By Wikus Joubert, Manager, BGASA
South Africa is a country subjected to an erratic rainfall pattern and subsequent serious sporadic droughts with a detrimental effect on harvests. The only sensible way to combat these conditions is to cultivate crops under irrigation. Even in years of good precipitation irrigation is still a prerequisite to optimal production.
The regularity and quantity of expected rain for a given season is not the only factors to be considered when an irrigation system is planned. Other prevailing climatic conditions besides rain such as soil type and condition, the crop and its demand for water, water quality and other factors must also be accounted for. The viability of a new planting, and the sophistication of the irrigation system are determent by the solvency of the crop. The irrigation system decided upon must indeed add value to the production potential, and therefore the profitability of that specific crop.
The question is often asked by producers which irrigation system are the best suited for a crop, and there is no simple response to that question as already indicated by the variables described before. It may well vary between neigbouring farms, not even to mention deviations on the same farm. It is therefore essential that all the variables be considered in conjunction with irrigation expertise for every unique situation.
To assist producers in making the correct decision the BGASA has funded a research project to evaluate different irrigation systems for banana production and for water use efficiency. The trials were conducted at an optimal level of management and with good quality water.
Two similar trials were simultaneously run for this purpose, one at Komatipoort and the other at Burgershall research station. Five different systems being single line drip, double line drip, pulsators, micro jets and Floppy sprinklers were compared in the trials. The conclusions from the trials were as follows:
- The results accruing from the trials substantiated the differences between venues as discussed above, by finding that the water requirement for bananas in Komatipoort was actually 12% higher than in Burgershall. Temperature, the occurrence of wind, and soil types were main contributors towards this difference.
- It was furthermore established that the Floppy system in common with the single line drippers were the lowest consumers of water, with the micro’s the highest.
- The results further established relatively small differences in the production between the different systems, with micros the best for production but with the poorest water use efficiency. Water use efficiency is determent by the ratio between water use and production. This is an important issue when the available water supply is suspect, like in this current drought situation.
Of all the systems the Floppy sprinklers were the most water use efficient according to this trials.