Southern Farming Systems (SFS) are running a disc versus tyne seeder trial this season.
The trial is part of a Grains Research and Development Corporation (GRDC) research project, focusing on maintaining profitable farming systems with retained stubble in Victoria and Tasmania.
This replicated trial was sown on April 12, into dry conditions, at Streatham in south-west Victoria.
The disc seeder sowed canola into 30cm high stubble from a 2015 wheat crop. This year a machine with 25cm row spaces was used, which created some challenges, as the 2015 crop was sown on 30cm row spacings.
The tyne seeder was used to inter-row sow canola into 15cm high stubble. Sowing was on 30cm row spaces in both 2015 and 2016.
Initial germination counts have highlighted potential dangers of dry sowing with disc seeders. There were far less plants on average in the disc sown plots compared with the tyne sown plots.
Germination and establishment was also higher in the burnt areas than where stubble had been retained. There may be more viable seeds in the soil that will germinate once it rains, but establishment in the tyne sown plots has been reasonable in the dry sowing conditions.
Canola seeding rates were set to target 35 plants per square metre and sowing occurred with 80kg/ha MAP fertiliser.
Data collected so far shows the seed sown with the disc has not established because of fertiliser toxicity or lower soil to seed contact than that achieved with the tyne.
Urea was also applied at sowing at a rate of 60kg/ha in half of the plots for each seeder. This has had a detrimental impact on emergence, as evidenced by the differences in treated and untreated plots where stubble was burnt.
Although the Equalizer disc seeder that was used for this experiment uses a twin tube set-up, which separates seed and fertiliser, seed damage still occurred.
Strangely, where stubble was retained, there was no difference in the plus or minus urea at sowing treatments.
The emegence data from this trial has not yet been analysed but the average plants per square metre indicate that there will be a statistically significant difference between some treatments.
SFS projects coordinator Paul Breust said they will monitor the emergence after decent rain to see if any more seeds germinate.
“Past experience has led to the belief that the disc is more reliable at establishing crops in low moisture seed beds but the data from this trial shows otherwise,” he said.
“It is commonly known that fertiliser toxicity can be a problem in dry seed beds with disc seeders, especially with canola. The data certainly supports this and the current very low plant numbers in both burnt and stubble retained treatments for the disc may require re-sowing.”
Soil moisture was also measured in the seed furrow for all treatments in this field trial.
According to Mr Breust, a common perception is that tyne seeders dry out the furrow more than the disc.
“This is supported by the data but there was no subsequent increase in germination, thought to be due to increased fertiliser toxicity in the disc furrow,” he said.
SFS will report on the progress of this trial throughout the season. Look for updates at: https://thestubbleproject.wordpress.com/
Published by Fairfax in the Stock and Land, May 12, 2016, 10:05 a.m.