Start it off strongly, keep it going steadily without unnecessary stress, structure it for the best light interception and keep it green from top to bottom as long as possible.
This is the OSR recipe that earned Scottish grower, David Fuller-Shapcott sixth place in the first-ever national oilseed rape YEN crop competition with a yield of 5.6 t/ha despite the challenges of heavy clay loam soils recognised for their ‘impeded natural drainage’; soils that are unforgiving if anything goes wrong, not to mention a paradise for slugs.
The 50ha or so of winter rape his family-run company grows each year at Sweethope Farm in the Borders near Kelso in a six year rotation with winter and spring cereals is currently delivering a rolling average 4.25t/ha for a gross margin of just under £1000/ha and net margin of over £450/ha.
That the rape does so well despite the challenges of the conditions is a testament to the continual cropping improvement approach of David supported by his Wallace of Kelso agronomist, Catriona Bancroft; an approach which has paid dividends in pushing average biscuit wheat yields to a current 11-12t/ha and through which they’re targeting a consistent 4.5-5t/ha from their OSR.
“You can’t expect things to get better if you don’t make changes,” he insisted. “We’ve made great progress with our cereals by dropping second wheats entirely and extending our rotation to include two spring and two break crops. This allows us to grow two first wheats – after OSR then again after spring oats – followed by spring and winter barley before going back into rape. It’s had the added benefit of moving rape out from what was one year in every five.
“We need the winter barley as an entry for our rape as we generally can’t harvest spring cereals until well into September, if not October. Even so, we have to be pretty quick off the mark getting our rape in as the barley isn’t fit to combine until the first week of August at the earliest. Although we’re trying to push our sowing forward, we often struggle to get it done by the end of August.
“This and our very limited staffing means our establishment regime has to be quick as well as reliable. All the more so as we get the barley straw baled and removed to minimise slug cover and only have a very short window in which to get the OSR away on ground that cools down so rapidly as it wets in the autumn.”
Success with OSR at Sweethope Farm is firmly based on sowing aggressively establishing varieties with a specialist seed treatment and starter fertiliser from a heavily-adapted Weaving Subdisc in an interesting blend of sub-casting and drilling.
David has fitted a tool bar with seven sets of heavy-duty Weaving double disc coulters and press wheels to the back of the 3m cultivator – behind its Güttler rollers and in line with each leg. With a seeder unit on the Subdisc and a front-mounted fertiliser hopper on the tractor, this allows both seed and fertiliser to be dropped into 43 cm rows into well-loosened, reasonably cultivated ground.
Clever engineering automatically links the fertiliser and seeding systems for the most precise control, and allows the depth of sowing to be adjusted independently of cultivation depth.
“We’ve played around with all sorts of variations on sub-casting over the years,” recalled David Fuller-Shapcott. “The system we have now gives us good soil disturbance at depth, reasonable seedbed quality and good control over of sowing depth in a single pass. Importantly too, it’s light enough for us to operate with our 145hp tractor and flexible enough for us to cope with the fact that August has become our wettest month of the year.
“For the easiest storage and most cost-effective purchasing, we use our standard 10:15:21:20 winter cereal top dressing compound fertiliser at drilling, applying it at 20kgN/ha – or the equivalent of 60kgN/ha in the row. This works well, though we might be able to improve things further by using a liquid fertiliser.”
Drilling is at 30o to the tramlines (which remain in exactly the same place throughout the rotation courtesy of RTK) followed by rapid double rolling in parallel to the tramlines. Because the cultivated ground can bake over hard in the blink of an eye, the heavy Opico rolls equipped with shatter boards are often run right behind the seeder. Dual wheels on the rolling tractor and a strict 4mph limited give the billiard flat job David wants for the best seed-to-soil contact and the least slug-friendly environment.
A sowing rate of 12-15 seeds/linear metre – the equivalent of 24-30 seeds/m2 – may seem on the low side given the level of slug threat at Sweethope. But post-harvest counts show the combination of hybrid varieties like DK Expansion which establish aggressively, a phosphite-based seed dressing, well-placed fertiliser and good, moist-preserving seedbeds are resulting in the 10-15 plants/m2 spring populations he targets.
