How to produce more biomass for direct seeding mulched based cropping system in sub-saharian Africa ? Example in North Cameroun

In North Cameroon, from 2001 to 2006, more than 250 farmers tried direct seeding mulchbased cropping systems (DMC) in their fields. DMC systems were based on farmer traditional rotation i.e. cereal//cotton. Farmers compared on their own field cereals (maize, sorghum, millet) cultivated with conventional techniques and the same cereal conducted with DMC techniques i.e. : i) intercropped with a cover crop (Mucuna pruriens, Brachiaria ruziziensis, Crotalaria retusa, Vigna unguiculata, Dolichos lablab), ii) sowed without ploughing from the first or the second year of experimentation. Associations were made for the following objectives: i) produce aboveground biomass to produce mulch for the following crop (mainly cotton), ii) improve the soil's physical and chemical quality through the contribution of associated plants, iii) produce forage, iv) help to control weed, v) protect the soil surface against erosion and rain impacts, vi) produce grains for human or animals consumption. Each of the 5 cover crops used are different regarding their fulfilments of above objectives and their adaptation to North Cameroon local agro-climatic conditions (rainfall from 700 to 1200 mm). Thus, Brachiaria ruziziensis produces aboveground biomass in quantity (4-5 T of dry matter/ha even when associated with cereal) and quality (persisting of the mulch for over one year after production). Further, it seems to be very efficient in controlling Striga hermonthica and it is a good forage. However, it can impoverish the soil if its biomass is exported several times without any fertiliser or manure input. Crotalaria retusa is a nitrogen fixing legume and thus can improve soil fertility. Furthermore, this plant is non edible for cattle, which is an advantage for farmers who cannot protect their field from grazing during the dry season. C. retusa is also very efficient to fight against other weeds. Six years of experimentation with farmers permits us to produce practical recommendations for intercropping of cereals with cover crops: sowing date, crop type, tolerance to herbicides, limitation of competition with cereals, etc. This experimentation has also allowed us to see what is the behaviour of the 5 cover crops in farmer's conditions. (Résumé d'auteur

Les filières gomme arabique au Nord-Cameroun. Impacts du fonctionnement des filières gomme sur l'organisation des producteurs, la gestion des forêts naturelles et l'encouragement des plantations d'acacias

International audienceDes études de filière ont été menées au Nord-Cameroun en 2007 et 2008, pour déterminer quelles étaient les pratiques réelles des cueilleurs et des acheteurs de gomme arabique. L'essentiel des quantités prélevées provient des formations naturelles à Acacia seyal (qui produit la gomme friable de qualité médiocre) et emprunte une filière informelle vers le Nigéria. La cueillette est effectuée en majorité par des enfants et des femmes, qui profitent d'une autre activité en brousse pour compléter leurs revenus. Cette filière informelle présente des avantages pour les vendeurs, tels que le préfinancement de la campagne, le paiement au comptant et la multiplication des points d'achat. Les planteurs d'Acacia senegal (qui produit la gomme dure de haute qualité) constituent une population très différente de celles des cueilleurs. Il s'agit en majorité d'hommes d'âge mûr, relativement aisé. La filière officielle qu'ils utilisent est rigide, les points d'achat sont peu nombreux et éloignés des lieux de cueillette, achats et paiements ne sont pas garantis. Cette filière est fortement taxée de façon officielle et officieuse, ce qui la rend peu concurrentielle par rapport à l'exportation illégale et entraine une mévente de la gomme dure pour les producteurs. De ce fait, la majorité des plantations a été abandonnée. La filière officielle ne peut être performante que si elle adopte les mêmes méthodes d'achat que l'informelle, en développant le préfinancement et le paiement du solde au comptant et en multipliant les points d'achat. Mais surtout, si les Etats ou des projets veulent encourager la gestion durable des peuplements naturels d'acacias ou le reboisement de terres dégradées, ils doivent accepter d'appuyer la sécurisation foncière, de réduire les taxes et tracasseries qui plombent les filières officielles de la gomme, tout en encourageant les producteurs à se positionner sur des marchés plus rémunérateurs, de type commerce équitable ou biologique. Ceci est tout à fait possible pour cet épaississant alimentaire qui entre dans la fabrication de produits à haute valeur ajoutée

Sustainability of conventional agriculture and conservation agriculture in small-scale cotton-based regions in west and central Africa : lessons from northern Cameroon

