Applying liquid nitrogen at the same time as till-seeding oilseed rape can result in significant establishment improvements, especially in challenging conditions like last autumn, according to recent trials carried out in Denmark and the UK. But using the appropriate establishment method remains vital.
Speaking at the launch of Lincolnshire company Opico's Nitro-Jet system last week, Masstock's northern technical development manager Philip Marr (right) explained that, although there's no right answer for rape establishment as every season is different, there are two criteria that must be remembered: Good seed-to-soil contact and good, free-draining soil structure.
"Growers have lost sight of the importance of root structure in the establishment of oilseed rape," he saidd. "As rape is a vegetable seed, it needs an open soil structure to establish a good tap root and overall root mass early on."
Seed beds should be fine, firm and moist, he said. "By till-seeding (ie using a subsoiler) rather than broadcasting, you're allowing more moisture to come up where the tine passes through soil and a looser structure for the root to establish."
The nutrient content of oilseed rape was also very different from that of wheat and barley, Mr Marr explained. "Crops have a high demand for nitrogen in August and September and then again from late February into March and April. And, because the primary roots can't handle P and K early on, by applying nitrogen directly where the seed is being drilled, which they can access, you're creating a growbag situation for young plants."
"By giving plants a boost pre-winter, better overall establishment can be achieved, and it could mean that less nitrogen is needed come spring, as well as one less pass post-drilling," added Mr Marr. Green Area Index results have also shown that the nitrogen applied at drilling time is present in plant in the spring, which could result in a reduced requirement come spring fertilising.
Band application of nitrogen could also help growers meet ever-increasing NVZ legislation, he said. "Although you're only allowed to apply 30kg/ha nitrogen in the autumn, by applying directly onto the band, it results in 45kg/ha being applied to the crop, but only 15kg over the whole field."
All kit could achieve the final target of good establishment, but equally all could fail. It was like a jigsaw puzzle; every piece was important, concluded Mr Marr. "The most important piece of kit is the spade, or a penetrometer to assess pre-cultivation requirements. Ultimately, yield is very important in relation to the cost of establishment; particularly as we could see prices rise to as high as £300/tonne."