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Best Practices on Indigenous Knowledge MOST/NUFFIC (IK-Unit)


Pits for trees: how farmers in semi-arid Burkina Faso increase and diversify plant biomass[1]



Agricultural development, agroforestry, biodiversity, cultivation practices, desertification, natural resources, resource management, soil fertility, soil improvement


Introducing the practice

In recent years there has been a dramatic increase in the number of trees growing on farmers’ fields in certain villages in the Yatenga region of Burkina Faso. This is due in part to the systematic protection of natural regeneration by individual farmers and to the use of improved traditional planting pits, or zaï, for growing trees. Through this method farmers have rehabilitated degraded land and increased the diversity of trees.

In Burkina Faso, the fight against desertification is a constant preoccupation of farmers, government agencies, NGOs and development-project planners. The reduction in vegetative cover has reached alarming proportions in the north of the country, leaving the soils exposed to erosion by wind and water. The farmers described in this best practice live in the provinces of Yatenga, Zondoma and Lorum in northwest Burkina Faso.

Rainfall in the region is highly variable. The long-term average for the regional capital, Ouahigouya, was 560 mm between 1950 and 1987. Ouahigouya received 590 mm rainfall in 1997, but it was poorly distributed over the season and the harvests failed. In 1998 rainfall was an exceptional 969 mm, which led to a good harvest except in low-lying areas. The average population density in this region is 55 persons/km2. The grazing pressure on the natural vegetation is high; according to the 1992 national livestock census, the Yatenga region had 140,500 head of cattle, 591,500 sheep and 708,100 goats (INERA 1994).

During the dry season, the animals owned by the local farmers depend to a large extent on crop residues for fodder. The traditional practice of fallowing to regenerate soil fertility has disappeared and the possibilities for expanding cultivation to new areas are extremely limited. Rehabilitation of degraded land is the only option left to farmers who want to increase production by expanding their farming area.

During the last 30 years, substantial tree-planting operations have been carried out. Village woodlots have been planted and there have been several national schemes, including the National Village Forestry Programme and, more recently, the campaign entitled ‘8000 Villages, 8000 Forests’. Millions of seedlings have been planted, but survival rates have been poor. There are many reasons for this lack of success, but the main ones are the poor care of the seedlings after planting, uncontrolled grazing by livestock, cutting of trees to clear land and to obtain fuel, and, in particular, the fact that farmers were not involved in the activities in ways that encouraged them to take responsibility for them.


Content and approach

The practice described here involves the improved use of a traditional technique involving pits known as zaï, where naturally occurring seedlings are protected or where seeds are deliberately planted. In Burkina Faso, where the technique originated, farmers are experimenting with it and have managed to re-establish and protect abundant perennial woody biomass on their fields. They have done this by sowing tree seeds, planting seedlings, selectively protecting natural regeneration, and sowing and planting grasses in the pits.

Compared with the early 1980s, there has been a dramatic increase in the number of trees growing on farmers’ fields in parts of the Yatenga region. Many farmers have protected naturally regenerating trees but some have also made considerable efforts to grow trees in zaï. One example of a farmer-innovator is Yacouba Sawadogo, in the village of Gourga. He developed the practice of growing trees in pits, but several other farmers can also be considered to be pioneers in this field.

The innovations of Yacouba Sawadogo

In 1979 Yacouba Sawadogo started to use the zaï technique to rehabilitate land. At that time, his main aim was to produce more cereals, mainly sorghum and millet. By digging wider and deeper pits and by adding manure to them, he managed to achieve very good yields from fields that had previously been so degraded that nothing could be grown on them. His improvements allowed him to achieve food self-sufficiency for his family. In addition, Yacouba was pleasantly surprised that numerous tree species started to grow spontaneously in the planting pits. The tree seeds had been deposited in the pits by the run-off water, or they were contained in the manure that had been added to the pits. Yacouba decided to protect the young trees. In this way, he discovered the use of pits for growing trees (zaï forestier). Already in the first years, the results were spectacular and highly encouraging. His next step was to start collecting the seeds of numerous useful local species of fruit and fodder trees, which he introduced into the zaï in the next wet season. These species included sheanut (Butyrospermum paradoxum var. parkii), yellow plum (Sclerocarya birrea), grape tree (Lannea microcarpa) and various acacia species, but also fodder grasses such as Gamba grass (Andropogon gayanus) and Pennisetum pedicellatum.

Within a few years, the piece of barren land was gradually transformed into a 12 ha forest with a large variety of species. Yacouba then had to make a difficult choice because the trees and shrubs started to compete with his cereal crops. He opted for growing trees. Each year he placed the seeds of desired tree species into the zaï, as well as alongside the stone bunds he had constructed in his fields to prevent erosion. In the month of August, he split and replanted clumps of fodder grasses such as Gamba. In order to protect his forest from livestock, he surrounded it by cultivated fields which livestock are not allowed to enter during the growing season, according to local land-use agreements. During the dry season, he or his children protected the forest against uncontrolled grazing, woodcutting and hunting.

