Hemp or Cannabis


What is Hemp?

Hemp, or Cannabis sativa L. Cannabaceae in its taxonomic form, is a plant believed to have originated in middle Asia. This species is not to be confused with other species that have adopted the term ‘hemp'. For examples, Manila hemp (abaca) is Musa textilis Née and sunn hemp is Crotolaria juncea L. (Small and Marcus 2002). Cannabis sativa is a multi-purpose plant that has been domesticated mainly for 3 purposes: for bast (phloem) fibre in the stem, seed (achene) production for nutrition and an intoxicating resin; tetrahydrocannibinol (THC). Although the same species has been used for all three purposes it is important to understand that it is not the same variety or ecotype of the plant that is used. Other names for Cannabis sativa are marijuana and cannabis but these are generally used for the variety that produces high contents of THC and not on varieties for fibre or seed that produce much lower percentages of THC. Scientists and the hemp industry are making great efforts to point out that “hemp is not marijuana”. Hemp typically contains below 0.3% THC that when ingested is not at sufficient levels for intoxication. While Cannabis sativa grown for intoxication can contain anywhere from 10% to 20% or even more which is sufficient to have a psychoactive affect. It is also important to understand the chemical that causes psychoactive effects, THC, secreted by trichome glands situated on the plant calyxes and leaves, not on or inside the seed. (West 1995).

The History of Hemp

The earliest recorded use of hemp goes back 12,000 years ago in Taiwan where strips of hemp fibres had been pressed into the wet clay of pots before it hardened to increase the overall strength (Li 1975). There is also evidence hemp was harvested for its hemp seed by the Chinese 8500 years ago (Schultes and Hofmann 1980). For most of its history, C. sativa was more valued as a food and fibre source and considerably less so as a drug source. C. sativa is the most commonly cited example of a “camp follower” (civilians who follow in the wake of armies or service their needs whilst encamped) showing that for millennia it has been considered one of the most valuable crops for utilisation. The domestication of the plant is believed to be due to pre-adapted to grow in the manured soils around man's early settlements (Schultes 1970). Hemp grown for fibre was initially introduced to western Asia and subsequently to Europe between 1000 and 2000 BC. Later, cultivation in Europe became widespread after 500 AD. In 1545 the crop was first introduced to Chile, South America and in 1606 was introduced to Port Royal, North America by travellers. From its first introduction into North America the hemp industry flourished in Kentucky, Illinois and Missouri between 1840 and 1860 because of the strong demand for sailcloth and cordage (Ehrensing 1998). Until the middle of the 19th century, hemp rivalled flax as the chief textile fibre of vegetable origin, and was described as “the king of fibre-bearing plants,—the standard by which all other fibres are measured” (Boyce 1900).

In the 1920s,the DuPont Companydeveloped and patented fuel additives such as tetraethyl lead and sulphites that are needed in the processes for manufacturing pulp paper. DuPont also developed numerous new synthetic products such as nylon, cellophane and other plastics. At the same time, other companies were developing synthetic products from renewable biomass sources such as hemp. For example, in the 1930s, Ford Motor Company engineers successfully conducted a pilot plant where they produced alcohol, tar, charcoal and other stock chemicals from hemp. Henry ford even made a car out of a mixture of hemp and soybean plastic that was “10 times stronger than steel” and ran it on ethanol made from hemp (Marquis and Samuel 1923).

Picture 2: Henry Ford striking his car made of hemp and soybean plastic with an axe, leaving only a scratch. The car was also run on biofuel. Taken from: The collections of the Henry Ford Museum.

In the 1930's a campaign was launched to smear the name of hemp, funded by petroleum and textile companies by linking it to its psychoactive variety (Herer 2006). This sparked the anti cannabis campaign where various propaganda film such as the popular “Reefer Madness” (1938) and posters were made with such slogans as “Weed with roots in hell”, “Weird Orgies, Wild Parties” and “Cannabis; the devils harvest” which effects can still be seen today as the majority of people consider hemp and cannabis as the same. Hemp paper, which uses less chemicals, less energy and less space than what is needed to produce tree paper, threatened companies' monopolies on the necessary chemicals for manufacturing paper from trees. Similarly hemp fibre would compete with Nylon, a synthetic fibre, that was patented in 1938, the year hemp was made illegal (Herer 2006). Consequently, the Marihuana Tax Act applied in 1938 essentially ended hemp production in the United States. Similarly in 1938 the cultivation of Cannabis became illegal in Canada under the Opium and Narcotics Act.

