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Diversity of soil fertility management practices in sudanian zones of Benin (Western Africa).

Tropentag 2007
University of Kassel-Witzenhausen and
University of Göttingen, October 9-11, 2007
Conference on International Agricultural Research for Development
Diversity of soil fertility management practices in sudanian zone of Benin (Western Africa)
, Kindomihou, Jean-Marie Ambouta Karimou
and Brice Sinsin
University of Abomey-Calavi, Faculty of Agronomic Sciences, Laboratory of Applied Ecology, Benin.
Faculty of Agronomy, Department of Soil Sciences, Abdou Moumouni University, Niger.
Various soil fertility management practices are observed in the Sudanian agrarian zone of Benin.
This study highlights some traditional practices such as agroforestry, fallow, animal parking, use
of crop residues as organic fertilizer, post-harvests of grasslands, farming associations and
rotations, which were commonly used by 67% of farms. Five variant of agroforestry system were
observed: (i) woody parks with Parkia biglobosa, Vittellaria paradoxa, Adansonia digitata and
Ceiba pentadra; (ii) fields pioneers on forest territories; (iii) agricultural plots planted with fruit-
lofts of Anacardium occidentale and Mangifera indica; (iv) shifting cultivation using Eucalyptus
camaldulensis, Acacia auriculiformis and Leucaena leucocephala; (v) fallows planted with
Tectona grandis and Gmelina arborea. This traditional system is more largely used, as well as
planted fallows of fruit trees, collective grazing fallows under contracts and fixed parking of
sedentary herds. Crop residues and domestic wastes are largely exploited. Revenues from
grasslands post-harvests were higher than those from leguminous plants and foster the control of
flows of post-harvests residues and the development of mechanisms that guarantee grasslands.
The cereal-leguminous plants account for 63% of farming associations, and are observed where
the organic manure is less commonly used. Successions of cotton by cereals are associated with
significant depletion in mineral while those of cereals by leguminous resulted in nitrogen gain.
The improved practices such as improved parks, composting, cropping of plants that enhance soil
fertility (i.e. Vigna unguculata, Glycine max, Mucuna pruriens, Cajanus cajan, Aschynomene
histrix and Moringa oleifera) were adopted. Adoption rate of “Biological Cotton” increased by
8% per year and yielded 600 kg of cotton per ha while the non biological cotton showed 980 to
1200 kg per ha. It reduces investment costs, risks in animal and human health and enhances
agroforestry practices. Improved cropping techniques such as thinning, flat ploughing,
application of optimal quantities of mineral manure and of organic manure were successfully
adopted by 25%, 52%, 71% and 55% of farmers respectively.
Keywords: Benin, diversity, fertility, management, practice, soil, Sudanian agrarian zone
The agricultural landscape in northern Benin highlights some traditional as well as "improved" soil
fertility management practices which have proven as consuming less space. Their importance was
already indexed in sahelian traditional societies (Boulier & Jouve 1990, Landais & Lhoste 1993).
These practices define farming systems. The landscape was affected by the abandonement of fallow
areas, developing overused areas and increasing the use of unproductive land. To maintain the soil
fertility in the current increasing demography context requires some detailed knowledge on practices
for sustainable landuse. This work presents the typology of soil fertility management practices
throughout monographs of farming systems and an analysis of the Sudanian agrarian space in Benin.
Study area
The district of Kandi in northern Benin (10°45'-11°27' Lat. N; 2°38'-3°16' Long. East) covers 3480
km² with 76% used for agriculture and livestock breeding. Average temperature is 28.8°C. Relative
humidity ranges from 7 to 100%. The sunny period during research accounted for 2.900 hours.
Potential Evapotranspiration was 1373.75 mm and Rain ranged from 900 to 1200 mm. Soils are
brown mineral on slopes, skeletal on plates, deep on plains, hydromorphic in depressions. Vegetation
comprises of shrubby savannas, timber plantations, post-farming and riparian forests. Human density
ranges from 52 to 65 habitants/km
, balancing the national rate of 48 habitants/km
. Nine
Sociocultural groups live in the study area: Mokolé, Dendi, Peuls, Gando, Bariba, Djerma, Yoruba,
Boko and Haoussa. Mokolé, Bariba and Gando, all of these are farmers, and in addition the Peul, who
are lifestock breeders. The Dendi, Yoruba and Haoussa are also tradesmen. The land use is based on
heritage, loans, gifts and first occupation. Male groupings are devoted in inputs provisioning, cotton
marketing and in financing community activities. Women work in food transformations, marketing
and the elimination of illiteracy and are highly open to new technologies.
