Generally, smallholder irrigation schemes (SIS) in South Africa have performed poorly and have not delivered on their development objectives of increasing crop production and improving rural livelihoods. Limited knowledge of irrigated crop production among farmers has been identified as one of the constraints to improved crop productivity, but research that investigates the relationship between farmer practices and productivity is lacking. A monitoring study was therefore conducted at the Zanyokwe Irrigation Scheme (ZIS) in the Eastern Cape to identify cropping systems and management practices used by farmers and to determine how these were related to performance. Evidence from 2 case studies showed that water management limited crop productivity. Irrigation application and system efficiencies were below the norm and irrigation scheduling did not take crop type and growth stage into account. Monitoring of 20 farmers over a 3-yr period showed that cropping intensity averaged only 48% and that the yields of the 2 main summer crops, grain maize (Zea mays L.) and butternut (Cucurbita moschata) averaged only 2.4 and 6.0 t•ha-1 , respectively. In addition to poor water management, other main constraints to crop productivity were inadequate weed and fertiliser management and low plant populations. The results indicated that a lack of basic technical skills pertaining to irrigated crop production among farmers was a possible cause of inadequate management. In this regard, it is expected that farmers could benefit from 'back to basics' training programmes in the areas of crop and irrigation water management. Research needs to focus on labour-saving production technologies, establishing farm-specific fertiliser recommendations, the identification and use of affordable sources of nutrients, as well as strategies to improve plant population in maize by preventing bird damage to newly-planted stands.
The adoption of a new irrigation scheduling tool by irrigators in South Africa was evaluated while it was still in prototype form. A wetting front detector (WFD) is a funnel-shaped device, buried in the crop root zone, which provides a mechanical or electronic signal to the irrigator when a wetting front moves past it. There was a survey of 54 irrigators or their advisors, who participated voluntarily by evaluating the tool under their own conditions. The survey showed that all participants perceived the device as simple and intuitive, and based on their own experience, 82% believed it conferred a relative advantage over what they were doing. The successful deployment of WFDs was highly dependent on matching the placement depths to the irrigation method and strategy. This required the irrigators to combine their own experiential learning with the response from the WFDs. The WFD showed promise as an irrigation scheduling aid, but requires the meeting of scientific and local knowledge, or a participatory research and extension approach, to reach its full potential. Copyright
RÉ SUMÉNous avons évalué l'adoption d'un nouvel outil de pilotage de l'irrigation par les producteurs en Afrique de Sud alors qu'il était encore au stade de prototype. Le Détecteur de Front d'Humectation (wetting front detector, ou WFD) est un dispositif en forme d'entonnoir, enterré dans la zone de croissance des racines, qui fournit un signal mécanique ou électronique quand un front d'humectation l'atteint. 54 producteurs ou leurs conseillers ont été inclus dans l'étude. Ils ont tous participé volontairement en évaluant l'outil sous leurs propres conditions. L'enquête montre que tous les participants ont considéré le dispositif comme simple et intuitif; 82% pensent qu'il apporte un bénéfice par rapport à leur pratique antérieure. La réussite dans le déploiement du Détecteur de Front d'Humectation (WFD) dépend fortement de la bonne adaptation de la profondeur de placement à la stratégie d'irrigation. Cela exige de la part des irrigants de confronter les connaissances tirées de leur propre expérience avec les résultats provenant du WFD. Nos concluons que le WFD est prometteur en tant qu'aide au pilotage de l'irrigation, mais requiert la conjonction des savoirs scientifique et local ainsi qu'une approche participative de recherche et vulgarisation pour réaliser tout son potentiel.
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