During the last decade in Canada, some European countries and China, hemp has been reconsidered as a valuable industrial crop for both food and fibre. Because of this, in these countries, hempseed products have become available to the general public. Though companies like Braham and Murray that makes hempseed oil and other hemp seed products are available in major supermarkets in the U.K., the potential for hempseed to be a highly valuable nutrition source has not yet been realised by mass markets. Today throughout Asia, Russia and Eastern Europe its nutritional properties have long been recognized and valued as a food source for humans and domesticated animals. In China, roasted hempseed is still sold as snacks by street vendors. In Russia, hemp oil has been used as a substitute for more expensive and less healthy sources of dietary fat, such as butter and hydrogenated margarines (Callaway 2002). It is only in recent years that modern science has begun to discover this ancient knowledge of hempseed through its own methodologies (Kriese et al. 2004).

Why Hemp?

Seed nutrition content

Whole seed (%)

Seed meal (pressed) (%)

Soybean (%)

Flax seed (%)


























Energy (kJ/100 g)





Total dietary fiber (%)





Digestable fiber





Non-digestable fiber





Table 1: Typical nutritional content (%) of hempseed unpressed (whole seed), pressed (seed meal), soybean and flax seed. (Callaway 2004)

Hemp seed is considered as “The most nutritionally complete food source in the world” (Osborne 1992). Raw, un-pressed hempseed typically contains over 35% oil, 25% protein and 28% carbohydrate as well as considerable amounts of dietary fibre, vitamins and minerals. Although soybean and flax seed have shown to also have such great levels of nutrition it is outcompeted when compared to other nutritional values. Hempseed oil has over 80% polyunsaturated fatty acids (PUFAs), and contains all 8 essential amino acids (EAA), mostly in levels superior to that of soy protein and flax seed with exceptionally high levels of arginine.

Hemp seed not only has a rich source of the essential fatty acids linoleic acid (18:2 omega-6 (n6)) and alpha-linolenic acid (18:3 omega-3 (n3)) but it is the ratio of between has a ratio of 2:1 and 3:1 which is considered to be optimal for human (soybean has 7:1, flaxseed 0.2:1). Hempseed also contains the biological metabolites of omega 3 (gamma-linolenic acid) and omega 6 (stearidonic acid) making it easily digestible in which flax and soybean lack.

Hempseed oil

The fatty acids in hemp seed are found in the hemp oil which can be collected from pressed hemp seed. EFAs are fatty acids that must be obtained through the diet as they cannot be made by humans and so supplements with oils that contain high levels of EFAs and other polyunsaturated fatty acids (PUFAs) are vital to enhance human health and development (Simopoulos 1991). PUFAs are also very important in the health of human beings and animals. PUFAs incorporate themselves in the phospholipid bilayers of cell membranes and crucial for maintaining essential characteristics of cell membrane fluidity, especially in the construction of neuronal membranes within the central nervous system.


Palmitic acid

Stearic acid

Oleic acid

Linoleic acid

AL acid




n6/n3 ratio

Oil hempseed










Fibre (vr.) hempseed










Black currant










Flax (linseed)










Evening primrose




















Wheat germ










Rape seed


















































Table 2: Typical fatty acid content profiles (%) of hemp and other seed oils. (Callaway 2004)

The fatty acid profile in low-density lipoproteins (LDL) can be positively influenced by PUFAs and their biological metabolites when compared to saturated fats in the diet, which are strongly associated with coronary heart disease (Callow et al., 2002). This means a diet that has high levels of PUFAs can lower blood pressure and arterial levels of LDL-cholesterol and in humans.

Metabolism of dietary fatty acids

The optimal ratio of n6/n3 reflects the ratio found in the traditional Japanese and Mediterranean diets, where the levels coronary heart disease has been historically low. Excessive levels of fatty acids can have a negative effect. For example, an excess of dietary alpha-linolenic acid (omega- 3) can disturb the metabolic balance by leaving a net deficit of omega-6 metabolites. The ratio of EFAs in hempseed allows the enzymatic step with delta-6-desaturase to be efficiently bypassed (Okuyama et al., 1997). Rapeseed oil (Brassica napus), also contains the optimal ratio of n6/n3 ratio of about 2:1 but lacks any of the vitamins and mineral values that hempseed has.

