Recycled water - Good for parks, gardens and the environment

Abstract

The effects of fertilisers and recycled water (wastewater or effluent) on the performance of 20 grass species growing in 100 litre bags of sand were studied in Murrumba Downs in Pine Rivers Shire, just north of Brisbane in annual experiments over three years. From May to August 2001, control plots were fertilised every month, while unfertilised plots received no fertiliser. From April to August 2002, control plots were irrigated with potable water and fertilised, while effluent plots received no fertiliser. In the last pot experiment from December 2002 to June 2003, control plots were irrigated with potable water and fertilised, while effluent plots were fertilised only with nitrogen. A field experiment also compared plots with potable water and mixed fertilisers; plots with effluent and mixed fertilisers; and plots with effluent and only nitrogen. When adequately fertilised, the growth of the grasses was similar on potable water or effluent. Low concentrations of nitrogen reduced the growth of the effluent plots when they were dependent on the wastewater for their nutrients. In contrast, the effluent supplied large amounts of phosphorus, potassium, sulphur, calcium and magnesium that could be used by the plants. The salinity and sodium hazards in the effluent were low. There are significant benefits in the use of effluent for sporting clubs and the environment. The use of effluent represents savings in irrigation and fertiliser costs to turf managers, and reductions in the discharge of nitrogen and phosphorus to local waterways. Effluent is currently about 50% of the cost of potable water, with a saving of about $8,000 ha-1 each year in water costs for a typical sporting field. Recommendations are provided for the use of recycled water in parks and gardens.