For reference: Eden Foundation, Sweden (1996:1)
IntroductionFarmers living in arid lands have two goals in mind, namely to produce a reliable harvest from their fields and to do this economically by conserving water and nutrients, etc. Eden Foundation saw these goals being compromised by the environmental degradation taking place in the Sahel and other hot arid areas.
Problems associated with the monoculture of annualsLand degradation can clearly be seen in the district where Eden's field station is situated, which is located in Niger, 14°51'N 8°52'E (130km north of Zinder) in a 200mm rainfall area. Here land is cleared to grow annual crops (millet). Perennials are considered to be in the way and are therefore cut down or uprooted. As a consequence there are few perennials left for grazing or firewood collection. After harvest, farmers burn what is left of the millet plants leaving the fields exposed to severe wind erosion. This depletes the top soil of nutrients, and sand and dust storms regularly occur. Water run-off also takes place when the terrain becomes denuded of perennials.
Deep wells and boreholes are sunk in hot arid areas for irrigating annuals such as wheat and tomatoes. Water tables have lowered considerably as a consequence. In some parts of Syria the water level is falling at a rate of two metres per year (Vesilind 1993). In Texas the water level has lowered thirty metres between the 1940's to 1980 (Zwingle 1993). According to the donors' 'Club du Sahel' (quoted by Timberlake 1985), 5000 hectares of irrigated land were lost due to waterlogging and salinisation every year in the Sahel. This was equivalent to the area that was coming under irrigation each year during the late 1970s and early 1980s.
Land clearance for annual monocropping has led to the total eradication of perennial grasses such as Stipa tenacissima in parts of N. Africa as well as forest species (Le Houérou 1981). Forest species and some perennial grasses need shade and protection to regenerate and their seedlings cannot tolerate grazing, trampling nor high temperatures and high evapotranspiration. These species therefore die out permanently in cleared areas.
Nutrients are pumped out of the soil where annual monocropping is continually practised. Many Third World farmers don't have the means to use expensive inorganic fertilisers to replenish the nutrient supply. In Zimbabwe, the cost of replacing eroded nutrients on arable (annually cropped) land was US$ 20-50 per hectare per year (Stocking 1986 quoted by Young 1989).
Recent agricultural and forestry practises have resulted in the promotion of a few species on a large scale by the use of one mother plant or tissue culture. When native flora is cleared from the land to make way for a small number of species, genetic diversity is reduced. As a result, remaining species become more vulnerable to attacks from insect pests and diseases, and sources of food, medicine, etc, are also lost. The alternative is to introduce many species, and variations within the same species to promote genetic diversity. By making these seeds available to farmers, the farmers promote biodiversity in their fields. This gives farmers better returns from their land due to higher tolerance to drought, insect pests and disease.
Appropriate means for revegetating arid landsPerennials provide a permanent vegetative cover in arid lands and annuals can be intercropped. The roots anchor the soil and parts above ground reduce soil and sand movement.
Intercropping perennials with annuals leads to better use of light, water and nutrients due to the different spacing, height and root depth of the plants.
Research in Senegal has shown that organic matter and total mineral nitrogen flux are higher beneath trees such as Acacia senegal and Balanites aegyptiaca compared with surrounding soils (Bernhard-Reversat 1982 cited by Young 1989). Faidherbia albida is already well known for improving nitrogen and organic matter of the soil beneath its canopy. There is also evidence for higher contents of other nutrients like phosphorus beneath perennials such as Acacia tortilis (Young 1989). These are species that grow naturally in the semi-arid and arid areas of Africa. The improvement in fertility is due to one or more of the following: tree litter, bird and animal droppings, nutrient uptake from lower soil depths and nitrogen fixation in the case of Acacias and Faidherbia albida.