Hempseed protein and other nutrients





Soy bean



Egg white

Whey powder

Amino acid










Table 3: Typical protein content of various foodstuffs. (Calloway 2004)

The two main proteins in hempseed are edestin (a legumin) and albumin both globular proteins (biologically active) that are high-quality storage proteins rich in amino acids are easily digested by the body (Calloway 2004). A comparison of protein amino acid profiles from various vegetarian protein sources shows that hempseed protein is comparable to these other high quality proteins. Only soybean has levels of amino acids mostly higher than hempseed. It may be surprising to know hempseed is comparable to meat in terms of protein content, which considered the richest source of protein; chicken has 31%, fish and beef both have 29% protein (average values). Although meat generally contains higher levels of amino acids, it lacks many of the other valuable nutritional properties hempseed has. Hempseed protein has good amounts of the sulfur-containing amino acids

Hempseed (unpressed/


Soybean (unpressed/


Flaxseed (unpressed/


Vitamin E




Thiamine (B1)




Riboflavin (B2)




Phosphorous (P)




Potassium (K)




Magnesium (Mg)




Calcium (Ca)




Iron (Fe)




Sodium (Na)




Manganese (Mn)




Zinc (Zn)




Copper (Cu)




methionine and cystine, in addition to very high levels of arginine and glutamic acid; higher than that of any foodstuff listed in table 2. Furthermore when soybean and flaxseed are compared to hempseed they fall short when vitamins and minerals are considered as they both only have 3 out of the 12 vlaues greater than that of hempseed (Table 3).

Table 3: Typical nutritional values (mg/100g) for vitamins and minerals. Information from www.nutritiondata.com. Accessed: 17/02/10

Animal feeding trials

A study of trials using chickens have shown that feeding them with hempseed provides an excellent source of nutrition for egg laying hens. It was shown that the omega fatty acid profile in egg was favourably influenced after feeding hempseed meal compared to conventional chicken feed (Silversides et al. 2002). Another study on cows and sheep showed hempseed to be an excellent source of ruminant protein (Mustafa et al. 1999) as well as unpublished results from recently completed trials in Finland have demonstrated hempseed meal to be at least as good as soy meal in farmed fish feed.

Taste wise, hempseeds have an attractive nutty taste and is incorporated in many foodstuffs, often mimicking familiar foods. Those sold in North America include nutritional (granola-type) or snack bars, “nut butters” and other spreads, bread, pretzels, cookies, yogurts, pancakes, porridge, fruit crumble, ice cream, pasta, burgers, pizza, salad dressings, mayonnaise, “cheese” and various beverages including beer and milk which when compared to other non-dairy milk is similar and in some cases better nutritionally; e.g. hemp milk is a better source of calcium than cow's milk. Hemp food products currently have a niche market, based particularly on natural food and specialty food outlets.

Medicinal and health properties

Non-intoxicating varieties of Cannabis have not been studied extensively for their nutritional potential in recent years which probably explains why hempseed has not been fully utilized to any great extent during the 20th century by the industrial and food markets. Recent clinical trials have identified hempseed oil as a functional food, and animal feeding studies demonstrate the long-standing utility of hempseed as an important food resource.

Hempseed has been used to treat various disorders for thousands of years in traditional oriental medicine (Bensky et al. 2003) in addition THC has showing positive results in recent medical trials in alleviating various ailments including stimulation of hunger in chemotherapy and AIDS patients, amelioration of nausea and vomiting, treating glaucoma, as well as general analgesic effects.

The recent availability and use of hempseed oil in Europe and North America has created unscientific beliefs that hempseed can improve health in the form of alleviating acute and chronic conditions; e.g. from the rapid healing of simple cuts and burns to influenza, various skin problems, other allergic symptoms and inflammatory diseases. Most, if not all, of these claims are most likely due to the fatty acid profile of hempseed oil (Deferne & Pate, 1996; Kriese et al., 2004) and its direct impact on the subsequent metabolism of EFAs including eicosanoids (Table 2). Eicosanoids have been used to alleviate chronic disease states of the human immune system (Darshan & Rudolph 2000).

Recent evidence has described how dietary fatty acids in hempseed can be used in the treatment of tuberculosis without the use of antibiotics (Russell 2003). A recent clinical study by Grigoriev (2002) showed that applying hempseed oil to heal mucosal skin wounds after eye, nose and throat surgery has already demonstrated very positive results. This finding also agrees with numerous other clinical studies that have shown the usefulness of EFAs and other PUFAs in healing and immune response (Simopoulos 2002). In a randomized, crossover study statistically significant improvements were seen in both skin quality and in plasma fatty acid profiles when hempseed oil was used on patients that suffered from eczma within eight weeks after the ingestion of hempseed oil at 30 ml day (Callaway et al. 2004).

THC and other Cannabinoids

Most scientific research on Cannabis over the last 40 years has focused on the putative toxicity of THC and, to a lesser extent, other cannabinoids (a group of terpenophenolic compounds present in Cannabis in which THC is one of and occurs naturally in the nervous and immune systems of mammals). Surprisingly, this research has resulted in the discovery of new medicines (Mechoulam et al. 2002). I addition, THC and other cannabinoids are potent lipophilic antioxidants, which could explain some of the therapeutic potential associated with Cannabis (Hampson et al. 2000).

Other uses

Not only is hemp a highly nutritional food source it has exceptional fibres for building material, composite materials, paper, fabric, cordage and animal bedding.

