Oilseed rape growing certainly isn’t getting any easier at Folkingham Farms near Sleaford in Lincolnshire. Despite increasing pressures from verticillium wilt and flea beetle, the crop remains a key part of the partnership’s 1500 ha rotation. Margins are securely up there alongside 10.5t/ha first wheats. And the crop is particularly valued for its contribution to the black-grass control that is the driver behind all the family’s agronomic decisions.
“We’re very flexible rotationally these days to deal with black-grass” George Atkinson explains. “As well as wheat and OSR, we grow winter and spring barley, winter beans, peas and sugar beet on our mainly heavy clay loam ground. We typically grow rape every four or five years after either winter barley or wheat.”
At 4.2 t/ha last season, the dry summer knocked back five year average yields to 4.6t/ha. However, oils into the 47%s from their 530 ha of mainly DK Expansion and DK Expedient certainly helped make up for this.
“The crops were really nice and even with an excellent pod set,” notes George. “They would have at least matched the 4.8t/ha we achieved three years in a row with our long-time favourite, DK Extrovert if it hadn’t been for the drought.
“Interestingly, our best OSR yield – at over 5t/ha – came from 40ha grown after peas as a double break on a bad black-grass field. We grew the Clearfield variety, DK Imperial CL because we were nervous of SU residues from spring imazamox. It showed unbelievable vigour, suffered the least verticillium and delivered the best margin of all. It certainly seems to have something extra in the establishment department, especially after peas.
“The bulk of our current crop is DK Expansion and DK Expedient again and I’m not sure how we got most of it through the nightmare of establishment. Our soils came out of the summer dry and we had virtually no rain from the time we drilled in mid-August to the beginning of October. So the flea beetles, which we saw more of than ever, had a field day. We were lucky to lose only 25% of our plantings. Many round here had to write-off far more. In fact, we were very close to doing so too. But we held on to them and they’ve come through the winter surprisingly well.”
Much of the reason for getting most of this season’s OSR through has to be the ‘mild obsession’ George and Oliver have with sowing behind ultra-low disturbance legs which they have built locally. Using a Sumo Trio with the discs out, they put 50-55 seeds/m2 into 50 cm bands, working to only 9” at 7 km/hour to leave a virtually undisturbed stubble surface.
This creates a good tilth around the seed while waking-up the least amount of black-grass and preserving all-important soil moisture. A double press on the Sumo and a heavy set of Heva rolls working at a similarly steady speed close behind adds to moisture conservation and ensures the best possible seed-to-soil contact.
“We used to sow across the full width of the Sumo with the discs in,” recalls Ollie. “Apart from encouraging too much black-grass growth in the seedbed, we found the plants growing behind the legs had twice the length of root. So we now only put them there in the first place.
“Winter barley may give us more time for a stale seedbed, but we actually find our OSR does better after wheat. Barley really saps the nutrients and moisture; volunteers can be a real pain; and we bale the straw. Rape following wheat, on the other hand, seems to find more early nitrogen, phosphate and water. What’s more, the chopped wheat straw is a very valuable mulch, preventing our ground baking as hard as it can so easily do. Not having any bare ground seems to help with the flea beetle too.
“We spray off a decent flush of weed growth ahead of rape drilling whenever we can. “Centurion Max gives us a good early kill of any early emerging black-grass and allows us to hold off on our propyzamide until the second half of November for the best activity against the second flush. Combined with our establishment regime, this allows us to keep firmly on top of the weed.”