A TRIAL being run by the Liebe Group in Latham is showing that seeding canola into deep ripped soil can severely reduce plant establishment.
The trial, which was on show at Liebe's Spring Field Day on September 10, is also showing that deep ripping canola post seeding pre-emergent (PSPE) can help but often requires extra labour and machinery during seeding, while deep ripping canola early post emergent (EPE) could be a solution if plant injury can be managed.
Liebe main trial site host Dylan Hirsch said the aim of the trial was to demonstrate and quantify the plant establishment penalty of seeding canola into deep ripped soil.
"It was also to show the loss of plants by deep ripping EPE - and to check if delaying deep ripping until EPE still produces a yield boost compared to ripping in typical summer conditions," Mr Hirsch said.
"We have always seen canola and deep ripping as a package, because of canola's ability to use subsoil moisture and produce a reliable yield response, and the tillage effect of stimulating weeds where they can be controlled with glyphosate or selective herbicides.
"However it has been risky with plant establishment sometimes compromised by poor depth control in softer sands - this plant establishment reduction can undo the yield response of canola in this system."
While some other farmers are deep ripping canola after seeding it to manage this issue, the Hirschs didn't want to purchase an extra tractor and labour to do this at a time when they were seeding other crops.
After seeing the effects of EPE deep ripping trial strips on previous canola crops on that property, Mr Hirsch decided to implement this trial to better assess the effects of EPE deep ripping.
The soil was previously deep ripped in 2017, and is a yellow sandy loam, which is considered easy to rip when there is moisture in the soil.
Mr Hirsch said the summer deep ripping happened in ideal conditions after about 100 millimetres of summer rainfall.
"550mm depth was achieved easily with the Nufab Tilco ripper and the site was seeded to 410XX canola at 1.6 kilograms per hectare on April 6 in dry conditions at a target depth of 15mm with a JD 1830 air hoe drill with split boots," he said.
"The area received 6 to 7mm of rain on May 6 which was enough to germinate some plants but was extremely patchy, while a subsequent wind and rain event on May 24 did not germinate the remaining plants, which were presumed to have shot from the previous rain event."
The establishment across unripped and EPE ripped trials averaged seven plants per square metre prior to EPE ripping on July 5, which is satisfactory for the Hirschs for 410XX canola.
However the summer ripped plots only averaged 1.8 plants/sqm, which may have been due to poor depth control when seeding into ripped soil, or other factors.
Mr Hirsch said the EPE plots were ripped 'interow' on July 5 with the only visual effects on plants being from tractor wheel traffic.
"Some plants were impacted by tynes and establishment counts on July 30 on EPE were down to 5.2 plants/sqm, a reduction of 26 per cent," he said.
"Surviving plants were visibly stunted and were shorter than the control strips, however as at September 1, it appeared that the EPE ripped plots had caught back up.
"Normalised difference vegetation index (NDVI) imagery from August 29 indicated the normal summer ripping plots had visibly lower NDVI scores, whilst you could not differentiate between unripped and EPE ripped plots from NDVI imagery."
Other EPE ripping strips on different areas of the farm showed different responses, from virtually zero plant count reduction to more than 70pc, which indicates that EPE ripping results may be strongly dependent on the season and soil type.
The trial at Latham was supported through the Liebe Group's current project 'The Gen Y Paddock Challenge', through funding from the Australian Government's National Landcare Program Smart Farms Small Grants Program.