Hemp fibre is one of the strongest and longest naturally occurring fibres, superior to cotton and flax (Karus and Leson 1996). It is commonly called bast, which refers to the fibres that grow on the outside of the woody interior of the plant's stalk. Hemp fibres can be between approximately 0.91m (3ft) and 4.6m (15ft) long, running the length of the plant.

Hemp produces 10% more fibre than cotton and 10% more fibre than flax when grown on the same land (small and Marcus 2002). Dispite this the use of hemp for fibre production has declined sharply over the last two centuries, but before the industrial revolution, hemp was a popular fibre because of its strength and ability to grow quickly (3-4 months to reach maturity). It was often used to make sail canvas, the word canvas even comes from the word cannabis (etymonline.com).

Biofuels such as biodiesel and alcohol fuel can be made from the oils in hemp seeds and stalks, and the fermentation of the plant as a whole, respectively.

Hemp can also be used to purify water and soil by removing impurities as well as having a dual purpose of weed control due to the nature of the plant by means of choking out weeds by dense populations. Using hemp this way can help farmers avoid the use of herbicides, to help gain organic certification and to gain the benefits of crop rotation per se.

No other plant on this planet to my knowledge has so many benefits.

Why Africa?

Africa is the world's second most-populous and second-largest continent, after Asia, with a population of 1, 033,043 (esa.un.org 2008). It is deemed the poorest and most undernourished continent in the world.

Studies have shown agriculture to be the most effective driver of growth in the world's poorest countries (Juma 2008). Increasing agricultural productivity is vital for improving food security, reducing rural poverty and stimulating broad-based economic growth. These idealistic advances are not easy tasks to tackle. Any plans for improving agriculture depends on improving the economic, technical, legal and trade conditions under which small scale farmers and agribusinesses must operate.

The flow of adequate food supplies to meet the rapidly increasing population's rising demand is furthermore threatened by climate change and land degradation due to soil erosion. According to the United Nations, the present world population is at about 6.3 billion with a predicted increase to 8 billion in 2025 due to the average annual growth rate of 1.3 (United Nations Population Reference Bureau, 2004). The majority of the world's population lives in the emerging and least developed countries. Increasing food demands are fuelled by the rising number of people as well as improving diet requirements. Increasing global food production is the biggest challenge in this regard particularly in Africa in the next 15 years. Though total land area in the world is 13,390Mha, only 1500 Mha (11%) of this is used for agriculture. The potentially cultivable land is estimated to be around 3000Mha but the main problem of this uncultivated land is it is not as fertile and therefore not as productive as current arable land. The land which can be brought into production to double production can be achieved only by suitable strategies of soil and water conservation and management and by improving soil fertility along with improving existing or introducing new crops. Currently, the total irrigated area in the world is about 260Mha or about 17% of the cultivated area, of which two-thirds is in the developing countries. These lands are mainly marginal, spread over poorly productive environments and with weak production capabilities and therefore limiting the ability for increasing production. Using existing as well as further research is key to distinguishing the problems and abilities of using a new crop for production. Emphasis on creating engineered techniques and conservation measure for rain fed agriculture is just as, if not more important.

Despite the help of various organisations the problem of hunger in Africa is widespread and getting worse. The numbers are staggering. It is estimated that one in three people in Africa are currently undernourished and that a third of all the worlds undernourished people reside in sub-Saharan Africa (Rosen and Shapouri 2001). According to a USDA study, in 2010 Africa may account for nearly two-thirds of the undernourished people in the world. Organisations such as USAID aim to rapidly and sustainably increase agricultural growth and rural incomes in sub-Saharan Africa. To reach this objective, USAID will invest in training and technical assistance to promote science and technology in key agricultural areas. This can expand markets and trade opportunities, strengthen producer, protect the vulnerable and manage risk, processor and trade organizations, ensure environmental sustainability and further institutional capacity building. USAID is currently being implemented through three sub-regional areas in Africa (East, West and South) as well as individual country programs in Ghana, Kenya, Mali, Mozambique, Nigeria, South Africa, Uganda, and Zambia.

Other companies such as Strategic Analysis and Knowledge Support System can improve policy making and planning as well as program monitoring and evaluation. It can give decision-makers, such as members of parliament, information based on sound empirical data and reliable analysis. Data needs by collected, compiled and analysed by appropriate tools as well as contributions to national monitoring and evaluation systems by supplying timely information to national institutions and international organisations.