“Hybrid rape always does best at low seed rates,” David Fuller-Shapcott pointed out. “The plants get a chance to fill out rather than being forced up. The last thing we want is stands that are too thick if the winter proves more favourable than usual. That way we avoid any growth check from early PGR use for height control. We also minimise the amount of slug fodder we provide.”
Where they can be achieved, well-rolled seedbeds are also valuable for the edge they give to residual herbicide activity in dealing with broad-leaved weeds and the annual meadow grass that can cause horrendous problems locally.
No opportunity for stale seedbed control ahead of their OSR means David and Catriona make the most of pre-harvest glyphosate in the preceding winter barley to stay ahead of AMG, in particular.
They will use a pre-em in the rape if conditions are right. However, with slugs posing such a threat they tend to wait until they know they have a crop before spending on herbicides.
“Going in with Banastar at early post-em rather than pre-em also means we can save on a sprayer pass by combining it with the crop’s graminicide and the early trace element boost that’s also an important element in our efforts to optimise crop establishment,” pointed out Catriona Bancroft. “It’s valuable too with David’s very tight staffing.”
“We routinely use propyzamide as a rotational tool to nail AMG and grassweeds like brome that might otherwise be encouraged by the farm’s progressive rotation-wide move into minimum tillage. We don’t apply this until December as a rule, though, along with our first light leaf spot spray and extra trace elements. So it’s useful to get the greatest length of residual activity from our early herbicide programme.
“Supported by the best light leaf spot resistance we can get in our varieties, a relatively late start to spraying, in turn, gives us the flexibility to keep on top of the disease in a wet spring like this season when our stem extension spray can’t go on until green bud.
“Here again we include trace elements based on the broad spectrum soil analysis and regular tissue testing we depend upon to get our nutrition as spot on as it can be. Although light leaf spot is a serious challenge in our area, we put effective foliar nutrition on a par with well-targeted fungicides in our agronomy; not least because healthier plants are essential in dealing with an increasingly difficult chemical battle with light leaf spot.
“Where necessary, we use foliar P in the spring too because our heavy clays are very good at locking-up phosphate. We invariably find our crops need extra boron and molybdenum. And we’ve seen big responses to foliar K and S with our mid-flowering sclerotinia spray.”
Having established it robustly, the whole focus of rape agronomy at Sweethope Farm is on keeping crops growing as steadily as possible without unnecessary stress. On his cold soils David prefers varieties that don’t rush into stem extension too rapidly so they only get going when they can access the nutrients they need.
An average of 180kg/ha or so of spring N – as inhibited urea for its slow release value – is applied in two splits, complemented with polysulphate to give a good balance of available sulphur and potash on the farm’s magnesium-rich clays. This ensures the crops get the little and often supply of nutrients they need without straining already stretched spring workloads.
“Along with even establishment at low seed rates and stem extension Caryx, our aim is to develop * bushes rather than Christmas trees for the best light interception,” David stressed. “Then, just like solar panels, it’s a matter of making sure they work as efficiently as possible for as long as possible by keeping them green from top to bottom and desiccating as late as we dare.
“Recital as our mid-flowering spray helps green leaf preservation as well as disease control and going back in with Amistar at late flowering enhances this while combatting the alternaria that Catriona finds is becoming much more problematic up here in recent years.
“We tend to leave desiccation until the upper pods are almost shattering as we go through the crop. So pod shatter resistance and the pod sealant we used for the first time last year are really useful. As is a strong canopy that stays upright throughout for nice, even combining without the reel having to work.”
In pushing for their target of consistent 4.5t/ha-plus winter rape, David and Catriona are looking at a whole range of improvements. They want to drill earlier where possible; fit their varieties’ development characteristics more closely to the drilling slot; and, further improve their establishment. They are also actively exploring further fine-tuning the crop’s nutrient balance throughout the season and ways of reducing sunlight reflection from old petals at the end of flowering.
“Being part of the YEN network is incredibly useful in identifying these and other possible opportunities for improvement,” concluded David Fuller-Shapcott. “At the same time, our local ADHB benchmarking group keeps us well-focused on the most important drivers of overall profitability as much as crop performance.”