Waste turns barren paddocks into a success
The odour might be off-putting, but the use of biosoil, or biosolids – treated, dewatered human sewage sludge – has helped New South Wales grower Danny Flanery to vastly increase the productivity of his soils, doubling their organic carbon content over the past five years.
The soil restoration is part of an overall strategy to lift the fertility and productivity of his property ‘Boorowa Flats’, at Galong, NSW, after an aerial photograph a decade ago revealed a devastating picture of degraded paddocks, large salt outbreaks and bare, eroded creek gullies.
Danny runs a mixed cropping/livestock operation with his father John and their families. The Galong area is characterised by acidic (pH <4.8), weathered granite soils – predominantly red and brown clay loams and some lighter soils, low in native phosphorus and organic matter. Rising saline groundwater has also been recognised federally as an urgent threat to the region’s productivity.
Danny has received assistance through the Murrumbidgee Catchment Management Authority (CMA) for extensive tree planting, which has helped to address salinity and erosion issues. The Murrumbidgee CMA also sponsored his attendance at the 2008 Soil Science Australia Conference in Brisbane, where he was introduced to a range of new ideas for soil management, including the use of biosoil as a soil ameliorant.
Biosoil is cheaper than pig or poultry manure and is rich in nitrogen, phosphorus, trace elements and organic matter, which has allowed Danny to cut back on his fertiliser inputs. His organic carbon levels have increased from 1 to 1.5 per cent to 2.7 per cent on treated paddocks.
His crop yields have jumped from a low of 0.25 tonnes per hectare for wheat and 0.2t/ha for canola to 4.2t/ha and 2t/ha respectively. His wheat protein levels range from 14.9 to 15.7 per cent.
However, the use of biosoil is not without its issues: the smell plus required buffer zones around dwellings, towns, watercourses and storages. Biosoil can also only be applied once every five years over any given area. Danny applies lime in conjunction with the biosoil to address any potential local acidity issues, although this is not a NSW Environment Protection Authority requirement as biosoil is not acidic.
Danny buys large quantities of biosoil each year, applying it at rates of between 50 and 80t/ha to paddocks as they comes out of a pasture phase.“We run a rotation of canola/wheat/canola/wheat/canola/wheat undersown,” Danny’s agronomist Andrew Daley says. “If it is a strong paddock, we will keep it in crop and apply more biosoil in the sixth year.”