According to the World Bank (1997) in sub-Saharan Africa over 60% of the population depends on rain-based rural economics which generates about 30–40% of the regions' GDP. Rain-fed agriculture is practiced on approximately 95% of agricultural land, with only 5% under irrigation (Rockstrom et al., 2002). Many researchers suggest that the low productivity in rain-fed agriculture is more due to management at sub-optimal performance than to low physical potential. For example, it is Bennie et al., 1994 Bennie, A.T.P., Hofman J., Coetzee, M.J., Very, H.S., 1994. Storage and utilization of rainwater in soils for stabilizing previous termcropnext term production in semi-arid areas. (Afrikaans) WRC Report No. 227/1/94. Water Research Commission, Pretoria, South previous termAfrica.next term reported that in many arid and semi-arid areas between 60% and 85% of the rainfall evaporates from the soil surface before making any contribution to production (Bennie et al. 1994).


Significantly increasing the health of the people of Africa through food quality and amount cannot be achieved by just one method. It has to be brought about by a number of methods:

1) Improving food quality by introducing a crop capable of producing adequate amounts of highly nutritional food in the environment it's subjected to,

2) Increasing food production by improving soil quality and agricultural practices,

3) Improving water storage, especially for dry season,

4) Improving irrigation techniques to maximise the efficiency of water use.

Introducing a new crop

For Example, South Africa's largest crop industry is mainly maize and wheat under rain-fed conditions. Since deregulation in agriculture and the termination of subsidies from the mid 1990's significant changes have taken place. The total area used for grain has decreased from 25% to 15% (Theron 2002) due to lower prices caused by import value equality and free market coupled with the absence of state subsidies making production more risky. Consequently, grain planting has decreased significantly on low yield potential land as well as on high yield potential land in remote areas.

There are examples of successful new crop industries established in South Africa. One is the canola industry in the Western Cape Province. Since the 1990s it has grown from virtually no industry since from zero production to a production area of 30,000 ha currently, with two processing plants in now operational (Theron 2002).

The reason for the introduction of this crop came about through a contracted Canadian Researcher. He was instructed to research on alternative crops for the wheat industry in the Western Cape Province. Canola proved to be the best alternative of crops tested, though hemp was not tested due to prohibition. It was first considered for a domestic niche market of cooking oil. Farmers started to produce in small quantities and the crop was pressed for oil. Initial pressing was at an original oil seed factory but production increased so much that this plant could not handle the supply. Consequently, two plants were erected by agricultural co-operatives. This was only doe after the capital investment was justified by regional levels of canola production. Current research is continuing to decrease the potential productivity of the crop, for example reducing uneven germination causes some plant's growth to be reduced due to larger competing plants (Willenburg et al. 2004).

Rain, irrigation and storage

65% of terrestrial rain is considered ‘green water' (water that is stored in the soil and is available to plants). Water may infiltrate and be held in the soil or drain to into groundwater and stream base flow. Runoff, groundwater and stream base flow is termed blue water (Ringersma et al., 2003). Nearly all the world's attention, research and development efforts have gone into blue water. Although irrigation plays one of the most important roles in food production, the possibilities of further development and expansion seems to be limited since water resources of sufficient quality become scarce or too expensive to use. Since an increasing population requires increased food production, more efficient use of rain in rain-fed agriculture deserves our increased attention.

Rwanda (Example)

Rwanda's population growth has put tremendous pressure on the limited natural resources such as water, land and forests which do not meet the high demand of the population needs. This has led to misuse and over-exploitation of natural resources which in turn leads to environmental degradation. Rwanda is an agriculture based country where crop production is carried out under rain fed situation with wide range of climates. 95% of agricultural land in Rwanda is purely rain fed where as only 5% is under irrigation. 52% of the total land area in Rwanda is available for cultivation showing that there is great potential for plentiful crop production if limiting factors were removed or reduced. Almost 90% of the potential soils for agricultural production are located in hillsides with very steep slopes (Delepierre and Prefol, 1973). Field experiments by Kanana et al. (2008) were conducted by using maize with in-situ soil moisture conservation techniques in bench terraces and field from June 2007 to October 2007 by involving three land management practices; ridges and furrows, compartmental bunding and control (no treatment). When rainfall and crop water demand is compared it is obvious that it is crucial to provide supplemental irrigation and in-situ moisture conservation for a successful crop. Kanana et al. (2008) found bench terrace increased the average soil moisture content in 90cm soil depth by more than 50 per cent than that of unterraced land. Within the bench terraced field compartmental bunding increased soil moisture by 18.2% higher than plain bed (control) and ridges & furrows increased by 27.8%. This proves in situ moisture conservation measures are more successful at retaining water than plain. Higher moisture content in these two techniques is due to the water barrier that collects rainwater. But in all the three techniques, actual soil water during the entire cropping period remains below field capacity posing soil moisture stress to the plants. The soil water was reduced to 60% and above from the beggining of the cropping period. This caused the yield of the maize to be very low showing the need for supplementary irrigation. The plain bed exhibited the lowest degree of fluctuation of deficit water showing it was poorly influenced by rain fall.