Experiments in Tanzania have shown that water run-off from unbrowsed bush fallow is 0.4% of the rainfall on gentle slopes. Water run-off rises to 1.9% from grazed grassland, 26.0% from millet fields and 50.4% from bare soil on gentle slopes (Edberg 1982). Perennials provide organic matter through leaf fall and dead roots which improves soil porosity, stability and water infiltration (Young 1989). Perennials also reduce sheet erosion and increase water penetration on hard soils by slowing water flow on slopes. Water is therefore retained in the soil for longer after the end of the rainy season (or during drought periods in the middle of the rainy season) resulting in reduced plant water stress.
Perennials protect annuals from desiccating winds. One farmer whose field was sheltered from the prevailing wind by perennials growing at Eden's field station, recorded a millet yield three times as high as another farmer whose field was exposed to the wind. That year, many farmers had to resow several times because the strong wind destroyed their seedlings. On the contrary, the farmer whose field was sheltered only had to resow the part of his field that was furthest away from the field station. In this way his millet grew taller and gave a higher yield than the others' millet.
Edible perennials have the distinct advantage of providing food in drought years when the annual crops fail. Intercropping edible perennials with annuals also ensures a variety and better nutritional balance in food supply. Edible perennials are also preferable because they are less likely to be cut down than non-food producers.
Perennial species are reported to have many other uses than those already mentioned. These include shade, fuel, timber, tools, chemicals, soap, tannin, fertiliser, dye, biocide, water purifier, illuminants and fibre.
Methods of establishing perennialsWhen local farmers play a large role in the establishment of perennials, they are more likely to maintain the plants afterwards especially if they can benefit from them. Farmers keep aggressive annuals in check when intercropping perennials, these annuals would otherwise smother young perennials making the area species poor. The most ideal situation occurs when the local farmers see it as in their own interest to establish and maintain the perennials, then no inducements are needed which makes it very economical to revegetate.
Non-irrigated on-site establishment compares favourably with other methods such as plant nurseries. Plant nurseries require water, plastic sacks which are expensive and pollute the environment, transport of the seedlings to planting sites and labour to look after the seedlings. On-site establishment is more economical for farmers and large scale operations and makes it possible to introduce perennials into the most isolated areas. This is because it can be done where water is not readily accessible. On-site established perennials tend to produce an extensive root system rapidly whereas the shoots grow more slowly. Seedlings raised in nurseries tend to produce large shoots which give greater evaporation and the roots soon become cramped in the plastic sacks. This means that plants established on-site are more likely to be able to reach moisture remaining in the soil after the rainy season has ended, than those raised in plant nurseries, because of their more extensive root system.
Regeneration from old rootstocks is a quick way of increasing biodiversity, but there is a limited number of old rootstocks left in farmers' fields. Where natural revegetation occurs from seeds that are naturally dispersed farmers don't necessarily obtain plants where they want them nor species of their choice. Some aggressive annual species enter into farmers' fields by natural dispersion and can smother perennials that have also spread by natural dispersion so that these perennials die out before the farmers have noticed them. However, farmers tend to remove aggressive annuals from around perennials that they have direct seeded themselves. The advantages with direct seeding are that it can be done in quantities that farmers choose over an unlimited number of years and the farmers can decide the exact location of each plant when they direct seed.
It is preferable for farmers to use tools that are available and familiar to them which will be affordable and easier to maintain. In this way farmers' knowledge is respected which makes it more likely that they will want to direct seed.
When a farmer makes the decision to direct seed by his own initiative, he is more likely to continue with direct seeding. The farmer will then require an extension worker (or some other training programme) to demonstrate how to direct seed each species. The extension worker needs to continue to support a farmer so that he can learn to do the whole process of direct seeding by himself. Then, direct seeding becomes self-sustainable after an initial phase. Other farmers who like the results of direct seeding become curious and ask the farmer who has already direct seeded questions about the uses of the plants and how they are sown. When these farmers start to direct seed, then it is not only self-sustainable, it is also contagious.
