Inconsistent results from seeding oilseed rape using a subsoiler have led many growers to revert to cultivator-based sowing for reduced-cost establishment. Peter Hill describes a farmer-contractor’s evolving system
Providing loosened soil below rapeseed to encourage good drainage in a wet season and to give roots somewhere to go in a dry one is well proven as an essential component of establishment systems that do not involve ploughing.
But while the “extreme” technique of seeding from a subsoiler and relying on natural weathering to provide a surface tilth has met with inconsistent results on many farms, soil loosening is no less important when using a cultivator-based sowing technique.
Lincolnshire contract farming manager Mickey Daly has tried both approaches on the blocks of land he manages around Spalding and agrees that both have their merits – but also their limitations.
“With subsoiler broadcasting, you really need a well-weathered surface and even then getting adequate soil-to-seed contact for even germination is not very likely,” he says. “Broadcasting from a cultivator overcomes that by creating a nice tilth. But then you don’t get the benefits of deeper soil loosening to take out wheelings and ensure the plants’ long roots can grow to full potential.”
Mr Daly grows plenty of oilseed rape as managing director of Agriserve, which was set up to spin off the machinery and labour inputs of JL Farms and spread machinery investments through contracting and contract farming operations. This year, that all adds up to a workload equivalent to about 2000ha (5000 acres).
The crop features in his heavy-land rotation along with beans and winter wheat, but is absent from the light fenland mix of potatoes, sugar beet, peas, wheat and 122ha (300 acres) of pumpkins farmed by a specialist grower.
“Oilseed rape is still a useful break crop, as well as one with good profit potential,” says Mr Daly. “Our objective in developing a broadcast sowing system is to cover the ground quickly to get our own and customers’ crops established while grain harvesting continues and get even germination for ease of management.”
When deciding to move away from the traditional establishment approach of ploughing, pressing and drilling, or using a power harrow-seed drill combination after ploughing, the objective of cutting costs brought with it a reluctance to buy new machinery for the job.
“Our first approach was to sow using a Techneat Terracast system mounted on a Knight TriplePress set to work no more than the top 50mm (2in) of soil,” says Mickey Daly. “That worked well in terms of providing fast work rates and a tilth for good seed/soil contact, but it didn’t take out the wheelings.”
Putting a second Terracast unit on to a seven-leg Simba Flatliner equipped with a DD press took care of the wheelings and also provided the benefits of deeper soil loosening.
But although seed/soil contact was often good, that was not always the case where a lot of chopped straw was present.
“In some instances, we ended up with parts of the field establishing up to a month behind the rest, and that makes life difficult,” says Mr Daly.
Using the two implements in the same field brought home their relative advantages and especially the benefits of loosening soil beyond seed depth.
“You could see to the line where the Flatliner had been, especially on headland areas, and it was noticeable that we no longer saw the purpling leaves of plants stressed by poor drainage conditions,” he says.
The obvious answer was to combine the two elements and, as a matter of urgency, this was achieved in the first instance by running the TriplePress and Flatliner in tandem, each applying half seed rate.
In terms of crop establishment and early crop development that was a winner, even if it was not economically sustainable, says Mickey Daly.
“It produced a much better plant going into the spring and now we’re looking at some of our best ever oilseed rape crops, with fewer, stronger and healthier plants and a branching structure that interlocks nicely; hopefully, making them easier to harvest.”
Moreover, the questionable economics of running two implements on the job will be resolved this year when the two Terracast units are transferred to a Gregoire-Besson Discordon cultivator acquired last autumn.
This 6.7m (22ft) implement uses a leading row of discs to bust stubbles, then 13 low-draft rigid tines to break through any pans or compaction across the full working width.
Another row of discs follows to break up and level any clods thrown up by the preceding elements, with press rings bringing up the rear to consolidate the resulting tilth.
“We tried it to sow some oilseed rape last year, using the Flatliner for broadcasting and rolling after the Discordon, just to see what we could expect and the results were excellent,” says Mr Daly.
Installing both Terracast units will allow half-width sowing on short-work in addition to easy adjustment of seed rate if required using the electronic control system.
The Discordon will also get a clevis coupling on the back so that it can tow a roller press.
“If it’s too wet, we’ll take it off and use a Cousins Contour Cambridge roll or Väderstad Carrier with the discs raised out of work to finish the job,” says Mr Daly. “But at least we’ll be able to do the complete job in one pass if the weather’s kind.”
Another objective – of covering the ground quickly – will also be achieved by operating the outfit behind a four-year old 550hp Case IH STX500 Quadtrac that recently joined the fleet.