Capturing rainwater where it falls and storing it in the root zone is perhaps the most cost-effective means of increasing water availability, for plants and people. For example, in parts of semi arid Tanzania, converting from plowing to sub-soiling led to doubling of yields in good years (Jonsson, 1996). In Australia, Williams et al (1983) estimated that when the profile of a soil had a moisture store depth of less than 100 mm it had a less than 30% probability of meeting the moisture requirement of a sorghum crop, and even 200 mm had only a 70% probability of supplying sufficient moisture. Furthermore Tenge et al (2005) found in situations where moisture is the limiting factor, crop yields are expected to be higher on bench terraces. Comparing rainfall with crop requirements will explain the most suitable moisture conservation. Narayana and Babu 1985 give three conditions:

1) Where rainfall supply is less than crop requirements, run-off onto the arable land, fallowing for water conservation, the use of drought tolerant crops and suitable management practices will need to be applied.

2) Where precipitation is equal to crop requirements, local conservation of rainfall, maximizing storage within the soil profile and storing excess run-off will ensure supply meats demand.

3) Where rainfall amount exceeds crop requirements measures to minimise rainfall erosion, drain surplus run-off and store it for subsequent use will need to be in place.

The most common problem of lack water supply to crops, animals and humans is due to water storage, not just in Rwanda but in most parts of the world. It is surprising to find that on average the annual rainfall of Kenya, for example, is 193cm near Lake Victoria and 102cm near the coast and highland areas where as in England the average annual rainfall is 92.9cm. It is the high temperatures in Kenya that causes high evapotranspiration and evaporation rates, and therefore droughts as well as poor water storage management, not the overall water supply that causes low productivity.

It is impossible to store water without lining harvesting structures which is usually expensive. Although in situ soil moisture conservation would be the cheapest way to try and conserve water it is not necessarily the most cost effect and as shown previously not always sufficient. A method has to be decided based on storage capacity of soil and its seasonal variation. Rain water interception, its distribution and contribution to different components of water balancing process needs to be understood.

Irrigation in African Highlands

When farmers in semi-arid Africa are asked what the biggest cause of decreased production is, drought always ranks higher than erosion or land degradation (Stroosnijder and Van Rheenen, 2001).

During the last decade, the Southern and Eastern Africa Rainwater Network (SEARNET) with support from the Regional Land Management Unit (RELMA), a SIDA funded unit based in Nairobi Kenya, has been promoting rainwater harvesting in Eastern and Southern Africa. SEARNET has nine African member countries. Together these organisations came up with the following points:

• Water storage falls below 1700m3/capita/year (international minimum) in areas where access to land availability of water in the region due to inadequate water harvesting infrastructure

• Extremely low agricultural production (less than 1tonne/ha) due to dry spells and drought which has been worsened by climate change.

• Poor management of rainwater which leads to erosion, ecosystems, flooding and pollution.

Most national governments in Eastern and Southern Africa (ESA) only allocate money for conventional water supply systems such as boreholes and dams as a means of water for agricultural, industrial and domestic use. However, such systems are often centralized, expensive and benefit mainly those in urban areas. Improving water management is crucial to help developing countries combat poverty and hunger. Various programmes, for example the Rwanda vision 2020 Intensification and Development of Sustainable Production Systems Programme, have been introduced to encourage the correct allocation of money to water sustainability.

Hemp Agronomy

To study the influence of nitrogen fertilisation and seed density in hemp (Cannabis sativa L.) field trials were carried out in Switzerland and South Germany. A high seed density (30-60 kg/ha) and nitrogen fertilisation did increase stem and bast yields. Nitrogen also increased seed yield, plant height but also lodging. Seed yield was higher at lower seed density (10 kg/ ha). At this plant density no sufficient cover against weeds was observed. Low seed density and also high nitrogen supply may increase difficulties for mechanical grain harvest.
We recommend for grain hemp a seed density of at least 30 kg/ha and a maximum nitrogen fertilisation of 50 to 85 kg N/ha. For fibre hemp the maximum nitrogen fertilisation should be 85 to 120 kg N/ha (Mediavilla 1998).

1. Plant Description

Hemp (Cannabis sativa L.) is an annual herbaceous plant with a slender stem, ranging in height from 4 to 15 feet and a diameter from 1/4" to 3/4". The innermost layer is the pith, surrounded by woody material known as hurds. Outside of this layer is the growing tissue which develops into hurds on the inside and into the bast fibers on the outside. The stem is more or less branched, depending on the crop density. When sown thickly the stems do not branch. The leaves are of a palmate type and each leaf has 7 to 11 leaflets, with serrated edges. The strong tap-root penetrates deep into the soil. However, if the soil conditions are unfavorable, the main root remains short, while lateral roots become more developed.

