Efficient use of water resources in sugar production; optimising the use of limited water under supplementary irrigation

Abstract

About 60% of sugar produced in Australia depends on irrigation. In some regions, production would be impossible without irrigation; in others, irrigation is used to supplement rainfall. It can improve production and reduce risks in the more variable rainfall environments. The whole subject of supplementary irrigation has taken on a new focus in recent years as termsof- trade for cane growers continue to deteriorate, and as pressure mounts for more efficient management of a scarce national resource. Best practice with limited water, however, depends on complex biophysical and economic factors as well as sensitive off-site impacts. From a biophysical point of view, questions arise as to the probability of achieving the desired irrigation responses in the various regions and seasons, and the extent to which this is affected by crop water requirements at various stages and by variety and soil type. From a management point of view, the questions concern source of the water, the amounts available, and the best crop type and block on which to apply it. Finally, from an economic point of view, the questions concern the interactions between the above factors and the size of the investment required, the likely price of cane, and the probability of achieving sustained profitability from the investment during its lifetime. The aim of this project, therefore, was to address this complexity by developing and applying a generic methodology for assessing the payoffs of supplementary irrigation, taking account of the above factors.