How to produce more biomass for DMC in Sub-saharian Africa: The case of Northern Cameroon

Ces photos présentent des exemples de rotation mais on peut encore en imaginer des dizaines d'autres basées sur les même principes

Faisabilité et adaptation au contexte, les systèmes/plantes retenus en 2006 et 2007 avec atouts et limites. Le bilan de la pré diffusion des SCV 2006 suit avec quelques premiers résultats de la diffusion des SCV en 2007 puis la vision de L'OPCC par rapport la diffusion des SCV.

1. Produire plus de paille pour couvrir le sol même si les animaux en mangent une partie 2. étouffer les mauvaises herbes entre les lignes de céréales 3. Améliorer le sol grâce aux racines des cultures et des plantes associées qui font comme un labour 4. Améliorer le sol grâce aux racines des plantes associées qui vont pourrir sur place.

2 objectifs pour cette étude : i Identifier et caractériser les espèces légumineuses locales puis évaluer l'effet des PLUM sur le Striga. Un grand nombre d'espèces locales possédant des potentiels variés pour l'amélioration d'un système de production. Certaines ont un effet contre le Striga. Ces plantes locales à usages multiples et d'autres méritent plus d'attention pour pouvoir les incorporer dans les parcelles de culture ou jachères pour une démarche vers l'amélioration de l'environnement au Nord Cameroun.

Fiches techniques pour Coton, Brachiaria ou légumineuse (Crotalaria retusa, niébé, dolique) en SCV avec recommandations pour semis, fumure, contrôle adventices et insectes

Diaporama sur les SCV au Cambodge: Historique, composante SCV du projet Hévéaculture familiale, 2 ensembles pédoclimatique: terres rouges basaltiques et hautes terrasses rizicoles avec leurs limitations actuelles et les nouveaux systèmes diversifiés proposés (pompes biologiques avant cultures, associations avec pâturage), et riz pluvial pour zone inondé avec diversification de cultures.

About 250 farmers have tried comparing cereal cultivation under direct seeding mulch-based cropping systems (DMC) against the traditional cropping practices from year 2001 to 2004. The on-farm tested systems include mixed cropping of a cereal (maize, sorghum, millet) and a cover crop (mucuna, brachiaria, crotalaria, cowpea, dolichos). These mixed cropping practices are done for the following objectives: 1) Produce aboveground biomass to build-up mulch for the following season's crop (mainly cotton). 2) Soil improvement through the physical and chemical (produce N) contribution of the associated plants. 3) Forage production. 4) Weed control. 5) Protect the soil surface against erosion and rain impact. 6) Produce consumable grains for man and animals. Up till present the tested plants meet the above objectives differentially and are adapted to the local agro climatic conditions of North Cameroon (rainfall from 700 to 1200 mm). Thus Brachiaria ruzisiensis produces aboveground biomass in quantities (4-5 t/ha even under mixed cropping) and quality (persisting as mulch for over one year after production). Further, it is very efficient in controlling Striga and is a good forage crop. However, it can impoverish the soils if its biomass is exported several times without any fertiliser supplements since it is not a nitrogen fixing plant. On the contrary Crotalaria retusa is a nitrogen fixing plant and therefore enriching the soils. This plant is less palatable to animals and therefore advantageous to farmers who cannot protect their farmland from pasturing animals in the dry season. It is equally very efficient in controlling weeds. Four years of experimentation has enabled us to produce practical recommendations in mixed cropping on the following : sowing date, crop type, tolerance to herbicides, competition with cereals, etc. This experimentation has also enabled us to see how the various plants tie with the above-mentioned objectives. On-going research work is on the following: 1) Diversifying the range of plant material available, focusing on local varieties. 2) Extending these cropping techniques to cover vertisols covering tens of thousands of hectares in North Cameroon. 3) Introducing these plants at the beginning and at the end of the cycle of the main crop in order to better use early and the late rains.

The present study was carried out in the cotton belt in the Far-North Province of Cameroon. It has been focused on the physical properties of soils under mulch-based cropping systems. The experimental design was drawn from one on Direct seeding Mulch-based Cropping system (DMC) trial location under a controlled conditions in the region of Kaéle (700-800 mm mean annual rainfall), and where a network of 20 farmers is carrying out on-farm trials in the region of Maroua (800 mm mean annual rainfall),. Plots under mulch-based cropping systems established 2, 3 or 4 years ago were compared against farmers' traditional plots under direct seeding without mulch or with tillage practice. These plots were cropped with sorghum or cotton. Using the gravimetric method it has been shown that the apparent density of soils on the upper horizons under DMC was lower compared to soils from the farmers' traditional cropping systems. Bulk density values lie between 1.2 g/cm3 to 1.5 g/cm3 against 1.6 g/cm3 to 1.7 g/cm3 for farmers' traditional control plots. These results are due to an increase in soil porosity induced probably by a higher soil biological activity. A better water infiltration was also obtained'under DMC against the farmers' traditional systems. These mean infiltration values were obtained using the double ring and «Beer can» methods, and lie between 0.9 to 5 mm min-1 for the mulch-based system against 0.6 to 1 mm min-1 for the farmers' traditional systems. This study shows that after a period of less than 3 years under DMC an improvement of the physical properties of the soil was clearly obtained, notably soil porosity and consequently soil water dynamics. This improvement affects the soil water availability and therefore water supply to the crops.

Brachiaria ruziziensis est une graminée très feuillue, stolonifère et pérenne (> 3 ans). Elle produit rapidement une forte biomasse (jusqu’à 15 t/ha en 3 mois). Son puissant système racinaire capable de mobiliser des éléments minéraux dans des sols difficiles (compactés, acides et à toxicité aluminique) lui confère une large adaptabilité dans le cadre des systèmes de culture en semis direct. Notamment, ses capacités de décompaction le placent comme un précédent idéal pour le riz pluvial.