2. Soil and Soil Preparation


Industrial hemp can be grown on a wide variety of soil types. Hemp prefers a sufficiently deep, well-aerated soil with a pH pf 6 or greater, along with good moisture and nutrient holding capacity. Poorly drained soils, however, are not recommended as excess water after heavy rains can result in damage to the hemp crop. Hemp is extremely sensitive to flooding and soil compaction

Soil Preparation

A fine, firm seedbed is required for fast, uniform germination of hemp seed. Conventional seedbed preparation and drilling are probably ideal. The seedlings will not emerge uniformly if the seed is placed to a depth greater than 2 inches. "No-till systems" can also be used with good results, but may be more vulnerable to erratic emergence depending on the growing season.

3. Nutrition

To achieve an optimum hempyield, 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 vegetative 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./acre (120 to 150 kg./ha) nitrogen, 45 to 70 lbs./acre (50 to 80 kg/ha) phosphate and 52 to 70 lbs./acre (60 to 80 kg/ha) potash.

4. Growing Conditions

Hemp prefers a mild climate, humid atmosphere, and a rainfall of at least 25-30 inches per year. Good soil moisture is required for seed germination and until the young plants are well established.

5. Weed Control

Industrial hemp is an extremely efficient weed suppressor. No chemicals are needed for growing this crop. Industrial hemp is a low maintenance crop. There are no registered chemicals for weed control in hemp. A normal stand of 200 to 300 plants per square meter shades out the weeds, leaving the fields weed-free at harvest for the next crop.

Notice the canopy effect created by the dense planting. When properly planted and cultivated, weed control is a non issue.

6. Time of Seeding

The best time to seed hemp should be dictated by the weather and soil conditions, rather than the date on the calendar. Hemp can be seeded as early as two weeks prior to corn provided that soil conditions are optimum. However, seeding should not begin until soil temperatures have reached a minimum of 41 - 46 deg.F. (6 - 8 deg C.). Hemp seed germinates within 24 to 48 hours, and emerges in 5 to 7 days with good moisture and warm temperature.

7. Plant Population

High yields of high quality fiber can be achieved with proper plant density. Seeding rates of 250 to 400 viable seeds per square meter are probably ideal, depending on soil type, soil fertility and cultivars. The seed or grain production will require lower seeding rates.

This stand is ready to harvest. Note the uniformly dense population.

8. Breeding Characteristics

Generally, hemp is a dioecious plant ( a plant having the stamens [male] and the pistils [female] borne by separate plants of the same species ). However, there are three classifications of varieties:

* monoecious varieties - when male and female flowers develop on the same plant;

* dioecious varieties - with distinct male and female plants;

* female predominant varieties, obtained by pollinating dioecious females with monoecious pollen.

9. Cultivar Types

There are two types of industrial hemp based on their use.

* fiber cultivars - with long stalks and little branching; (shown to the left)

* seed cultivars - with shorter stalks, larger seed heads and may have numerous branches (seed contains 30 - 35% oil). (shown to the right)

10. Rotation

Hemp can be grown on the same ground for several years in succession but rotation with other crops is desirable. Hemp responds well to most preceding crops. It is also possible that introduction of hemp in a crop rotation might improve the soil health. In 1996, Kenex Ltd. of Canada observed that hemp may significantly reduce the population of soybean cyst nematodes.

11. Harvest

Harvesting of hemp for high quality fiber occurs as the last pollen is shed. Harvesting for seed occurs 4 to 6 weeks later, when 60% of the seed has ripened. Fiber hemp is normally ready to harvest in 70 to 90 days after seeding. The end use of the product may significantly impact on the harvesting method.

Kennex Ltd. of Canada, is developing a harvesting system that will be compatible with the new processing technology. For fiber production, the crop will be cut, dew retted in the field, baled and stored or processed.

12. Retting

The bast fibers are obtained by retting - a microbial decay of pectin, the substance that glues the fiber to the woody core of the hemp stem together. Retting is carried out in the field and depending on the weather, takes 12 to 18 days to complete. During retting, the stems need to be turned one or two times in order to allow for even retting, since the stems close to the ground will remain green while the top ones are retted and turn brown. Retting is complete when the fibers turn a golden color and separate easily from the mass to finer fibers.

13. Yield

Based on yield data from 1995 and 1996 along with preliminary estimates for 1997, yield expectations are between 3 to 5 tons of baled hemp stalks per acre on well drained loamy soils in South Western Ontario.