Sustainability of agricultural practices is a suitable concept to evaluate both agronomic and economic performances of conventional agriculture and conservation agriculture. In this study, the concept of sustainability is analysed through its three main components: economic sustainability also called economic efficiency, dealing with the ability of the farming system to ensure sufficient and competitive output production to fulfil market and population needs; social sustainability or social equity, dealing with agricultural ability to ensure equitable revenue or return to different stakeholders of the agricultural production chain; ecological sustainability, dealing with intergenerational preservation of the environment referring here to the sum of natural resources used to ensure agricultural production such as soil fertility. Ecological sustainability is commonly the only aspect of sustainability taken into account by agronomists. Sustainability of conventional agriculture is addressed in this study in small-scale cottonbased agriculture surveys in northern Cameroon. Economic efficiency of cotton in conventional agriculture is analysed through a multi-year data base of a permanent agricultural survey of SODECOTON (Cotton Development Company), while social equity is addressed based on different production cost distribution within cotton production stakeholders. Ecological sustainability is analysed through agronomic variables such as yield variation over time, and mainly soil fertility evolution. Results of the study revealed that economic efficiency of cotton cultivation in conventional agriculture, after attaining acceptable levels in the early 1990's mainly due to high yields and prices and low inputs cost, is now declining. Fertiliser prices for example varied from 500 US $per ton in 2005 to more than 1000 US$ per ton in 2008. Social equity even if strongly reinforced by an equalizing prices approach and inputs cost determination system, is limited with a high ecological differentiation between ecological areas varying from 600 mm rainfall in the far north to 1200 mm rainfall in the south of the cotton belt, hence affecting different respective yields. As for soil fertility, decreasing yields and increasing expenditures on fertilisers and other water harvesting and soil conservation technologies revealed progressive weak response of soil resource to cropping systems management. Conservation agriculture appears to be a suitable alternative to conventional production systems for small-scale cotton based agriculture to attain the three main objectives of a sustainable agriculture, since it can ensure economic efficiency of the farming system, a better social equity and a better soil resource management. (Résumé d'auteur

Structured or spontaneous dissemination of DMC techniques in small-scale cotton-base agriculture ? The northern Cameroon case study

The northern Cameroon cotton-based agricultural region, as well as the whole of the western and central African cotton belt is mainly characterised by a cotton based agriculture extension program implemented and monitored by the cotton companies. The companies' names or field approaches may differ from one country to another, but they all operate a strong extension team and program that follows the cotton crops from seedling through harvesting, offering relatively higher performances to cotton sectors. Such extension performances can be seen on the large areas covered, involving a large number of cotton farmers and relatively intensive production practices (with high level of fertilisers and other chemical inputs, high average yield, etc.). Direct seedling-Mulch based-cropping systems (DMC) extension program in the northern Cameroon began in 2007 within the Soil Conservation Project (PCS) following the pilot experimental phase in the Water-Soil-Tree Project (ESA) from 2002 to 2006. Since the two soil conservation projects were monitored by SODECOTON (cotton development company), the newly emerging DMC extension program had to choose between two different extension approaches: a structured extension approach laying on Sodecoton performed and experienced extension team which implies well defined technical message to disseminate; and a spontaneous extension, laying on progressive construction of on-farm technical messages, permanent adaptive processes on cropping systems, and hence little need of a highly structured extension team but rather of an agricultural based progressive approach to change. This study examines the two approaches not by offering a final answer to the best suitable extension approach, but through investigations on the advantages and constraints of each approach and common determinants of DMC extension programs like seed supply and community based experimentations and up scaling. The study is based on seven years of experience on DMC experimentation and extension program in northern Cameroon including on-farm trials and spontaneous disseminations around the village-based cropping systems trials as well as three years of DMC pre-extension program. According to the study, structured dissemination approach may be adapted to dissemination through an extension team performing its activities on simple but definitive cropping systems. Consequently, any additional amelioration within the system may need high input investment (skills and materials). This may be of interest in familiarising farmers with DMC techniques but may limit DMC appropriation by them since simple and rigid options may not fulfil their main constraints like less fertiliser use, and appropriate integrated weed control. DMC spontaneous extension approach aims at permanent adaptation of DMC techniques to each given context. This means that various DMC options may be suited to different contexts, thus excluding or avoiding a single "able to disseminate" technical message. Therefore, for an extension team, the need of permanent on-farm construction of technical messages may imply new adaptive skills for taking into account the diverse socio-economic and ecological constraints of farmers which are always ignored in the structured extension approach. On the other hand, this maximum farmer's engagement in decision-making implies minimum input from the structured extension agents' team. Thus, the farmers' uptake rate of techniques and know-how will be determined either by extension agent dissemination rate (area or farmers he/she is able to supervise) for the structured extension approach or by the ability of the DMC options to respond to farmers constraints for spontaneous extension. (Résumé d'auteur

