December 4, 2014
Shropshire field study highlights OSR establishment differences
Clear differences in the speed and evenness of initial oilseed rape growth as well as early slug and weed pressures have been recorded between the seven modern establishment systems employed in the innovative Agrii field study being undertaken this season at Chillington Estate, Codsall near Wolverhampton in the West Midlands.
Each of seven systems from six manufacturers drilled DK ExPower at 50 seeds/m2 into around four acres of freshly-harvested wheat stubble with plenty of surface trash in front of visitors at a mid-August demonstration day. Since then, agronomist Peter Jones and farm manager, Simon Collins have been monitoring the strips in the 30 acre field regularly, photographing them each week as a record of progress.
From simple subsoiler seeding to power harrow and direct drilling, the wide variety of discs, tines, coulters and packers involved dealt with the favourable sandy loam ground conditions at sowing well, the key contrast being major differences in the degree of surface soil disturbance produced and visible trash left behind.
On the one hand, the Opico HeVa subsoiler left the stubble surface virtually intact, with Claydon Hybrid and SUMO DTS also giving less in the way of surface effect. On the other, the Lemken Solitair power harrow drill produced a not far short of traditional seedbed surface with the Vaderstad Top Down and Spirit, Lemken Karat and Simba DTX systems also leaving significantly more disturbed stubble finishes.
“Interestingly, it’s this surface cultivation contrast that seems to have been behind most of the differences we’ve seen between the systems over the first 10 weeks of our study,” reported Peter Jones.
“The rape was definitely slower to emerge from the ground receiving the most surface cultivation. “This was almost certainly because more incorporated trash interfered with germination and early nutrition; especially as we deliberately didn’t include any seedbed nitrogen to give each system the same establishment challenge.
“Noticeably quicker to emerge the drillings from the least disturbed ground may have been, but they encountered serious slug problems at cotyledon stage. So much so that they needed three doses of pellets in three weeks compared to a single pelleting everywhere else.
“While it didn’t interfere with things below the ground, leaving the trash on the surface clearly meant much more protection for slugs under the September sun,” he reasoned. “In contrast, the more cultivated surfaces were far less slug-friendly, although they still maintained sufficient moisture down below not to interfere with the crop.”
Interestingly, however, more surface cultivation also appears to have been more conducive to the early germination and establishment of the large amount of charlock and runch the Chillington study field is known to carry. As a result, the early weed population in these strips presented a far more visible challenge for the autumn herbicide programme.
Although, generally favourable early growing conditions meant few discernible differences across the field by mid-October when viewed from a distance, closer inspection showed more even establishment overall from the regimes involving the greatest surface cultivation.
However, there were obvious differences between the individual systems, with one in particular standing out noticeably for its evenness.
“Were the drilling conditions and establishment season to have been less favourable, I’m sure the differences we’re seeing would be even more apparent at this stage,” observed Simon Collins. “It will be interesting to see how the strips develop relative to each other over the rest of the season, what inputs they require and how well they perform.
“Compared to our sub-soiling followed by ploughing and power harrow drilling, the work-rates from all the systems were very impressive. But there are a lot of questions that remain to be answered before we consider making a change. Faster establishment is a priority for us, but we also need a regime which will give us the quality of seed-to-soil contact we get from our current system.
“At the same time we have to consider any changes we may need to make to other aspects of our agronomy to make the most of any alternative. Like cutting and carting the straw to reduce the slug challenge, for instance. Or a straw rake ahead of drilling to improve the consistency of sowing.
“That’s why it’s so valuable to have this sort of field-scale study under our own conditions rather than having to rely on observations from demonstrations in the wide open spaces of the east where the OSR challenges are very different from our own.”