Target groups, surveyed stakeholders & plots, Data collection: Investigations were carried out on 3
scales: (i) 5 agro-systems (one per subdistrict) were sampled: Fouet, Alfakoara, Gogbèdè, Padé and
Lowa, with a total of 316 stakeholders; (ii) 31 stakeholders were chosen using principle of
representativeness and discrimination by diversity in plots, crops and followed husbandries; (iii) Plots
previously spread by wastes, composts, improved technical procedure were sampled. Old farms,
cropping techniques (sowing, fertilization, crops maintenance, phytopathology, harvests, and post-
harvest operations) were recorded and monitored by questionnaires. A 5 months survey, with 5 days
per month per agro-system lead to record the current soils fertility management practices and
strategies, profiles, applied techniques and cultivation actions. The economy of compost and cotton
was estimated based on the market prices during 1996-2002.
Data analysis: Practices of soil fertility management were analyzed using the traditional diagram
Opportunity-Method-Effectiveness suggested by Landais (1986). We determined (i) practices; (ii)
external description of practices and (iii) descriptions of their effects and consequences. An
alternative method was highlighted by in situ investigation of effects of the practices on the systems
status in time and space, taken .from concepts of "experiments without interventions" and
"comparative analysis" (Landais et al. 1988).
1. Traditional Practices of soil fertility management
A) Five agroforestry systems occurred in Kandi (Fig. 1): (i) Park of Parkia biglobosa, Vittellaria
paradoxa, Adansonia digitata and Ceiba pentadra on agricultural lands (PAL) with agro-
stockbreeders and lifestockbreeders; (ii) Fields pioneers on forest lands (FPFL) set up by the UNSO
project; (iii) Planted Plots of Fruit-lofts (Anacardium occidentale and Mangifera indica) (PPFL) with
farmers; (iv) Shifting cultivation alterning crops and woody hedges by Eucalyptus camaldulensis,
Acacia auriculiformis, Leucaena leucocephala (SCWH) with farmers; (v) Planted fallows of Tectona
grandis and Gmelina arborea (PFTG) with farmers and agro-stockbreeders. The Park system was
widely practised, followed by planted fallows, plots planted of fruit-lofts, and shifting cultivation with
woody hedges. B) Fallows cover 0.4% of total area with 26% of farmers having agricultural land
exceeding 15 ha. Lands used 7 years returned in 10 years fallow with farmers and agro-stockbreeders;
those used 5 years’ for 2 years with agro-stockbreeders. 25% of farmers used Planted fallows and
collective grazing fallow, which is governed by contracts with stockbreeders. Short fallows (<7 years)
on small areas (<6 ha) belonged to 62% of stakeholders, and the shortest one (3-7 years) were
strongly grazed. C) In turning parking (Fig. 2), post harvested fields were grazed for 15 hours per
day in October-November and bovine transhumance every 15 days. Grazing and fallow respectively
in dry and rainy seasons occurred on 1.5 to 6 ha. During seasonal parking (Fig. 2), moving herds
grazed under contracts for 6 dry season weeks, some post harvested fields, which were used to
produce maize. In stationed parking (Fig. 2), apart from a lack of carts, wastes were well distributed.
Corn fields were grazed in dry season by moving herds (952.8 UBT) from Burkina Faso, Niger, and
D) In residues hiding and domestic wastes, balking was preferred to ploughing (61% of farmers).
E) Revenues of post-harvest grazing control residues flows. The running costs depended on the type
of plot, herd size, duration and grazing frequency. To graze leguminous plots costs more than grazing
corn and cotton plots (Table 1). F) Farming associations highlighted cereal-cereal and Cereal-
leguminous in systems out of chemical manure use (Fig. 3). Corn, sorghum, groundnut and bean were
associated, and more frequently with 67% of stakeholders. G) Successions were Cotton/Cereal and
Cereal/leguminous/cereal. Leguminous were frequently associated with sorghum and corn
2. Improved Practices of soil fertility management
A) Improved parks ruled where compost was not used (Fig. 4). Monthly, 4 bovines were stationed
on 5 m diameter carpet of farming residues and fodder straws (Andropogon spp, Panicum spp,
Hyparrhenia, Pennisetum spp). Litter was accumulated per week in rainy season and every fifteen
day in the dry season to each 20 cm thickness. Food complementation enriched in coarse elements
was provided to animals. Manure was stored and conserved under hangar in season of rain and in pits
Fig. 2: Animal parkings in Kandi (N=31)
30 35 40 45 50 55 60
Stational P.
Turning P.
Seasonal P.
