Leyburn-Millmerran, Queensland, AU

Conventional to Conservation

Random wheel traffic from tractors, sprayers, and harvesters – associated with conventional cultivation practices – is highly destructive to soil structure and organic matter. On the Darling Downs region of Australia, such farming practices over many decades caused greatly compacted subsoils and contributed to declining crop productivity over time.

Such was the history of these farms up to 1995 when Controlled Traffic Farming plus No-Till (CTF+NT) soil and crop management were rigorously adopted. All cropping fields were then effectively partitioned into two areas: ‘traffic-zones’ (12-15% of field area) for permanent confinement of all wheel tracks, and ‘cropping zones’ (85-88%) for crop rooting only with no machinery wheel-tracks to cause compaction.

CTF+NT management and increased crop rotation diversity greatly enhanced the efficiency with which the highly variable and limited rainfall could be converted to harvested crop. Typically, a two-fold improvement could be achieved here.

Challenges Resolved

Solving soil erosion and compaction within very tight budgetary constraints.

Conventional cultivation was the ‘norm’ across these farms up to the mid-1990s—conversion to CTF+NT was subsequently undertaken within very tight budgetary constraints. Located on the Condamine River flood-plain it was logical to move to NT to minimise future soil erosion damage and to combine this practice with CTF management. The real challenge lay in implementing this conversion by cost-effectively modifying existing machinery and equipment originally designed for conventional cultivation. Also, the requirement to be able to move between irrigation and rainfed cropping regimes with different optimal wheel-centres for CTF.

Cropping system required diversification.

The cropping system, primarily focussed on cereals and cotton, was diversified to include grain legumes – chickpeas, mungbeans, soybeans. The myriad benefits of diverse crop rotations that include a strong legume component are well-recognised—breaks in cycles of various weeds, pests and diseases; fixation of “free” atmospheric nitrogen for the growing legume and subsequent crop/s; alternative revenue stream/s; differences in crop calendar/s that often improve overall timing efficiencies; enhanced soil micro-biology.