Since the devaluation of the West African franc (CFA) in January 1994, many farmers can no longer afford to buy commercial medicines. This has boosted an interest in medicinal plants. The farmer-innovators systematically protect and introduce into their fields all the species that can be used to heal common diseases (malaria, stomach ache, jaundice, etc.). The medicinal species named by the farmers include neem (Azadirachta indica), grape tree (Lannia microcarpa), yellow plum, eucalyptus (Eucalyptus camaldulensis), savanna mahogany (Khaya senegelensis), drumstick tree (Cassia sieberiana), and Guiera senegalensis. Yacouba Sawadogo has developed this activity more actively than anyone else. He has introduced species not previously known in his region and has focused on species that have largely disappeared because of droughts in the early 1970s and mid-1980s.


The role of indigenous knowledge

Around 1980, forestry professionals and other specialists in natural resource management working on the Central Plateau of Burkina Faso all predicted doom and gloom. They said that important species such as Acacia (syn. Faidherbia) albida were disappearing, that the stocks of baobab were ageing because of overexploitation and lack of natural regeneration, and that this was also the case for perennial grasses such as Gamba grass, which had retreated southwards over a distance of 200-300 km in the preceding 15 years. Twenty years later, farmers are actively protecting the natural regeneration of these species and several others, and they are planting Gamba grass along the stone bunds in their fields. In many fields, more trees were found in the year 2000 than in 1980. Twenty years ago, the expanses of severely degraded land were vast and expanding. Now, thousands of hectares of this land have been successfully rehabilitated by farmers in the Yatenga region using the zaï technique.

Transfer of knowledge

The rehabilitation of land and the improvement of the woody vegetation have greatly increased the social status of the farmers. Before they started to experiment and to invest, they were as anonymous as most farmers. Nowadays, their reputation extends beyond their provinces and even beyond the borders of Burkina Faso. They are in regular contact with the decentralized services of various ministries and have become focal points for improved natural resource management in their regions.

Yacouba Sawadogo receives many visitors from projects and from research institutions. Delegations of farmers also seek to learn from his experience. Each year he receives perhaps another 100 visitors who ask him for various parts of plants (leaves, bark, roots) for medicinal purposes. Most of these are farmers, but some are traders and office workers. Because of his knowledge in this field, Yacouba is in constant contact with well-known traditional healers who consider him their partner. The field of medicinal plants is secretive and Yacouba did not want to indicate which species he has introduced for medicinal purposes. He only indicated that he has planted species that reduce hypertension and even mental problems. Apparently, he does not ask for cash payments for his products and services, being more interested in the social esteem that he derives from this activity.


Achievements and results

This case proves that, as a result of indigenous innovation and initiative, it is possible within a fairly short time span (5-10 years) to produce a considerable quantity of diversified plant biomass that can be used for many purposes, including fodder. This facilitates the integration of livestock keeping and cropping systems, which is the basis of sustainable agricultural intensification.

The practice goes a long way towards solving the problem of firewood. The lack of firewood in this part of Burkina Faso is a serious problem for the women who must often walk long distances (10-12 km) to collect enough fuel for the home. As the wife of one of the farmer innovators remarked, ‘To have trees on the family fields is a great richness because we can save a lot of time that we can now spend on income-generating activities.’ The possibility of covering at least part of the family’s firewood requirements is one reason why the farmers protect and regenerate the woody vegetation. Most of the farmers prefer local to exotic species because they are better adapted to the environment and the farmers are well aware of the multiple uses to which they can be put.

The practice is efficient because it produces trees for multiple uses, including for medicinal purposes, and it provides extra income for full-time farmers. It is cost-effective because the seeds are readily available. And it is locally manageable because every farmer can use the zaï technique and also systematically protect the natural regeneration on his land in this way.

Impact of the practice on food security

As Yacouba Sawadogo explained, ‘in the days before the zaï technique, I was a part-time trader and I used all the income this generated to buy cereals to feed my family. Since I started treating the land with zaï, I am self-sufficient in food and sometimes I sell a surplus of cereals and cowpeas to cover my financial needs.’ One of the major advantages of the zaï technique is that it minimizes risks caused by variations in rainfall and ensures substantial yields on marginal lands.

The zaï have stimulated the production not only of cereals but also of leguminous crops such as cowpea (Vigna unguiculata). This is generally grown together with sorghum or millet as a cash crop. The substantial quantities of cowpea produced annually on the rehabilitated land contribute to the income of the farm families.

The zaï have indirectly had a positive influence on the crops produced by farmers’ wives. Because the men now concentrate on the zaï fields, the sandy soils not suitable for zaï have been allocated to the women, who use them to grow common groundnuts (Arachis hypogaea) and Bambara groundnuts (Voandzeia subterranea).