14. Storage

For storage, the moisture content of hemp stalks should not exceed 15%. The bales can be stored for a long time in dry places which could include storage sheds, barns or other covered storage.

The information provided in this fact sheet is based on research sponsored by Kenex Ltd., RR#1, Pain Court, Ontario, Canada, N0P 1Z0. The information reflects research data gathered from the test plots at Ridgetown College and the Kenex pre-commercial field trials at Pain Court. Information is based on research from 1995 thru 1997 at these two facilities.

Hemp Field Notes from the Great AgVenture now online

Jack Moes, in his role as an authorised crop sampler, likely saw the most hemp fields of any person in North America this year. All in all, he inspected close 100 fields in Saskatchewan and Manitoba, including commercial fields and pedigreed seed fields and plots.

Fields ranged from those choked in wild oats to those with heartier dispositions. His observations include:

* Hemp does not like an overly packed seedbed

* Hemp does not like "wet feet"

* Hemp does not like drought

* Hemp likes fertile, well-structured soil

* Excess fertility is a possibility

* Appropriate fertility is a challenge for organic growers

* Fin 314 has its pros and its cons

* Hemp is sensitive to herbicide residues in soil

* Watch out for Bertha armyworm in 2001

* Sclerotinia can be a significant problem

* (Too many) male plants in monoecious varieties such as USO 14, USO 31 & Zolotonosha 11

* Harvest timing: direct combine at 20-25% seed moisture for best results for most varieties

For full details check out http://www3.mb.sympatico.ca/~jmoes/hemp2000rpt.html

The Benefits of Irrigation in FIN-314 Hempseed Cultivation Irrigation increases seed yields by 25%

In 1998, faced with the prospect of having to multiply a small lot of FIN-314 planting seed to supply a growing market, we (at Gen-X) were looking for various ways to increase crop yields. We identified irrigation as a possible solution. To test our hypothesis, a crop of FIN-314 oilseed hemp was planted under a pivot irrigation system in 1999. This crop ended up yielding just over 2000 lbs./acre of uncleaned seed (previously reported in the HCFR), possibly a record for commercial production in Canada. This gratifying result led us to explore the benefits of irrigation further in 2000, both in plot research and commercial production. The results are extremely encouraging.

In co-operation with the Sask. Hemp Association and the Canada-Saskatchewan Irrigation and Diversification center, in Outlook, a replicated plot trial was planted in late May, 2000, to compare the response to irrigation of eight common varieties of hemp. All varieties grew extremely well, both in the irrigated and non-irrigated plots, due to good weather conditions, proper fertilisation and good seeding techniques.

FIN-314 was the shortest and earliest variety, maturing at five feet (non-irrigated) to six feet (irrigated). Some of the taller varieties surpassed 12 ft, with a significant increase in height and biomass due to irrigation. Unfortunately, complete seed yield results could not be obtained, simply because it proved impossible to harvest any varieties except for FIN-314, the others being too late and too green, and too much for a plot combine to handle. However, the FIN-314 plots were harvested without too much difficulty.

To sum up, non-irrigated FIN-314 yielded an average of 1398 kg/Ha of clean seed (1255 lbs./ac), and a maximum of 1671 kg/Ha (1501 lbs./ac). In the irrigated plots, FIN-314 yielded an average of 1742 kg/Ha (1565 lbs./ac), and a maximum of 2364 kg/Ha (2123 lbs./ac). This corresponds to an average increase in seed yields by 25% due to irrigation.

In commercial production, three FIN-314 crops were planted under irrigation systems in 2000, for a total area of 185 acres. These crops were among the best crops harvested this year, all yielding above 1000 lbs./acre (the average yield for conventional FIN-314 growers on the prairies in 2000). David Wiens, of Lomond, southern Alberta (near Lethbridge), achieved yields of 46 bushels (uncleaned) to the acre on 40 acres (approximately 1600 lbs. of clean seed per acre).

It is evident that irrigation can increase the competitiveness and vigour of hemp crops, especially in areas of the prairies where dry spells and scarce moisture are an issue. In all cases, irrigation was applied only on a need basis; only one or two passes (waterings) during drier periods may be needed in a season to significantly increase yields - timing is everything in cost-effective irrigation.

Irrigation may result in higher GLA levels

Samples of "irrigated seed" were analysed for their essential fatty acid (EFA) profiles, with interesting results. The samples from irrigated fields were significantly higher in GLA content (3.8 - 4.3% GLA) than non-irrigated samples (3.2%). These are preliminary results, which may warrant further investigation, but it seems safe to hypothesise that irrigation may encourage better seed formation and maturity, thereby increasing GLA levels. Irrigation can thus be indirectly linked to higher GLA levels, higher yields in FIN-314 hemp, and possibly, higher total levels of polyunsaturated fatty acids.


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