I got dusted off on a beautiful day yesterday to help with seeding some canola trials near Beverley, about 1.5h drive SE of PER.
Common agricultural trials are for things like cultivar (aka variety) comparison and evaluation. Generally, plots are 1.2 m (6 rows) wide x 10 m long. They need to be sown accurately in a grid with a precision seeder. A typical trial might be 12 varieties x 4 replications , so 48 plots, in a RCB (randomised complete block) statistical design with an ANOVA (analysis of variance) conducted on yield, or other parameters, at the end to separate effects.
Working in an area 40 m wide x about 100 m long, we sowed about four trials, running back and forth across the width of the site (ie. 4 plots sown in each run). Prior to sowing, the area was sprayed with herbicide with the rig on the ute.
Needing cm precision, we set up a differential GPS station locked to about 19 satellites. That in turn controlled the location of the tractor, which has fully automatic steering capability. So, once I swung the machine around and generally lined it up for another 40 m run, all I had to do was hit the auto-steer icon on the screen, switch on the precision cone-seeder seed feeding mechanism and lower the hydraulically-controlled tynes and press-wheels prior to the edge, then not touch the steering wheel until the run was completed and it was time to turn off auto-steer and the seed feeder and raise the tynes before steering manually for the next run.
The other operator was on the seeder, feeding the envelopes of coded seeds into the canister above the inverted cone (designed to spread the seeds very evenly) successively one at a time, with the gate opening precisely under automatic GPS control.
This is the same minimum-tillage methodology almost universally used in broadacre cropping. The tynes cut a narrow furrow into which the measured seed and fertiliser drops, while the rubber-edged press wheels apply pressure to ensure good soil/seed contact.