Adoption rate (%)
Fig. 1: Agroforestry parks in Kandi (N=31)
0 20 40 60 80 100
Adoption rate (%)
Fig. 3: Adoption rate of crops associations
0 10 20 30 40 50 60
Table 1:
Post harvested grazing revenues in soil fertility
management in Kandi
Cotton December
- February <50 2-4 h
Maize October -
November ≤50 1-4 h 1-2
grazings 0.54-0.69
Sorghum November
- January <50 2 h 1 grazing 0.62-0.92
Bean &
December ≤25 2 h 1 grazing 1.15 -1.54
dunghills in dry season for application in April-May. B) Composting was used in agricultural soils
and interested 50% of women (Fig. 4). Two pits of 2 m x 1,5 m x 1,5 m on branches lattice, were
equipped with cereal straws and chopped grasses (Panicum spp., Pennisetum spp., Hyparrhenia spp.),
in rowed layers and strewn with old manures. A layer of rough manure of 5 cm succeeds 20 cm
thickness layers. The grinding stone was sprinkled with 4 water buckets and covered with sheets of
Borassus aethiopum, Hyphenae thebaïca or with soil. Each grinding stone was stirred up after 3
weeks. The compost rate of 3t/ha was used to produce biological cotton, and 2t/ha for the corn before
sowing. Averages of biological cotton areas were 0.5 to 2.5 ha. Yields ranged from 1.5 to 2 t/ha in
corn grain and 0.5 t/ha for biological cotton. Invasive plants pressure was reduced on treated plots.
Compost production costs 92.31 to 117.31 €/ha and for its utilization about 26.92 €/ha.
C) Various Improving plants were adopted in rate depending on plants and farms (Fig. 5): Vigna spp
(52%), Mucuna utilis and M. pruriens (35%), Glycine max (39%), Cajanus cajan (32%),
Aschynomene histrix (16%) and Moringa oleifera (16%). These plots were used to produce
exclusively corn and biological cotton biannually. D) Biological Cotton production occurred where
no chemical fertilisers were used for 3 years. Activities were: Ploughing with 10 t/ha of compost,
sowing on 40 cm x 40 cm, applying weeding twice before a weeding-ridging, and a pulverization
every 7 days of 1 kg/40L/ha of Azadirachta indica seeds pulp. Cotton was harvested after 180 days,
and subsequently stored, packed and labelled. Biological cotton was produced in 29% of villages.
Adoption rate depended on years and ranged from 45% in 1996 to 53% in 2000 with increased area
(157%). Yields averaged 285 kg/ha in 1996-1997, 425 kg/ha in 1997-1998 and 610 kg/ha in 1998-
1999. Yield Modelled with Logarithmic curve resulted in 250 kg/ha in 1996 and 1 t/ha in 27 years.
Comparative profitability was 13.5% lower than 33.5% for the non biological cotton. E) The
improved cropping techniques depend on the prevailing agro-system. About 25% used thinning out,
52% ploughed flat, 71% used chemical manure while 55% used organic manure. Preference was high
for balking with the flat ploughing by 65% of farmers while thinning is missing with stockbreeders.
1. Traditional Practices of soil fertility management
(a) The agro-forestry park provides wood, fodder and medicinal products, reducing the failure level of
populations. In semi-arid Kenya, corn fields are strewn with trees using 2 times more rainwater than
in full overdraft (Wolf et al. 1990). In sudanian Senegal, the best mixture productivities resulted from
maintenance of 25 trees/ha (Akpo 1993). (b) The interest for animal parking might be related to the
inexpensive transfers ensured by animals with an even waste plots distribution (Landais & Lhoste
1993). Since 600 kg of dry matter by UBT are deposited annually, the improvement of soil fertility
management requires increasing herds’ size. (c) The hiding of crop waste products was limited by
skeletal soils flat ploughing, and the Park W herds i.e. bovine and elephants overgrazing. (d) The
revenue of post-harvest grazing reduces grazing pressure on agricultural wastes, guarantying mineral
contributions and reinforcing the soil structural stability (Pieri 1989). Mixing chemical and organic
Fig. 4: Manure production practices in Kandi
19 17 9 6
0 10 20 30 40 50 60
Adoption rate (%)
Lowa Alfakoara Fouet Pade Gogbèdè
Fig. 5: Improving plants used in Kandi
0 20 40 60 80 100
Cajan Pea
Adoption rate (%)
Alfakoara Gogbèdè Fouet Padé Lowa
manures produces 1.5 to 2 t/ha for corn against 1 t/ha from chemical manure in the rate of 200 kg/ha
(Gandy 1993).