Farmers revegetating by direct seeding in response to Eden's research and extension work in NigerEden has been carrying out Direct Seeding Tests on 77 species since 1988 in order to find out which species are suitable for farmers in arid lands, with good results for several species. Eden collects seeds from several mother plants of perennial species. Two variables are tested at the field station that the farmers can replicate themselves. The first is non-toxic physical scarification or water treatment and the other variable is sowing depth.
The average annual rainfall was 223mm 1990-94 at the field station. At Tanout, 13km north of the field station, the average annual rainfall has been 209mm during the past 25 years 1968-1992. Species which have been established at Eden's field station are very likely to perform even better in locations further south where the rainfall is higher, making Eden's research applicable to other areas of Niger, the Sahel and other hot and dry areas of the world.
Local farmers make the initial contact with Eden by their own initiative. Eden provides start-off quantities of seeds that they themselves can reproduce. A local Dry Farming Agriculturalist is available at the field station to explain to farmers the uses of these species and demonstrate how best to direct seed them. The Dry Farming Agriculturalist then continues to support a farmer so that he can learn how to collect, deseed, carry out seed treatments, and direct seed the species eventually by himself.
Eden monitors the direct seeded species' germination and survivability in the farmers' fields. This data is of a different character to the Direct Seeding Tests carried out at the field station as these plants are exposed to livestock and more erosion. The farmers' results are interrelated with the results from the field station in order to determine the number of seeds needed to produce a mature plant in a farmers' field.
The number of farmers who have direct seeded has doubled each year since farmers first made orders for seeds in 1991. It has increased from 9 in 1991 to 101 in 1994 and there are 208 accepted orders so far for 1995. The number of species sown was 2 in 1991 and will increase to 9 in 1995. The number of villages direct seeding rose from 2 in 1991, 4 in 1992, 15 in 1993 to 21 in 1994. The villages were located up to 70km from the field station. The percentage of living plants in relation to seeds sown, after the first rainy season's germination was 9.5%. The mean yearly survivability rates of these plants have so far been 51% the first year and 85% the second. The proportion of orders for food was 67%, 51% of the orders were for environmental stabilisation and 92% for either of these goals, which confirms that Eden's solution is in harmony with the goals of local farmers. Other reasons given were for shade, hedge, fertiliser, timber, forage and medicine.
Farmers previously uprooted perennials or cut them down to ground level each year. Since 1992, increasing numbers of farmers have stopped this practice because they saw how perennials at Eden's field station protected an adjacent field from eroding wind resulting in higher yields of millet. As an example Malam Abdou who has direct seeded perennials in his field since 1993 can be mentioned. He has 261 perennials which he direct seeded that have survived the first critical year. Malam Abdou now also has 51 more perennials from regeneration of old rootstock. Since 1993 the number of perennial species has increased from three to thirteen in his field. Several of the perennials have grown three metres tall in two years. Farmers are also allowing naturally revegetated plants to mature in their fields.
SummaryFarmers in the Sahel need a reliable food supply from their fields. This goal is being compromised by the environmental degradation that is taking place in the Sahel. Perennial plants were seen as the appropriate tool to fulfil this goal, and direct seeding as the most suitable method to re-introduce them into arid areas. Direct seeding was selected because irrigation and/or plant nurseries waste water and other valuable resources. Eden's speciality is to research and develop direct seeding of drought and heat tolerant perennials that provide human food, passing on the results to interested farmers. A Dry Farming Agriculturalist demonstrates how to best direct seed these species. Eden has been carrying out a research and extension programme, to make it possible for farmers to establish edible perennials by direct seeding to stabilise degraded land. Farmers around the field station have been direct seeding since 1991. The numbers of farmers direct seeding has doubled yearly since 1991. They have direct seeded to stabilise their environment and/or for food. Farmers are also increasing biodiversity in their fields as a direct influence of Eden's work by natural regeneration from rootstocks and natural revegetation from seeds that are already in the ground.
Copyright © Eden Foundation