In the high rainfall zone in south-west Victoria (HRZ >550mm/year), broad-acre raised beds are being rapidly adopted by growers for grain production. Raised beds have proven to increase yields and reduce risks associated with grain cropping due to the reduction in waterlogging and controlled traffic contributing to improvements in soil structure. In 2003, over 30,000 hectares of raised beds were under crop in the region.

An experiment was conducted to investigate the impact of raised bed grain crops on the quantity and quality of runoff water compared with conventional grain crops grown without raised beds and pastures. The 2001 season was characterised by above-average rainfall over the growing season, resulting in seven significant runoff events from all plots. Results show that the intensity and length of the rainfall event and the timing of rainfall during the season is a significant contributor to differences in runoff volumes between treatments. During a storm in April 2001, the raised beds released more runoff than the conventionally-cropped and pasture plots. However, there was negligible difference between treatments during lower intensity rainfall events over the winter that are more typical of winter rainfall patterns in southern Australia. Total phosphorus and total nitrogen concentrations for all runoff events were well above levels recommended as satisfactory for Victoria's inland waters. Phosphorous in runoff waters was predominantly in a dissolved form, suggesting that current nutrient management strategies based on physically trapping phosphorus attached to sediment (ie grassed waterways and buffer strips) are unlikely to be successful.