Vs For Erosion Control On Flat Land

VETIVER GRASS SYSTEM FOR STRIP CROPPING Paul N. Truong1, Paul A. Dalton2 and Clive D. Knowles-Jackson3

1

Resource Management Institute, Department of Natural Resources, Indooroopilly, Queensland. 2 Agricultural Engineering, University of Southern Queensland, Toowoomba, Queensland. 3 Land Conservation, Department of Natural Resources, Oakey, Queensland.

Strip cropping layout is designed to spread flood water and reduce soil erosion on low gradient floodplains subject to deep overland flows. This practice is widely used on the Darling Downs and NW slopes of New South Wales. A sequence of crop, stubble and fallow strips of uniform width are arranged perpendicular to the flood flow direction. The aim is to spread flood waters laterally to reduce flow depth, velocity and consequently erosivity of flow.

Typical strip cropping layout on the floodplain of the Darling Downs.

An alternative to conventional strip cropping layout is the incorporation of Vetiver hedges with the following advantages:

A site at Jondaryan protected by 9 Vetiver hedges (totalling 6 000 m) at 90m intervals (equivalent to 5 strips).

A newly established hedge.

Î Î Î

greater flexibility to maximise opportunity cropping

Î

upto 30% increase in cropped land

Dense growth retards water flow and traps sediments.

Deep and extensive root system binds the soil and enhances drought tolerance.

Hedge hydraulic characteristics needed for layout design were determined by flume tests.

Stiff blades provide effective barrier to water flow.

more easily managed land more effective spreading of water Î in dry years Î in crops producing little stubble ( for example cotton, sunflower)

Crop protected by Vetiver hedge.

Flood of Nov. 95 (600mm depth).

Little sign of erosion in fallow strip.

Young sorghum crop protected from flood flow.

Sorghum crop undamaged by flood.