Development of Visual Extension Material for a Striga Control Programme in Northern Ghana through Action Research.
Abstract In the last two decades, research has developed techniques to control the parasitic weed Striga sp. (Scrophulariaceae), one of the worst pests in the West African Sahel. Yet, some of the control measures are economically not viable, at least not in the short-run, others cure part of the problem only, while some require changes of the entire farming system. The complexity of the problem demands an integrated control approach with solutions that are flexible enough to match the diversity and variability of the farming systems. A better understanding of the parasite's biology by farmers will encourage them to appreciate the current complex and time-consuming Striga control measures. Such an approach calls for close collaboration between researchers, extensionists and farmers. Through action research, a picture supported group extension programme was developed, which was characterised by a shift from a teaching-centred to a learner-centred extension approach in Northern Ghana. The cost for developing...
Knowledge transfer in the field: Solving crop residue problems in Niger
A major recurrent problem of agronomic research is whether its results can be transformed into recommendations relevant to the livelihood of the intended beneficiaries, the small farmers—and if they can, then how. This problem is illuminated by research on mulching with millet crop residues, and by the translation of the results into agricultural extension in Niger, West Africa. Comparisons of different experiments with identical crop residue applications, conducted in the same year and at the same research station but implemented on different fields and managed by different researchers, showed high heterogeneity in their outcome. In addition, farmers have multiple uses for crop residues, which greatly complicates the formulation and transfer of research recommendations. This discussion is examined from agronomic, economic, and extension viewpoints. The development of adapted innovations for farming systems in Niger requires that the current agronomic research be reconsidered, with a move toward greater participation of farmers. Alternatives to the dominant transfer of technology concept are discussed.
Analysis of a coaxial-to-waveguide adaptor including a discended probe and a tuning post
A field matching analysis of a coaxial-to-waveguide adaptor incorporating a disc-ended probe and a tuning post is presented. In this analysis, the tuning post is considered as a short-circuited second probe. A computer algorithm for calculating the input impedance of this structure is developed. This algorithm is used to investigate and improve the operation of a commercially available coaxial-to-waveguide adaptor. >