil from seeds does not contain any psychoactive ingredients, because it is not the essential oil or the extract from the resin of the plant. The seeds are harvested with combine harvesters, which are slightly modified and only harvest the uppermost parts of the plants. Threshing is demanding, the fibers can wrap around the threshing drum and clog the machine, which can result in lengthy cleaning work. It is also very difficult to chop the hemp straw for the same reason. At the moment there is only a very small oil production in Switzerland. The organic edible hemp oil or the hemp seeds are imported. After all, the Bern oil mill produces hemp oil from Swiss organic hemp seeds. (Internet shop price: CHF 155 per liter).

Under local conditions, 800 to 1000 kg of seeds per hectare can be expected in organic farming with an oil yield of 30 to 35 percent. The oil is rich in protein as well as omega 3 and omega 6 fatty acids. In addition to food, there are numerous other uses for hemp oil, for example as a fuel (it was even used by Rudolf Diesel in the development of his famous engine), in paints, varnishes, chalks and in the cosmetic field.

It is possible to use the stalks as raw material for further processing after the seeds have been threshed, but the quality is lower because the plant is harvested later for oil production than for fiber production.

Seedless flowers with a high CBD content

The production of legal flowers is much more demanding than the fiber and seed production, since only female plants are cultivated in the shape of a "Christmas tree". In order to achieve a large number of unfertilized inflorescences, only female plants must be planted. These are propagated vegetatively with cuttings from dioecious varieties. There must be no other hemp fields nearby, otherwise the pollen would fertilize the CBD plants and seeds would form. Since only one or two plants per square meter are targeted, this crop is very susceptible to snails, erosion and weeds. Weed control is essential and is done through careful chopping.
The CBD / THC content depends not only on the choice of variety, but also on the weather.

Organic hemp is particularly popular with users of legal cannabis because it does not contain any pesticide residues.

Since January 1, 2021, hemp is no longer subject to agricultural seed law in Switzerland. The Federal Office for Agriculture enables the production and marketing of seeds and planting material for the production of so-called “CBD hemp” in agriculture.

Hemp deregulated in seed law (Current section)

Cultivation dates for hemp

Frequencydioecious and single-domeddioecious and single-domed
Sowing timeMid-March to mid-AprilLate April to early May
Floor temperature at least5 ° C8 ° C
Seed ratearound 30 kg per hectare15 to 25 kg per hectare
Seed drill (type)GrainGrain
Sowing depthheavy soils: 3 to 4 cm
light floors: 6 cm
heavy soils: 3 to 4 cm
light floors: 6 cm
TKG16 to 19 grams12 to 17 grams
Row spacing10 to 20 cm10 to 20 cm
Weed controlnot necessary with good emergence of the hempnot necessary with good emergence of the hemp
fertilizationN: 100 kg
P2O5: 90 kg
K2O: 200 kg
Mg: 25 kg
N: 60 kg
P2O5: 50 kg
K2O: 100 kg
Mg: 15 kg
harvestAugust to September, during the flowering periodSeptember when the seeds start to fall out

A short version of this page was published in the magazine Bioaktuell 6 | 2017 on pages 10 and 11:
Article (219.2 KB)

Hemp profile, Agricultural Center Liebegg, Agridea data sheet on hemp, 2004

Additional information

Christian Hirschi and Matthias Klaiss, FiBL




Last update of this page: 09.02.2021

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