Evaluating seeding systems in the Mallee by Cathy Nicoll

Grower Allen Buckley and researcher Jack Desbiolles.

After only two years of trials, an evaluation of seeding system technologies in the Mallee Sustainable Farming Project has shown growers in that region how their choice of seeding systems can affect the response of direct-drilled crops.

Machinery and know-how are two major barriers for growers thinking of moving to no-till. The trials conducted jointly by farmers, university and CSIRO scientists are testing a wide range of tine and disc-based seeding systems on properties in the northern Mallee districts of NSW, South Australia and Victoria.

"We are investigating the effects of deep soil disturbance and various seed/fertiliser placement configurations on the dynamics of the cropping systems, such as plant responses, weeds and root disease issues," explained Jack Desbiolles of the Agricultural Machinery Research and Design Centre, University of South Australia.

He said there is no aim to promote any particular brand name of seeding machinery, but rather to look in a scientific manner at the ways in which the machinery interacts with the soil. (See illustrations this page of different soil disturbance levels by seeding systems and examples of seed placement configurations.)

Big differences in growth

So far the trials have shown that early crop growth can be affected by as much as 50 per cent by different furrow environments, seed-placement configurations, and availability of fertiliser in the root zone. However the extent to which this early growth is carried through to grain yield is strongly dependent on seasonal factors.

"In this research we have measured 0.2-0.4 t/ha yield variation due to technology only. This is significant when compared to average crop yields at those sites of 1.4-2.2 t/ha," says Dr Desbiolles. (See table of wheat yield related to soil disturbance and seed placement, below.)

At Werrimull, for example, a shallow tillage depth of 90-95 mm with a knife-opener, creating only a low level of soil disturbance, produced a yield of 2.1 t/ha. This was significantly lower than the 2.3 t/ha obtained from a deeper tillage of 120-125 mm with the same opener. The same trend was observed with the 65 mm winged-point opener.

Deeper tillage is likely to have promoted rapid and effective development of the root system, with positive effects on early plant access to moisture and nutrients at depth.

According to Dr Desbiolles these early trends need to be assessed in the longer term to determine their real economic impact on farming in the Mallee. For example, he expects the effect of seeding-system technology to slowly evolve over time as soil health gradually improves under no-till farming.

For Victorian grower Tony Robbins of 'Bechari', who is close to the Werrimull trial site in the Victorian Mallee, no-till is worth a try just for environmental benefits, such as reduced wind erosion. The trials have already convinced him that there is neither a yield nor an economic advantage of conventional systems over no-till.

Trails opened a few eyes

The research has opened our eyes a fair bit. The results in all of the trials are extremely good compared to district practice in terms of economics and yield, and growers here are now thinking more about no-till and the types of machinery they are likely to need," says Mr Robbins.

"These trials provide an independent assessment of a range of commercial seeding machinery and to what extent they affect the longer-term performance of direct-drilled crops in the Mallee. We now have the support of more than 20 seeding equipment manufacturers and importers to help us achieve it," says Dr Desbiolles.

Grower Allen Buckley, of 'Glenrae' near Waikerie in South Australia, is host to one of the trial sites. He says it's the longer-term results that will be most interesting to him.

"I've already bought some new machinery, so now I'm interested in looking at the implications of trying wider row spacings to raise yield. What the trials are saying to me is that we need to look at the seeding rates and row spacings that will give us a very good yield in a veiy good season, and a good yield in an average season," says Mr Buckley.

About risk management

Mr Buckley says it is about more than high yields, it is also about risk management. The results of the trials give some insight on how to maintain high yields and get the benefits of less soil erosion and weed-seed disturbance from reduced-till farming systems.

The Mallee Sustainable Farming Project hopes to package the trial information in terms of farming systems that will work best in different parts of the Mallee. Growers now have the opportunity to see how well continuous cropping rotations can work, the sort of machinery needed, and the likely performance in their local area and soils.

Details of the trials are available from the Mallee Sustainable Farming Project web site: www.msfp.org.au

The seeding systems research is supported by graingrowers and the Federal Government through the GRDC.

Program 3.4.2 Contact: Ms Marion Murphy 03 5021 9413, Dr Jack Desbiolles 08 8302 3946

Long term seeding trials - 1999 results at two sites for a range of soil disturbance levels AND seed-placement configurations. The 'control' represents a district benchmark in technology, fertiliser input and cropping regime.
Long term seeding trials - 1999 results at two sites for a range of soil disturbance levels AND seed-placement configurations. The 'control' represents a district benchmark in technology, fertiliser input and cropping regime.

Seed/fertiliser placement configurations investigated in long-term trials
Seed/fertiliser placement configurations investigated in long-term trials

Range of soil disrutbance levels investigated in the long-term seeding systems trials. The tillage depths are 90-95mm (all shallow treatments) and 120-125mm (deep treatments)
Range of soil disrutbance levels investigated in the long-term seeding systems trials. The tillage depths are 90-95mm (all shallow treatments) and 120-125mm (deep treatments)

Region North, South, West