HR: 1330h
AN: H43B-04    [Abstracts]
TI: Novel Soil Amendment Technology for Minimising Nutrient Losses From Pastures for the Protection of Water Bodies
AU: * Chittleborough, D J
EM: David.Chittleborough@adelaide.edu.au
AF: University of Adelaide, South Australia, 5005 Australia
AU: Churchman, J
EM: Jock.Churchman@adelaide.edu.au
AF: University of Adelaide, South Australia, 5005 Australia
AB: The inevitable loss of P and DOC in runoff from pastures into water courses and water bodies poses a major environmental problem for industries such as dairy. We report a study of a novel approach to amending soils in dairy pastures. It is a test of the applicability to the field of the results of laboratory work that had shown that addition to soils of a water soluble polymer (Poly-DADMAC) - widely used as a coagulant in drinking water treatment - considerably enhanced the uptake by soils of anions, including phosphate. Its successful application in the field promises to provide a safe, easily-applied and relatively low-cost chemical as an soil amendment to restrain P and DOC in the soil against their loss downslope in runoff. Using a rainfall simulator to generate runoff, we show that most (on average >70%) of both the P and DOC that is lost from untreated pastures can be retained in the soil. It is only necessary to treat a buffer strip comprising 10% of the whole area in order to retain most of the P and DOC at a cost for polymer for one treatment of between $200 and $400/hectare of pasture. Whereas the effectiveness of the polymer treatment diminishes with time and was minimal after 85 days of treatment, the seasonality of rainfall in Southern Australia, where the research was conducted, means that most of the total year's losses of P and DOC can be restrained by one well-timed application in a normal year. Further application may be necessary in a wet year, but this aspect requires further research. When rainfall was exceptionally heavy, losses of P could not be contained by the treatment, although it remained effective in restraining DOC. The treatment did not enhance erosion and erosion losses could be decreased relative to untreated controls with low additions of polymer.
DE: 1806 Chemistry of fresh water
DE: 1860 Runoff and streamflow
DE: 1871 Surface water quality
SC: Hydrology [H]
MN: 2005 Joint Assembly