AFTER seeing the results of tillage trials on his own property, grower Dennis Kitto of 'Uralba' is convinced that reduced tillage is one of the best options for wheat cropping in the low-rainfall, flat landscapes typical of the West Wyalong area in the south of Central West NSW.
"Although we can get better yields from a traditional tillage approach, the costs are higher," says Mr Kitto.
"The bottom line is that you have to be economically viable and look after your soil. Reduced tillage seems to work in this area."
The trials have convinced Mr Kitto that the seedbed needs some mechanical preparation, and that's why reduced tillage seems to works best for the low slopes and heavy clay soils of the central and south-west districts of NSW.
Five tillage systems tria led
The trials, which were part of the Central Western Farming Systems project supported by NSW Agriculture and growers and the Federal Government through the GRDC, examined five tillage systems: traditional (or conventional) tillage; reduced tillage; no-till; stubble incorporation; and stubble retention (see box for definitions). Janz wheat was used in the trials on Mr Kitto's property.
According to NSW Agriculture agronomist Bob Thompson, the 20 per cent yield penalties suffered by wheat in stubble-retention and stubble-incorporated systems in some years surprised most growers, because they previously had nothing to compare their yields to.
"Disease problems, especially yellow leaf spot, ravaged the wheat grown under stubble-retention and stubbleincorporation systems in wet years, with a resulting loss in yield," says Mr Thompson.
Hard system for wheat on wheat?
In Mr Thompson's opinion, the disease factor alone is sufficient to avoid these two systems when sowing wheat on wheat in the West Wyalong area. Even so, problems with seeding and establishment in heavy soils with significant amounts of stubble had caused many local growers to abandon attempts at stubble retention. The trials also confirmed for Mr Kitto and many other growers that no-till was found to be less suitable for growing wheat in the West Wyalong area in drier years.
Reduced till and traditional tillage systems gave better outcomes under these conditions.
Match tillage to soils and rainfall
According to Mr Thompson, the explanation for the poor performance is that direct-drilling wheat seed into the heavy soils typical of the area impedes early root growth.
"In an area with an average of only 220 mOl of growing season rainfall, the delay in early crop growth can be devastating for yields," says Mr Thompson.
"In areas where the soil and spring rainfall conditions for crop growth are much more favourable, such as in northern NSW and in Queensland, growers don't see the yield penalty for no-till that we get here," he adds.
Mr Kitto says because it's flat and because of the soil types in the central and south-west districts of NSW, "as long as we retain some cover over a couple of summer months when there are a few storms, we seem to be able to control soil and wind erosion pretty well".
Mr Thompson now recommends that local growers aim for a reduced-tillage system for wheat - emphasising that these results are for wheat only.
Studies pending for canola and pulses
Work in the next three years will focus on assessing the various tillage systems for other crops such as canola and pulses.
"Just because it was disappointing for wheat does not mean it was disappointing for other crops," says Mr Thompson. "Conservation farming does not refer to a particular tillage system. It implies only that the tillage system employed in a particular paddock is matched to the capacity of the soils, slopes and climate, without degrading the soil resource."
Wheat grain yield from tillage system trials on 'Uralba' in the Central West of NSW
|Tillage System||Wheat yield (t/ha)|
Tillage systems trialed in Central Western Farming Systems trials at West Wyalong, NSW
- Traditional tillage - uses cultivation as the main method of weed control and soil preparation.
- Reduced tillage - weeds are controlled with herbicides, and One cultivation used to prepare seedbed.
- Stubble retention - the crop is planted into an unprepared, stubble-covered seedbed with no cultivations.
- No-till - the crop is planted directly into an unprepared seedbed after stubble is removed by grazing or burning.
- Stubble incorporation - crop residue is ploughed in and weeds controlled with herbicides.
Program 3.4.2 Contact: Mr Bob Thompson 08 8303 9353
North, South, West