Placer le renforcement des capacités au coeur des processus des CSLP ?

La démarche consiste à construire de manière raisonnée des plans nationaux de renforcement de capacités en réponse à l'identification préalable des insuffisances constatées dans le processus CSLP (conditions d'élaboration des documents et contenu de ceux-ci); ce travail de formulation de plans de renforcement à l'échelle nationale est confié à deux experts nationaux dans 5 des 6 pays (Burkina Faso, Cameroun, Mali, Niger et Sénégal) ayant fait l'objet d'une étude pilotée par le REPA7, sous la coordination générale de la Plate-forme pour le développement rural en Afrique de l'ouest et du centre. Chaque binôme comprend un expert en ingénierie de la formation adossé à une institution nationale ou régionale de formation et un membre du Pôle de formateurs en politique agricole. (Résumé d'auteur

Microbial quality of commercial biofertilizers to increase nutrient use efficiency and crop productivity. O-P18

Commercial agricultural inoculants are increasingly being produced and sold in the market worldwide, and are claimed to have a major impact on increasing crop productivity. The main objective of this research was to characterize and assess the microbial content of biofertilizers obtained from different countries in order to verify whether they fulfill the claims of the manufacturers. The proliferation of the underperforming inoculants can thereafter be prevented, and value can be added to effective products. The microorganisms contained in the commercial inoculants were isolated, purified, and identified by partial sequencing of the 16S rDNA. Results showed that the majority (about 64%) of the products contained one or several strains of contaminants and only 37% of the products could be considered as pure. Forty percent of the tested products did not contain any of the claimed strains but only contaminants and several potential human pathogens were found. Rhizobial products were generally of better quality than the other PGPR-based products. Results highlight the need for better quality control systems to ensure efficacious products reach the end users. (Texte intégral

Collecting symbiotic bacteria and fungi

Soil is the habitat of an array of microorganisms in all three taxonomic domains. Because many species of soil microorganisms are still unknown or non-described, the assessment of microbial diversity, especially the symbiotic bacteria and fungi is not feasible undertaking. In designing field sampling to collect symbiotic microorganisms, the challenge is to select a subset of the soil biota that adequately reflects the anticipated taxonomic spectrum, and which at the same time includes all the symbiotic microorganisms considered important. Designing a successful, practical sampling scheme is an art. In this chapter, we tried to provide a guideline to make it correctly ensuring the representative of all the indigenous symbiotic bacteria and fungi naturally present in the soils of sampled sites. As the majority of the microorganisms, including the symbiotic ones, are found in the upper 20cm of the soil profile, the main investigations have to be done on topsoil even if it doesn't mean that microorganisms are not naturally present in deeper layers. Once the samples have been harvested, it is important to be cautious and store them nicely for further microbial analysis. Otherwise the risk to lose them or to get only contaminants after streaking is pretty high. This chapter describes some protocols and methodologies with practical and simple recommendations easily repeatable by people who have interest to make such laboratory work. We tried to raise the main steps ensuring the success of the establishment of the collection of symbiotic bacteria and fungi coming from all around the world. (Résumé d'auteur

Combined microbial inoculations as a promising approach to enhance promiscuous soybean nodulation and nitrogen content in Sudan Savana

Applications of microbial inoculants and reduced amount of inorganic fertilizers could lead to low - input agriculture and sustain smallholders' crops production. In this study, the effect of promiscuous soybean inocula tion with combined microbial inoculants was evaluated during harmattan season under furrow irrigation. Rhizobial inoculants and urea on one hand, and fungal inoculants and triple superphosphate (TSP) on the other hand, were considered as nitrogen (N) and p hosphorus (P) sources, respectively. The soil was sandy loam and slightly alkaline. Significant effect from rhizobial inoculants was observed on nodule dry weight. As well, the interaction between N and P source had significant effect on %Ndfa. The interac tion between 1495MAR and TSP induced the highest %Ndfa. The dual inoculation of 1495MAR and Rhizatech induced relatively high shoot N content. This study showed TGx soybean responded to rhizobial inoculation in Nigeria Sudan savanna. It showed that biofert ilizers could effectively increase soybean yield under furrow irrigation. It also suggested that microbial inoculants could perform during harmattan season. Furthermore, the study showed that selective interactions occur between rhizobial strains and funga l inoculants for soybean development. (Résumé d'auteur

