AN AUDIT OF FARMING AND FALLOW MANAGEMENT SYSTEMS
IN SOUTH QUEENSLAND
C. Knowles-Jackson
Queensland Department of Primary Industries, PO Box 199, Oakey, Qld 4401

The maintenance of soil productivity through protection against erosion and promotion of increased infiltration of rainfall by maintaining ground cover, either stubble or growing material, are major desirable outcomes of QDPI extension strategy related to cropping land management. Inappropriate farming techniques have caused a rundown in soil fertility and structure in high quality agricultural cropping lands of the Darling Downs, Queensland. In recent years, QDPI extension strategies have been aimed at promoting conservation cropping techniques such as retaining stubble, reduced (and zero) tillage and crop rotations. The stubble and crop cover survey was initiated to monitor the adoption of these techniques.

METHODOLOGY OF STUBBLE SURVEY

Approximately 1,000 sites are being assessed twice a year to determine stubble levels, tillage and cropping practices. The sites were randomly selected from cropping lands within the survey area in southern Queensland.

Information gathered at each survey site includes:

Soil Type

Land Slope

Land Use

Bank Space

Stubble Cover (Dead Plant)

Canopy Cover

Roughness (1-5)

Fallow Gradient (0-90°)

Surface Management

Surface Hardness (1-3)

Cracking (0-3)

%

Type

Weeds

Crop

Total %

%

Type

%

Type

RESULTS

Stubble cover for the first five years of the survey in the Oakey District of south Queensland has been estimated to be around 16% in summer and 15% in winter. These low figures reflect the severity of the current drought which has persisted for three years.

DISCUSSION

This survey is the first objective assessment of its kind carried out in south Queensland and will be a valuable indicator of the adoption levels of various Conservation Farming strategies within the area. The results to date have been used to alert landholders to the present low levels of stubble and to the real possibility of serious soil erosion occurring on their properties in the event of heavy rainfall. To achieve sustained economic productivity a minimum of 30% stubble cover at the point when the next crop is sown has been set as a target. To achieve this target by the end of the decade, clients will have to increase their understanding of the benefits of stubble and principally its effects on water infiltration and erosion control and economics of crop production.