Fencing and revegetation of riverbanks are commonly adopted practices for protection of waterways from on-farm management practices. These buffered zones may perform a variety of functions including slowing the movement of water and trapping sediment and nutrients. Surface soil properties may contribute to the zone's ability to reduce nutrient loss. To this end a study is being conducted to identify changes in selected soil properties following revegetation of riparian zones on dairy farms in the South Gippsland region of Victoria, Australia. This study has involved comparison of nutrients, organic matter, cation exchange capacity and total organic carbon for fenced riparian sites that are cleared, revegetated for different periods and remnant vegetation.

Total phosphorus and nitrogen were also measured in soil by ion chromatography after microwave digestion with hydrogen peroxide. The humic fraction of organic matter was extracted using a sodium pyrophosphate/sodium hydroxide extraction method. The resulting humic acid was analysed by 13C solid state NMR and pyrolysis GC-MS. Exchangeable cations were analysed by ICP-OES on ammonium chloride extracts. Total organic carbon was determined by a wet oxidation method and measured by UV-Vis spectroscopy. A further comparison was made with the soil solution obtained from these sites.

This paper will present a detailed analysis of the results of this study, highlighting the differences between sites of different vegetation age, with a particular emphasis on the relationship between soil organic matter and nutrient retention.