| Long term investigations of the effect
of tillage practices on crop production at Wagga Wagga, NSW
Research Supervisor:
Professor Jim Pratley
Research Staff:
Mr David Thompson, Mr Darren Collins; Mr Jonathon Medway
Funding:
Farrer Centre
Duration:
1977 onwards
Project Summary:
In the 1970s and before, seedbed preparation comprised several workings with
cultivating implements. At the time, the oil crisis and
concerns about soil structure degradation prompted investigations into alternative methods of
seedbed preparation. The availability of
"knockdown" herbicides and subsequent availability of
post-emergent selective herbicides facilitated
development of these alternative methods.
In 1977 an investigation commenced to evaluate the effects of different tillage treatments on
crop production on a continuing basis. Treatments compared were conventional cultivation (at least
three workings pre-sowing), reduced cultivation
(one cultivation plus knockdown herbicide pre-sowing)
and direct drilling (no pre-sowing cultivation,
knockdown herbicide only). The comparisons were carried
out using large plots of 0.25 ha, organised in a randomised block design with three replications.
For the first 8 years the trial was sown to wheat
after which a rotation was imposed to improve the prospect of sustainability.
The outcomes of the experiment were:
• that grain yields from direct drilling were
never significantly worse than the other treatments
and significantly better in dry springs.
Experimental yields approached estimated water-limited yields
in most years;
• that weed populations were generally
greater where cultivation occurred, particularly
fumitory (Fumaria spp);
• that eyespot lodging had greater impact on
wheat in the conventional and reduced cultivaton treatments with minimal effect in direct
drilled treatments.
The outcomes of the investigations indicate that
direct drilling is a viable technique for continuous
crop production with agronomic advantages for weed
and disease control.
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