BIOSOLIDS FOR  GROWTH

 Sewage sludge or "biosolids" are boosting the growth of radiata pine plantations in the Wingello State Forest south of Sydney.  The thickened muddy solids derived from wastewater treatment are applied by tractor and spreader.  The CSIRO advised that  "biosolids act as a slow release fertilizer and provide useful nutrients over an extended period".  Until 1993, biosolids were dumped in the sea.  Today, 99% of the biosolids are recycled, mainly as fertilizer in agriculture and horticulture.  At present, less than 10% of production is applied to forests.  One application of biosolids of more than 1000kg/hectare produced in increase in annual tree growth of about 35%, which was sustained throughout the 3-year trial.  Nitrogen and phosphorus levels in the foliage increased by 20-50%, and higher levels of micronutrients were also measured.  With environmental protection becoming such a major issue to the consumer at large and the rapid rise of organics, biosolids is an area of horticulturalists should be considering.