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In West Africa, long and complex livestock value chains connect producers mostly in the Sahel with consumption basins in urban areas and the coast. Regional livestock trade is highly informal and, despite recent efforts to understand animal movement patterns in the region, remains largely unrecorded. Using CILSS' database on intraregional livestock trade, we built yearly and overall weighted networks of animal movements between markets. We mapped and characterized the trade networks, identified market communities, key markets and their roles. Additionally, we compared the observed network properties with null-model generated ensembles. Most movements corresponded to cattle, were made by vehicle, and originated in Burkina Faso. We found that live animals in the central and eastern trade basins flow through well-defined, long distance trade corridors where markets tend to trade in a disassortive way with others in their proximity. Modularity-based communities indicated that both national and cross-border trade groups exist. The network's degree and link distributions followed a log-normal or a power-law distribution, and key markets located primarily in urban centers and near borders serve as hubs that give peripheral markets access to the regional network. The null model ensembles could not reproduce the observed higher-level properties, particularly the propinquity and highly negative assortativity, suggesting that other possibly spatial factors shape the structure of regional live animal trade. Our findings support eliminating cross-border impediments and improving the condition of the regional road network, which limit intraregional trade of and contribute to the high prices of food products in West Africa. Although with limitations, our study sheds light on the abstruse structure of regional livestock trade, and the role of trade communities and markets in West Africa.

Maize (Zea mays)-mucuna (Mucuna pruriens) systems have been promoted to the smallholder farmers of the Los Tuxtlas region of southeastern Veracruz, Mexico. To determine on-farm performance, an agronomic assessment was conducted in 1995-97 replicating farmer conditions in four fields. Treatments were firstand second-season maize with first-season mucuna (system Zm-Mp/Zm), first-season maize with first-and second-season mucuna (system Zm-Mp/Mp), second-season maize following first-season mucuna (system Mp/Zm), and first-and second-season maize, no mucuna control. Data on mucuna biomass amount and quality as well as maize yield, yield components, and nutrient status were collected. Highest mucuna biomass was obtained in system Mp/Zm (leaf-stem-mulch biomass in 1996/97, 7.34 t ha −1 , 147 kg ha −1 N), followed by systems Zm-Mp/Mp (5.06 t ha −1 , 101 kg N ha −1 ) and Zm-Mp/Zm (2.75 t ha −1 , 50 kg N ha −1 ). Second-season maize yield was increased over that of the control by 45-58 % (0.15-0.23 t ha −1 ) in system Zm-Mp/Zm and by 118 % (0.60 t ha −1 ) in system Mp/Zm. Mucuna did not increase first-season maize yield. Climatic constraints make second-season maize production risky and yield increases due to mucuna are low in absolute terms, perhaps not offsetting labour costs (systems Zm-Mp/Zm and Mp/Zm) or loss of first-season maize (Mp/Zm).

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Despite interest in mucuna (Mucuna pruriens) as a green manure/cover crop, biomass production of its accessions has been poorly quantified, including in the Los Tuxtlas region of Veracruz, Mexico where smallholders have used maize (Zea mays)-mucuna systems increasingly since 1991. This on-farm research compared the biomass production of three mucuna varieties (white-, mottled-, and black seeded) in a rotational maize-mucuna system. Mucuna was sole-cropped during the first season (on eleven and five fields in 1996 and 1997 respectively), and its impact on the second-season maize yield was measured (on seven fields in 1996). White and mottled varieties produced equal biomass (7.92 and 6.74 t ha −1 in 1996 and 1997 respectively), and more than the black variety (6.85 and 4.90 t ha −1 in 1996 and 1997 respectively). Mucuna increased 1996/97 second-season maize grain yields by 50 % (from 0.97 to 1.46 t ha −1 ). Plots previously cropped with white and mottled varieties produced greater maize yield (1.55 t ha −1 ) than did black-variety plots (1.29 t ha −1 ). The research confirmed the higher productivity of the white and mottled varieties and the potential of the rotational system. Allocating the more desirable first-season growth period to mucuna and the riskier second season to maize is problematic, but the system may have potential in the region as a short-term fallow that permits second-season maize production. I N T RO D U C T I O NIn the past decade, Mucuna pruriens has been the most promoted and researched green manure/cover crop. In spite of this, the biomass production of different mucuna accessions has been poorly quantified. Lack of systematic trials in contrasting environments, and the uncertain taxonomy of mucuna (Duke, 1981) have contributed to this situation. Evaluation of mucuna accessions is imperative, however, because of the role biomass production plays in determining benefits (soil and yield improvement, as well as weed suppression) derived from the incorporation of mucuna in the farming system .The taxonomy of the genus Mucuna is confused (Duke, 1981;Carsky et al., 1998). The genus is at times referred to as Stizolobium, and there has been disagreement over the correct categorization of accessions within the genus. In recent decades,

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Sahelian livestock systems, an indelible feature of its landscapes and significant contributor to its economies, are under significant pressures to change. Whereas high predicted demand increases for livestock products offer great prospects for income growth, expansion of croplands and settlements as well as climate change will likely negatively impact Sahelian producers. It is clear that for Sahel to respond to livestock market opportunities, changes in traditional trade and production practices are needed, in particular to improve reach of market signals to producers, reduce the high transaction costs, and improve productivity. The Sahelian markets have to date shown continued capacity to supply growing Sahelian and regional markets, and in fact the changes, are already evident. These include expansion and diversification of trader networks, changing procurement patterns, agricultural expansion, and increased use of supplemental feeds, among others. These changes are certain to further evolve.