Healthy Country   Sediment losses from Horticulture quantified

Sediment losses from Horticulture quantified
Sediment captured from in field runoff in a cultivated field 

Sediment captured from in field runoff in
a cultivated field. *Image supplied by
Department of Employment, Economic
Development and Innovation

A sediment monitoring trial was set up by Primary Industries and Fisheries  (Department of Employment, Economic Development and Innovation) in December 2009 to monitor soil losses from a horticultural field in the Lockyer Valley.  The trial is comparing soil loss from a field with half bare fallow (without cover) and the other half planted with a fast growing forage legume crop (Lablab).

Loss of soil from the two areas has been determined for two rainfall events (22mm and 30mm).  In the 22mm event, the bare fallow plot lost 1 tonne of soil per hectare whilst the section with the cover crop lost less that 0.1 tonne per hectare.  In the 30mm event, the bare fallow field lost 1.3 tonnes of soil per hectare and the cover crop recorded no soil loss.

The trial is continuing but the preliminary results indicate that maintaining cover in a field is a very effective way to minimise soil loss from cropping lands.  The Lablab was only just out of the ground at the time of the first (22mm) rainfall event yet it was sufficient to significantly reduce soil loss.

The demonstration has quantified the soil that can move off bare fallow fields during rainfall events.  In this case, the grower has in place sediment control measures such as a sediment sump, grassed drains and grassed buffer strips to filter sediment and minimise its movement off farm.

For further information, contact Julie O'Halloran, Primary Industries and Fisheries, Department of Employment, Economic Development and Innovation on Julie.O'Halloran@deedi.qld.gov.au