Article taken from Arable Farming Magazine
By Abby Kellett
Steven Tuer's top-performing oilseed rape crop yielded an impressive 7.2 tonnes per hectare with hybrid variety Incentive. But perhaps more notably, his oilseed rape crops averaged nearly 6t/ha overall last harvest. In 2010, Mr Tuer took steps to change the way he grew oilseed rape at Hutton Grange Farm, having been dissatisfied with previous crop yields. Since then, with help from his agronomist, Chris Martin of Agrovista, he has reduced seed rates, delayed sowing, improved establishment rates and applied a more crop-specific approach to canopy management and is now reaping the rewards. One of Mr Tuer's biggest challenges is his soil. With 80% of his farm comprising heavy clay, he is limited to winter cropping and has to work continuously to improve soil structure to aid drainage. He says: ""On a dry year oilseed rape can do very well, but on a wet year it can really struggle. We are very reliant on soil structure to help us on a wet year."" To improve soil structure, he keeps his cultivations to a mini-mum and only ploughs before barley to reduce weed carry-over. ""We have a three-metre mounted cultivator, which is based on subsoiler legs followed by shallow discs, followed by a packer. The cultivation is based around a one-pass system. ""By minimising the amount of cultivations we are doing, we are minimising the amount of organic matter loss and that makes a big difference," he says. Alongside preserving soil organic matter, he is constantly trying to add it where possible. ""We apply lots of pig manures back on the ground, pig slurry is applied in spring, farmyard manure in autumn and we incorporate a lot of straw.""
Optimising canopy size
Among the major changes Mr Tuer has made to his approach to growing oilseed rape are reducing seed rates and delaying drilling, with the aim of reducing canopy size ahead of spring. By limiting plant numbers and plant size, Mr Tuer and Mr Martin believe they can achieve an optimum canopy size. Mr Martin says: ""Essentially, we are trying to create a canopy which is going to maximise seed number and seed size. A lot of work has been done which shows we need a much smaller canopy at flowering than we have all targeted. ""We are trying to get as much leaf as possible. If the canopy is too thick we get lots of flower, lots of stems and pods, but not enough leaf. ""It is like trying to grow solar panels and the best solar panel for photosynthesis is your leaf. If you have too many flowers, light just gets reflected."" Mr Tuer delays drilling until early September, while most farmers in the North tradition-ally drill between mid- and late-August and so good seed vigour is crucial, he says. This is a characteristic which can be found in Incentive and also Anastasia, which achieved similar yields on the farm, he adds. When drilling, he aims simply for soil coverage as opposed to drilling at depth, which also aids establishment, he maintains ""We don't do much pre-em [herbicide] application and so we do not need depth. ""Because we generally follow rape after barley, we can go in with a stale seedbed technique, so when it comes to drilling, we have no cultivations to do prior to getting seeds in the ground."" So although drilling is delayed, this approach to seedbed preparation means all oilseed rape crops can be drilled within a two-day window. But it also means Mr Tuer has to be extra-vigilant with regards to pest attack during the early stages of crop development. However, because the seed rate is reduced each individual plant is bigger and so is more able to recover from pest damage, he says. Seed rate for the farm's oilseed rape crops is 25 seeds/ sq.m, which is roughly half the industry standard rate, accord-ing to Mr Martin. ""We sow at 25, with the aim of achieving 20 plants/sq.m in spring. ""We expect to lose between 20-30% in a good year and up to 40% in a bad year. Generally by going in at a lower seed rate we get better establishment," says Mr Martin.
Mr Tuer manually varies his seed rate during drilling and is prepared to increase seed rate on headlands and other areas where he expects to have lower establishment. He says: ""I vary seed rates across all crops and I do it manually in the cab as opposed to using a GPS system. No GPS system can replicate what a clued-up operator can achieve. ""It's about knowing your soils, knowing where we have had compaction in previous years and where we might have a slug or drainage problem and adjusting the seed rate accordingly."" Despite the fact the 2015/16 season saw low disease pres-sure, Mr Tuer and Mr Martin still opted for a robust fungicide programme in order to ensure the crop was capable of achieving its yield potential. Mr Martin says: ""This fungicide programme did a good job at keeping the crop clean, although it was quite a low disease risk season and the fungicide programme was very robust anyway. ""It is considered the 'Rolls Royce' programme but we knew the crop had potential and we wanted to maximise that."" Cabbage stem flea beetle, although providing serious problems for some growers, was a 'no bigger problem than usual' on-farm. One application of cypermethrin was enough to protect the crop from potential damage, says Mr Martin. However, black-grass is an increasing problem at Hutton Grange, although the two men believe late drilling and a stale seedbed go some way towards controlling the weed. As well as applying Kerb (propyzamide) at post-emergence, this year they have planted a black oat and vetch cover crop mix, in an attempt to reduce the black-grass burden on some of the farm's heaviest soils. ""We have some very wet heavy soils which traditionally flood on a wet winter and which is horrendous for black-grass, so we have put a black-oat and vetch cover crop in. ""They both grow slowly in autumn which encourages black-grass to grow alongside them so we can spray it all off with glyphosate," says Mr Tuer.
Crop nutrition
A lot of pig slurry is spread on barley stubble before cultivation, so the soil gets an early dose of nutrients and of nitrogen in particular. While Mr Tuer would like to apply an additional dressing of pig slurry in spring, often the weather does not allow for this. He says: ""Once stem extension begins, there is no way we could pull an umbilical system through the field, so it just depends on whether it is dry enough to apply slurry earlier."" Additionally, he applies two to three split applications of bagged N fertiliser to meet crop demand. The timing of these applications depends on the size of the crop and the crop's potential. Mr Martin says: ""For maximising seed number, the key is having the perfect canopy at flowering and that means having a green area index of about 3.5 which generally means it contains 175kg of nitrogen at that stage. ""We then try to build enough nitrogen to match how much it needs in that period so it has enough nitrogen to keep the crop greener for longer. ""Steve uses a late foliar nitrogen spray as well to help with this.""
Mr Tuer adds: ""We are always looking forward and making sure we are not pushing the crop too soon by applying early nitrogen, but where the crop is thinner we will go in with a more traditional early application. ""Where we have a thick crop we hold off as long as possible."" Mr Tuer estimates an overall agchem input cost of about £200/ha and a £175/ha spend on fertiliser. While costly, he and Mr Martin believe their spend on inputs can be justified. ""In the spring time we are always thinking, are we are on target for a big yield? If so, do we go for the slightly better chemical combination or do we go for a cheaper option? Do we give it an extra few kilograms of nitrogen now or do we save it for later? ""If the crop's potential is 6t/ha, then it is worth the extra chemistry," he says. All the strategic changes which have been made to oilseed rape management at Hutton Grange have resulted in a shift in expectations. While 6t/ha was previously considered unachievable, it is now the annual yield target, says Mr Tuer.