GOOD START ESSENTIAL FOR OILSEEDS
Lee Bennett
Getting oilseed rape off to a good start is the key to making a profit from growing the crop, farmers attending a seminar hosted by Southern Harvesters near Petworth, Sussex heard.
But too many growers are still missing out on a huge amount of yield, Grainfarmers’ arable technical manager Lee Bennett told the audience, with the average yields of 3.2 tonnes/ha being well below the 5.7t/ha that can be achieved. With the average arable farmer growing 65 hectares of the crop, he says that is over £26,000 income being missed:
“The first step to addressing that loss is to get good soil structure before sowing, so the plant can establish a good root system – especially a strong tap root so it can access moisture from depth.
“Then you need to achieve accurate seed placement. The crop’s yield potential is set at establishment, and if any part of your establishment regime is wrong you have already limited its yield potential”.
Moisture loss during cultivations was a key problem, with a single pass machine like the Solo – “minimum passes but maximum tillage” - offering the best chance to retain it efficiently. By contrast multiple passes – whether non-inversion or ploughing and secondary cultivation – could be much more expensive and risk serious moisture loss.
“Shallow cultivations (scratch and sow) have a place on wolds and downland, but if you have not created the right conditions for the tap root the crop could be vulnerable to drought at the very time it is trying to form and fill pods.
“Seeding off the subsoiler is not suitable for all soil types and may not achieve the correct conditions for effective rooting in wet seasons.
“Ploughing is expensive and time consuming, and prone to moisture loss, as well as leaving the soil prone to erosion and also risks causing a pan in wet conditions. Its benefits are that it leaves a clean seed-bed and mineralises N which helps the crop get a start”.
GROWING OILSEEDS less frequently in the rotation could be the key to controlling disease costs and achieving best yield, says Richard Cartwright, from Chichester Crop Consultancy:
“Everybody remembers when the first grew oilseeds, the best yields were often gained in those first years. But with tighter rotations – some people have been growing it alternately with wheat – yields have suffered.
Extending the gaps between growing it would also help reduce the impact of diseases like clubroot and verticillium wilt. The latter was confirmed for the first time in 2007 and may be responsible for high levels of yield loss in tight rotations.
Good variety selection and autumn fungicide timing could help control diseases like phoma, but sclerotinia is a very difficult disease to predict, with the previous history of the farm being the key factor in determining likely infection levels. After last year, a greater number of crops could be at risk this year and in the future
“Oilseed rape is a hungry crop and needs a high level of nitrogen input, and it may be more sustainable in the present climate to use other break crops to extend the rotation such as peas and beans, which have the benefit of fixing nitrogen for you as well”.
Richard Chromie (left) and Richard Cartwright (right)
ESTABLISHING a good root system was essential to enabling the plant to access the fertiliser applied to it, Richard Cromie from Crop Management Partners said.
He highlighted the potential differences in the efficiency with which the crop can forage for both nutrients and moisture according to how well rooted it was, and the impact that had on production costs: “80% of root development is complete by the end of December, and if it is not done then it never will be.
“A really well rooted crop will be able to access both soil reserves and applied nitrogen more efficiently than a poorly rooted one, and so might need about 160kgs/N, whereas a poorly rooted one might need 210 kgs/N ha.
“When you follow the calculation through with the higher yields being achieved by the crop with better root structures and the current higher fertiliser pieces, the differences in cost of production per tonne of seed produced are huge”.
And he warned growers against relying on soil reserves or autumn-applied manures to supply sulphur, pointing out that it was a highly soluble element, so most of that applied might be lost during the winter. “Most crops now need 70 – 80 kgs/SO3”.
ROB IDDESON stressed the importance of achieving the right combination of a structured sub-soil for root development and a fine, even tilth for seed germination, and then swift, effective consolidation to achieve good seed-to-soil contact and minimise moisture loss:
“Our new SL cultivator is designed to offer this type of cultivation on all soil types. It offers consistent performance, the opportunity to achieve timely, effective cultivations and works across any soil type or in different styles of non-inversion tillage. It is a truly flexible machine for the future.
“The Aqueel 2 is proving adept at following up one pass sowing systems and achieving that consolidation. Because the roller itself flexes slightly, it does not block even though it is not scraped, and can run on far fresher, more recently cultivated soil. This helps give the crop its best possible start.
“This is a far more secure system than any of those which require multiple passes to establish the crop. The more time and more passes taken to do the work, the more chance there is of something going wrong”.
