Réactions et craintes des paysans liées à l'utilisation du pois mascate (Muca pruriens var. utilis)

Dans IDL-1387

Influence des dates de semis de Mucuna sur le rendement du maïs au Bénin

Dans IDL-1387

Evaluation of integrated crop management strategies employed to cope with Striga infestation in permanent land use systems in southern Benin

Striga hermonthica and S. gesnerioides pose serious threats to cereal and cowpea production, endangering peoples' livelihoods on the Abomey plateau, Benin. A 2-year joint experiment was undertaken with farmers in two hamlets to investigate the potential of managing sowing dates of cowpea, sorghum transplanting, and trap cropping as ways of increasing agricultural production and reducing Striga damage. Early sowing of cowpea failed due to dry spells. Late sowing reduced cowpea yield due to water deficiency at the end of the growing season. Transplanting sorghum seedlings raised in fertilised or Striga-free nurseries doubled or tripled cereal yield and substantially reduced S. hermonthica infestation compared to direct early-sown sorghum. Transplanting sorghum from plant hills to fill gaps was unsuccessful. Trap crops such as cowpea and groundnut increased subsequent maize yield. Trap cropping had only a small effect on S. hermonthica infestation. The very poor soils in Som central were a major constraint upon yield improvement to acceptable levels even after the introduction of the new crop (and Striga) management method

Lg Coda Variations in North-Central Iran

Ground motion records in north-central Iran have been used in order to obtain the Lg coda , using stack spectral ratio method. The lateral variations in 0 and its frequency dependence are estimated in the 0.3–7.0 Hz frequency range which led to =267(±32)×0.71(±0.14). The observed variations in quality factor show low values of 0 in western part of the study region where bounded by relatively high values in southern and northern parts. Since the seismicity of the study area is quite shallow the obtained results can be attributed to the upper 30 km of the crust. The Damavand volcano and its surrounding region also exhibit variations in the value of 0 which result in low and intermediate values of 0 in western and eastern parts, respectively. Current seismicity in Damavand is mostly confined to its southwestern part, whereas our results proved to possess low values of 0. In general, most of factor variations can be attributed to the lateral heterogeneity as well as the severity of the crustal velocity gradient, and as expected the north-central Iran is well inferred as a tectonically active region

Improving local technologies to manage speargrass (Imperata cylindrica) in southern Benin

Speargrass (Imperata cylindrica) is difficult to control in the tropics. Farmers allocate most of their time and labour to weeding speargrass. We investigated in a joint experiment concluded with farmers, how effectively grain legumes suppress speargrass, and the relationships between speargrass suppression, legume grain yield, and subsequent maize yield. Without management, speargrass shoots and rhizomes increased with 31 and 17% per month, respectively. The integration of deep ridging, deep hoe weeding and shading suppressed speargrass more effectively than farmers' practices. Creeping varieties of cowpea that produced most biomass were most successful in suppressing speargrass and in enhancing subsequent maize yields, but erect cowpea cultivars produced more grain. Farmers traded off cowpea yield against speargrass suppression to bridge the hungry gap. They preferred the erect cowpea cultivar wan. The need to forego a harvest and the fact that pigeonpea is not consumed in the area makes pigeonpea presently unsuitable for integration into the cropping system

Adoption of improved fallows in West Africa: lessons from Mucuna and Stylo case studies

Traditional shifting cultivation systems can no longer be sustained in West Africa because of rapid increases in human and livestock populations. Short-duration, improved fallows are among the alternative land-management strategies that have evolved. This paper reviews how velvetbean or mucuna (Mucuna pruriens) and stylo (Stylosanthes hamata and Stylosanthes guianensis) management systems were developed and disseminated in West Africa. Mucuna was first adopted by farmers in southwestern Benin between 1988 and 1992, and the number of testers of the innovation rose to 10,000 farmers throughout Benin by 1996. Suppression of spear grass (Imperata cylindrica) was perceived as the main benefit of mucuna fallows. The stylo technology was introduced in the late 1970s, and it was primarily targeted to livestock production in the subhumid monomodal rainfall zone. The uptake of stylo has been relatively slow and modest in West Africa in contrast to the faster rate of adoption of mucuna in southwestern Benin. Some of the contributory factors to the slower adoption of stylo than mucuna include rainfall regime, lack of motivation of livestock keepers, insecure land tenure, limited capability and facilities of extension staff, poor communication among scientists, and unsatisfactory establishment of the crop. Recommendations to increase the adoption of improved fallows include the use of a participatory approach in problem identification, expansion of the genetic base of cover crops for use in fallows, optimization of the multiple benefits of cover crops, management of the improved system, promotional strategies, and appropriate policies

The social construction of weeds: different reactions to an emergent problem by famers, officials and researchers

Rapid population increase in southern Benin has changed the prevailing system of shifting cultivation into one of more permanent land use. New herbaceous weeds exacerbated rural poverty through crop failure, higher labour inputs, rising costs of production and reduced availability of suitable land. We investigated how different actors reacted to the emergence of weeds, in terms of the construction of knowledge, labour practices and technology development. Weeds have become an important cause of rural poverty. Farmers have actively engaged in technology development and new labour practices have emerged. Officials early on did report weed problems, especially where export crops were concerned. Researchers have not translated the new weed problem into a research priority until very recently, resulting in limited and inappropriate weed management technologies. The challenge of the research of which this study is part is to optimize weed management, by combining emergent indigenous weed management practices with scientific knowledge