Boosting traditional management of Sahelian Faidherbia parks

Traits and functions of Apple?ring acacia (Faidherbia albida (Del.) Chev.), iconic species of sahelian agroforesters, are well known of agro?pastoralists farmers and scientists. Traits include its deep taproot system reaching the water table on alluvial soils, its inverted phenology, and the leaves being present in the dry season and absent during the rainy season, and its ability to vegetative propagation (root suckers, coppices of stumps and branches). For functions, its general positive impact on associated crop, production of forage (leaves and fruit) and firewood are also widely recognized. However, the area extension of Faidherbia agroforestry systems (parklands) is still far below what it could be, despite the isolated actions of many extension services and NGOs. The example of northern Cameroon shows that research on crop productivity under Faidherbia helped changing the perception of this tree by services and operators of agricultural development, in the 1990s. Then it was possible to "boost" the restoration of these parklands on a large scale, mobilizing public funding, associations and farmer organizations and subsidizing (even at a low level) Assisted Natural Regeneration. The results of socio?economic surveys and pruning trials, conducted in 2012, confirm, at least, the interest of farmers for pruning the trees and fire?wood sustainable productivity of this method. Demand of farmers, on the right of pruning trees and freely use the wood harvested has been taken into account in the draft amendment to the Law on the forest regime, introduced in 2012, to the Cameroon parliament. These studies on Faidherbia albida have helped Cameroonian farmers to keep more than one million young trees, but also have helped to change the law in the sense of increasing the rights of peasants on the tree. This concern planted trees, often exotic, but also natural species kept and maintained by farmers, such as shea?butter tree (Vitellaria paradoxa) and many other multipurpose species. (Texte intégral

Abandon ou extension des plantations d'acacias au Nord-Cameroun : tout dépendra du fonctionnement des filières gomme arabique

Au Nord-Cameroun, plusieurs projets destinés à lutter contre la pauvreté et la dégradation de l'environnement ont encadré la mise en place de milliers de petites plantations paysannes d'Acacia senegal, entre 1990 et 2006. Cependant, depuis 2007, la plupart de ces plantations ne sont guère entretenues et n'ont pas été saignées pour la collecte. Les superficies plantées baissent et la filière formelle de gomme dure, issue de ces plantations, périclite. En 2008, la présente étude a comparé les caractéristiques des filières illégale et légale. Les résultats montrent que l'essentiel des quantités prélevées provient des formations naturelles à Acacia seyal (produisant la gomme friable) et emprunte une filière informelle vers le Nigeria. La cueillette est surtout effectuée par des enfants et des femmes. Malgré le faible prix d'achat de la gomme, cette filière présente des avantages pour les vendeurs désargentés, tels que le préfinancement de la campagne, le paiement au comptant et la multiplication des points d'achat. Les planteurs d'Acacia senegal (produisant la gomme dure de qualité) constituent une population très différente. Il s'agit en majorité d'hommes âgés, aisés, partenaires des projets. La filière officielle qu'ils empruntent est rigide, les points d'achat sont peu nombreux et éloignés des lieux de cueillette et les achats et paiements ne leur sont pas garantis. Cette filière est fortement taxée officiellement et officieusement, ce qui la rend peu concurrentielle vis-à-vis de l'exportation illégale et entraîne une mévente de la gomme. Le prix payé au producteur (0,2 à 0,5 $US/kg) est très inférieur à celui du marché international (1,5 à 4,5$ US/kg). La filière officielle ne peut être performante que si elle adopte les méthodes d'achat de l'informelle. Si l'État et les projets veulent encourager la gestion durable des peuplements d'acacias ou le reboisement, ils doivent sécuriser le foncier, réduire taxes et écueils commerciaux, tout en encourageant les producteurs à s'organiser et à se positionner sur des marchés plus rémunérateurs, de type commerce équitable ou biologique. (Résumé d'auteur

Optimisation du couple animal-outil. Applications aux cas du zébu, de l'âne et du cheval au Nord-Cameroun

Dans les années 1980, les performances des animaux de trait dans les systèmes de production de la zone subsahélienne d'Afrique francophone étaient méconnues. De plus, la place de l'animal, dans les stratégies de développement de la traction attelée, apparaissait souvent à la marge. L'étude expérimentale relatée a été conduite, de 1991 à 1995, dans le bassin cotonnier du Nord-Cameroun à la station de recherches zootechniques de Garoua. Cette étude a fait appel à une chaîne de mesures informatisées pour caractériser les capacités de travail des trois espèces animales attelées dans cette zone (zébu, âne et cheval) pour des efforts de traction variables et sous des conditions climatiques contrastées (saison sèche/saison pluvieuse). Les résultats obtenus montrent que les plages d'efficacité maximale au travail par espèce sont différentes, mais complémentaires : âne : force de traction < 30 kg; vitesse : 2,6-3,2 km/h; durée : 3-6 h/j.; cheval : 25-45 kg; 3,3 km/h; 4 h 30-6 h 30/j.; zébu : 25-75 kg; 2,4-2,9 km/h; 4 h 30-6 h 30/j. Le rendement énergétique net du travail de l'âne (26-29 %) est supérieur à celui du cheval (24-27 %) et du zébu (16-20 %). Il est montré qu'un animal effectuant un travail léger dépense au total beaucoup d'énergie pour sa locomotion, alors que pour un travail lourd, sa dépense énergétique est faible car l'effort, bien qu'intense, est de courte durée. Le référentiel mécanique proposé, bâti autour du concept d'adéquation animal-outil, est une aide à la décision pour l'équipement. Sa validité est critiquée et des améliorations sont proposées. Son utilisation en conditions paysannes permet d'apporter, par l'innovation technique, des solutions aux problèmes rencontrés que l'on peut ensuite affiner par le conseil de gestion