laterals. A flexible dragline hose (20 or 25mm diameter) connects a tripod stand, mounted with a sprinkler, to the lateral. Portable laterals are moved once each stand has completed its positions. One hose and sprinkler can usually cover 3, 5 or 7 positions from a lateral. Historically, dragline systems have used impact sprinklers which, in comparison with pivot, micro and flood irrigation, are water-use inefficient and energyinefficient. Draglines are more likely to be selected than centre pivots because of unsuitable land shape or financial constraints. The cost per hectare of a centre pivot decreases exponentially with area irrigated, but for dragline and fixed/static systems, the cost per hectare is relatively constant.
www.farmersreviewafrica.com
Other advantages include: · Less labour required than for a quick-coupling system, usually one labourer per 15ha. · No need to switch off pumps when sprinklers are moved. · With permanent laterals, no pipes are moved, only the tripods and sprinklers. · Dragline hoses have a 5 or 10 year lifespan. · The system has the lowest cost of all sprinkler systems The success or failure of an irrigation system depends to a large extent on careful selection, thorough planning, accurate design and effective management.
[11]FARMERS REVIEW AFRICA
March - April 2016