EVALUATION OF VARIOUS IRRIGATION SYSTEMS FOR HIGHEST ECONOMICAL YIELD AND OPTIMUM WATER USE FOR BANANAS

Two trials were established to determine the most suitable irrigation systems for Burgershall (cool subtropics) and Komatipoort (hot subtropics). Various irrigation systems (drip single line, drip double line, micro-sprinkler, pulsator and overhead floppy system (Komatipoort only) are being tested over three crop cycles. Irrigation scheduling is controlled by tensiometer and soil water potential (SWP). The drip and pulsator systems are scheduled to a constant SWP of 15 kPa and irrigated daily. The micro and overhead floppy systems are irrigated at SWP of 25 kPa, at intervals of between 3 to 4 days.

Results of the P cycle at Burgershall show little influence of irrigation system on plant development. While the micro system averaged highest bunch mass, drip systems tended to have shorter planting to harvest intervals. With 3% higher yields, the micro system used 29% more water than the drip systems.

At Komatipoort, drip single used 12% less water than drip double but yield was decreased by 7% (51 t/ha/year compared with 55 t/ha/year). Obviously, high evaporative demand could not be met by the reduced wetting pattern of the drip single, resulting in light water stress. Micro proved superior in Komatipoort, showing yields that averaged 8% higher than pulsator, and drip double and 17% higher than drip single. Overhead floppy did not show any advantage compared with the other systems tested. High rainfall and good rain distribution during the P cycle were probably responsible for this. Similar to Burgershall, 29% more water was used by the micro system in Komatipoort to produce an 8% higher yield.

Preliminary results show that although not achieving highest yields, drip systems gave high production and superior water use efficiency. Results of further crop cycles as well as a full economic analysis will be necessary before reliable recommendations can be made.