Occurrence, distribution and genetic diversity of soil Phosphate Solubilizing Bacteria in soils of different chemical characteristics in Kenya

Phosphorus (P) availability in many soils is limited by high fixation and precipitation reactions, rendering it inaccessible for plant uptake. The ability to convert insoluble forms of P to an accessible form is an important trait in plant growth-promoting bacteria. The use of phosphate solubilizing bacteria (PSB) as inoculants has potential to increase plant P uptake and yield. Isolation of bacterial strains exhibiting high ability to solubilize insoluble P from soil and rock phosphate is therefore a matter of significant interest with practical applicability. Unfortunately this had never been done in Kenyan soils whereas natural P sources are available locally such as Minjingu phosphate rock from Tanzania. This study focused on the assessment of the native populations of PSB in thirteen Kenyan soils from five agro-ecological zones through their isolation, selection, molecular characterization and identification (sequencing of 16S rRNA gene). The occurrence and diversity of phosphate solubilizing microorganisms was investigated in cultivated land from thirteen sites. Air dried soil samples were serially diluted and plated in the National Botanical Research in Phosphate media (NBRIP). The results showed higher diversity of phosphate solubilizing fungi than PSB in low (Central, Nyanza, Trans Nzoia and Kisii) and high pH soils (Coast). The soils with a high PSB population had a near neutral soil pH (pH 5.8-6.8). Restriction fragment length polymorphism analysis revealed that the strains belonged to atleast 20 interspacer group (IGS) profiles. IGS profile II had the highest dominance among all the soils accounting for 56% dominance, and belonged mainly to Bacillus megaterium. There were 130 isolates which have been identified to genus and species level. The isolated microorganisms with phosphate solubilizing ability were either Bacillus sp., B. megaterium, Bacillus amyloliquefaciens, Paenibacillus sp. or Arthrobacter sp. Further studies on the assessment of the P solubilizing capacities of such PSB and on the interaction of the effective strains with crops are ongoing and should give us some relevant results on the potential of PSB to improve cereal and legume yields in Kenya. (Texte intégral

Do legume-based intercrops improve soil fauna and soil microbial diversity? Example of the cowpea-cassava intercropping system in Northern Vietnam (Yen Bai Province)

Industrial agriculture has allowed food safety through the crop homogenization and the massive use of pesticides and chemicalfertilizers. This intensive agriculture has positively influenced the crop productivity but has also negatively affected the environment with direct consequences on soil health and productivity. The importance of the micro and macro organisms in the sustainability of soil fertility is widely recognized. Soil fauna represents 23% of the global fauna and contributes to most of the ecosystem services such as porosity, soil aggregation, control of the microbial activity and plant protection against pests and diseases. To mitigate the collateral effects of intensive agriculture on soil productivity in South East Asia, agro-ecological practices are currently promoted, including the use of legumes in intercropping systems. We studied the effect of the intercropping system cassava-cowpea (Vigna unguiculata L.) on the soil biotic compartment in Yen Bai province, a mountainous region in the North of Vietnam. Intercropping resulted in the increase of macro fauna richness and evenness. Intercropping system also significantly enhanced both diversity and abundance of soil micro fauna. The high throughput sequencing analysis of the microbial community showed that bacterial communities' abundance and richness were significantly higher in intercropping system than in mono-cropping fields. However, intercropping did not significantly affect the fungal communities and the soil parameters including pH and organic matter. Our results highlight the importance of the promotion of agro ecological practices such as legume intercropping systems in the Highlands in Northern Vietnam where the sustainability of the ecosystem is very fragile