The effective management of acid sulfate soils is a major issue for many
coastal regions in Australia. Simulations were conducted to evaluate 4
different water management strategies that could be applied to agricultural
land on the south coast of New South Wales, Australia, to minimise acid
generation from acid sulfate soils. The water management strategies are
compared with the existing extensively drained situation which generates and
discharges large quantities of acidic pyrite oxidation products. The 4 water
management strategies include elevated drain water levels using a weir, 25 mm
irrigation on a 7- or 14-day cycle, and elevated drain water levels with
irrigation. All of these strategies were designed to minimise the generation
of acid by reducing the transport of oxygen to the sulfidic soil. Simulations
were conducted for weather and site conditions experienced during a 12-month
period starting in July 1997.
Model simulations showed that maintenance of elevated drain water levels using
a weir in the drain significantly reduced the amount of acid generated by
75% and 57%, at 10 and 90 m distance from the drain,
respectively, by comparison with the existing drained state. The addition of
25 mm irrigation on a 14-day cycle to the weir simulation reduced the
oxidation of pyrite by a further 1–2%. Application of irrigation
only on a 7-day cycle also reduced the acid generated by 89% and
94% at 10 and 90 m distance from the drain, respectively, by comparison
with the existing drained state. Irrigation on a 14-day cycle was not as
successful in reducing pyrite oxidation as either the 7-day irrigation or weir
strategies. Evaluation of the 4 water management options showed that
significant improvements can be made with respect to the amount of acid
generated by relatively simple and cost-effective land management practices.
Water Management Options for Rice Cultivation in a Temperate Area: A Multi-Objective Model to Explore Economic and Water Saving Results