2. Improved Practices of soil fertility management
(a) Change in the rate of improved parks adoption from stockbreeders to farmers might be related to:
(i) a weak cart distribution and low manpower availability; (ii) a weak sensitizing and educational
level of owners and managers (17%). Success in southern Mali depended on the herds grouping
management and carts availability (Landais & Lhoste 1993). (b) Both composting and biological
cotton techniques were practiced together where land pressures occurred. Outputs were economic for
corn which was produced without urea (1.5 t/ha) and the same applies to groundnuts (1 to 2 t/ha)
(Gandy 1990). (c) Biological cotton production was constrained by lack of equipment, land tenure
with doubled bloom, low availability in Azadiratcha indica seeds and natural insecticides including
Capsicum frutescens which cost 0.25 to 0.45 €/litre. Debt and health risks were minimized and pit
inputs and compost dunghills were easily accessed. Plot insulation, cropping turning and doubled
bloom needed to be amplified. The biological cotton production requires the use of both chemical and
organic manures. (d) Improved cropping techniques were slightly adopted. Weak thinning out
application might be related to the low manpower/area ratio (57%) and the weak rate of illiteracy
elimination (Jouve 1993). Balking was preferred to flat ploughing while the respect in the use of
required amounts of chemical fertilisers was financially constrained.
Farming systems in Kandi integrated various practices for soil fertility management such as: (i)
"traditional" (agroforestery, fallow, parks, crop waste products, pooling and followings farming); (ii)
"improved" (improved park, composting, improving plants, improved cropping techniques and
biological cotton). The practice of biological cotton saved investments, limited health risks and
developed agroforestry. In the transition to biological agriculture, fertilizing using locally available
resources could be well developed and the constraints to manure transportation could be lifted.
Complete equipment for a harnessed production and certification are also needed.
Financial supports from AUPELF UREF and Netherlands Volunteers are kindly acknowledged.
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Full-text available
Farmers' Practices : A View of a New Current in Agronomic Research This article's introduction recounts the changes that have gradually led researchers from the Agrarian Systems and Development Department of the Institut National de la Recherche Agronomique, who were working on various questions about the conditions and types of agricultural development, to be more and more interested, as they were adopting a systemic approach, in farmers' practices. The first part of this article provides the methodological and conceptual reference marks necessary for analyzing these practices. This analysis is placed within the broader framework of building a simple model of how farms function. An approach is proposed in three complementary parts centered, respectively, on the type, efficiency and opportunity of agricultural practices. Various considerations about the study of these practices in time and space close this presentation. In the second part, devoted to the study of combinations of farmers' actual practices, the foregoing principles are used to reinterpret the various approaches aimed at assessing the technical efficiency of these combinations. These principles are then used to present the concept of a system of practices and to show its typological interest. The authors emphasize both the complementary fo these approaches and their operational interest for development and especially for the technical and economic advice given to farmers.
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Evolution des Systèmes de production sahéliens et leur adaptation à la sécheresse. R3S-CORAF-CILSS. CIRAD/DSA
  • F Boulier
  • P Jouve
Boulier F. & Jouve P., 1990. Evolution des Systèmes de production sahéliens et leur adaptation à la sécheresse. R3S-CORAF-CILSS. CIRAD/DSA. 144 p.
Utilisation des résidus de récolte dans la fumure organique. Savanes d'Afrique, Terres fertiles in Actes des Rencontre Internationales
  • M Gandy
Gandy M., 1993. Utilisation des résidus de récolte dans la fumure organique. Savanes d'Afrique, Terres fertiles in Actes des Rencontre Internationales. CIRAD. Montpellier, France. 298-313.
La lutte contre l'aridité au Malgreb et au Sahel par l'adaptation des systèmes de production agricole. Pratiques paysannes face à l'aridité et aux aléas climatiques
  • Jouve Ph
Jouve Ph., 1993. La lutte contre l'aridité au Malgreb et au Sahel par l'adaptation des systèmes de production agricole. Pratiques paysannes face à l'aridité et aux aléas climatiques. CIRAD-CNEARC. 39-70.
Méthodes pour la recherche sur les systèmes d'élevage en Afrique intertropicales
  • E Landais
Landais E., 1986. Méthodes pour la recherche sur les systèmes d'élevage en Afrique intertropicales. Actes de l'atelier de M'bour (2-8 février 1986) Maison-Alford, France, Etudes et Synthèses de l'IEMVT, 20 : 733p.
Methods for evaluating multi-product tree yields from linear agroforestry technologies in farmers' plots
  • F G W Wolf
  • J H Roger
  • S J Scherr
Wolf F.G.W., Roger J. H. & Scherr S. J., 1990. Methods for evaluating multi-product tree yields from linear agroforestry technologies in farmers' plots. ICRAF WP. n o 50, 60p.