Winter has taken its toll on Britain’s soils, with heavy rain not only giving soils a battering through waterlogging and compaction, but also exacerbating existing nutrient deficiencies, with boron likely to be one of the worst affected.
Leaching of key nutrients such as boron and calcium, and lower pH levels, are likely to be the most common symptoms facing growers this spring. “Growers need to keep an even closer eye on their crops,” says independent agronomist Peter Parr. “It’s not uncommon for pH levels to fall following a wet season, but this also has negative effects on the availability of nutrients such as boron.
“OSR and other brassicas are particularly at risk,” he says. “Boron locks onto organic matter so light land in particular suffers from deficiencies. What was there will have been readily leached. Continued growth caused by the above average winter temperatures will have only compounded the issue.”
OSR is the most boron-dependent of all crops, requiring at least 320g/ha. But growers often fail to realise that each harvest removes about 80g/ha. “If no boron has been applied yet this spring, some urgency is required,” says Mr Parr.
“The key to maintaining boron levels this season will be in the timing. OSR crops are very thick and there is potential for some high yields, yet this speed of growth means they will need boron fast and soon.
“Not only does it help with growing points but it also plays a vital role in the production of pollen; consequently it affects seed formation. A boron deficiency has a direct and negative impact on yields,” he warns.
David Peach of Barclay Crop Protection agrees, adding that boron can also have a deleterious effect on root growth, thereby reducing the efficacy of nutrient take-up in general. “Ideally boron is applied prior to flowering and early stem extension. That’s now underway in most crops, so timing is going to be critical.
”Growers need a fast-acting, foliar application, such as Solubor at a rate of 1-1.5kg/ha, in order to help preserve yield potential.” It’s not just oilseed rape that’s at risk this year, points out Mr Parr. “Other brassicas will also benefit, as the warm atmospheric and soil temperatures will make transplanted brassicas grow rapidly,” he says. He recommends an application of boron straight after planting, and another application three to four weeks later at early head formation.