Key points
- An MPI SFF project, Don’t Muddy the Water, was set up to provide defensible, robust figures on the effectiveness of key erosion and sediment control measures on cultivated land.
- Trials to date have looked at retention pond size and the effectiveness of grass buffer strips.
- Run-off from cultivated land is three times less than from construction sites, so retention ponds on farms can be proportionally smaller than those on constructions sites.
- Both the small and large sediment ponds captured 100% of the eroded bedload (heavy aggregates).
- Overall, the large pond captured 99.9% of all incoming sediment (bedload and suspended) and the small pond captured 98.0% of sediment.
- The rate of erosion from predominantly flat paddocks (<3⁰) is very low.
- On steeper slopes (>10⁰) during high frequency small rainfall events no sediment was transported past the grass buffer strips.
- Vegetative buffers are more effective when paddocks are levelled to minimise ponding and channelling.
- Results will support growers, and inform national and regional policy development on soil and water quality management.