Impact on livestock husbandry

The zaï also have a positive impact on livestock-keeping. Many farmers stated that, before they adopted zaï, they had few animals. The investment in zaï has been paralleled by changes in their livestock husbandry practices. It is only by adding manure to the zaï that the farmers can obtain good yields. Farmers whose cattle were formerly managed by Fulani herders now keep their cattle at the homestead. Those farmers who keep sheep do this not only to raise stock to sell, but also to produce manure, which is either applied directly to the zaï or used for composting. It is now common practice among Yatenga farmers to collect the pods and fruits of specific woody species (yellow plum, acacia species, Piliostigma reticulatum, etc.) for livestock feeding. When passing through the animal’s digestive system, the seeds become softer and end up in the manure used in the pits. The seeds sprout and grow at the same time as the cereal crops, and the farmers protect them during weeding. The zaï have thus contributed to a stronger integration of livestock and cropping activities.

Impact on biodiversity

When the farmers started rehabilitating the tracts of degraded land (zî-peele in the Moré language), the land had only a few large trees from a very limited number of species. Yacouba Sawadogo counted only four: Balanites aegyptiaca, Lannea microcarpa, Guiera senegalensis and Combretum micranthum. Twenty years later, he has more than 60 species of tree on the same land. Yacouba has introduced into his forest several medicinal species which had disappeared from the region. He collected these during his travels outside the Yatenga area. When people come to visit his farm during the wet season, he asks them to dig some planting pits, plant some trees or sow some seeds that he collected.

Impact on income generation

Several farmers mentioned that they have also sold wood for the construction of roofs, sheds and the like. On an annual basis, this brought cash income of CFA 20,000-40,000 (approx. USD 30-60) per farmer, but the amounts can vary according to the amount of timber in their fields and to demand and supply on the local market. The main species for construction purposes are exotic, such as neem and eucalyptus, but certain local species are used for making chairs, mortars and pestles. The current drive to regenerate the woody vegetation is also linked to the possibility of gaining some cash income. The women have a stake in this as well: they collect leaves of the baobab, flowers of the kapok (Bombax costatum), and fruits of the sheanut (Butyrospermum paradoxum var. parkii) and the locust bean (Parkia biglobosa) tree for home consumption and to sell at local markets.

Farmers’ motivation

The farmers’ reasons for regenerating the vegetation differ and depend largely on the amount of land they have. Yacouba Sawadogo owns his land and has more than enough to meet his family’s subsistence needs. He aims to create a multipurpose forest of 20 ha and gives priority to planting trees at the expense of producing cereals. He plans to invest more in growing medicinal woody plants and he would like to reintroduce wild fauna (small deer, hyenas, birds, etc.) into his forest.

Farmers who have only usufruct rights to the land they are farming generally hesitate to plant a live fence around the fields. This would make it easier to protect the trees against uncontrolled grazing but, in view of the local land-use customs, planting trees on and around fields could evoke negative reactions from the landowners. The farmers can protect regeneration, however, which is different from the art of planting.

The battle against land degradation has not been completely won. Farmers involved in land rehabilitation continue to face many constraints, such as uncontrolled livestock grazing and the cutting of trees for firewood by outsiders. These are problems that can be solved only at village and intervillage level. Nevertheless, the environmental situation appears to be less gloomy now than 20 years ago because farmers have shown that something can be done.


Source of inspiration

It would be possible to transfer the practice, but there certainly would be conditions and prerequisites to consider.

It is now common to selectively protect seedlings that have regenerated naturally in the pits known as zaï, but only a few farmers deliberately sow tree seeds in them. Nevertheless, this practice has considerable potential.

If you think that this case could be useful in a different context than the one described here, please get in touch first with the contact person listed below (Administrative data). Intellectual property rights could be an issue.


Administrative data

Contact person

Chris Reij

Vrije Universiteit Amsterdam,

International Cooperation Centre

De Boelelaan 1105

1081 HV Amsterdam

The Netherlands

Tel.: +31 20 4449078

Fax: +31 20 4449095

E-mail: cp.reij@dienst.vu.nl


Other partner(s) involved in the practice

Ann Waters-Bayer

ETC Ecoculture

P.O. Box 64

3830 AB Leusden

The Netherlands

Tel.: +31 33 4943086

Fax: +31 33 4940791

E-mail: ann.waters-bayer@etcnl.nl; waters-bayer@web.de


Person(s) who have described this Best Practice

Hamado Sawadogo

Frédéric Kambou

INERA (Institut National d’Etudes et de Recherches Agricoles)

Tougan, Burkina Faso


Fidèle Hien

Formerly working for INERA, Minister of Environment and Water (now

Member of Parliament)

Burkina Faso


Adama Sohoro


Tougan, Burkina Faso

[1] This case is an adapted version of an article published in: ‘Farmer Innovation in Africa. A source of Inspiration for Agricultural Development’. Chris Reij & Ann Waters-Bayer (eds.), 2001. Publisher: EARTHSCAN, Earthscan Publications Ltd, London (UK) / Sterling, VA, USA. www.earthscan.co.uk



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