Fertiliser makes up a significant part of production costs. Typically it accounts for 30% of oilseed rape and sugar beet variables and 40% in cereals andpotatoes.

“Growers must ask themselves are they buying the right products in terms of grade, quantity and quality,” says Masstock’s David Langton. “Don’t just buy what you bought last year.

“World supply and demand for nutrients means fertiliser prices are relatively high. We’ve seen big rises – over 60% in the cost of phosphate since last year.”

But it could be false economy to over-react, he warns. “All farmers should get serious about managing crop nutrition – it makes good economic and environmental sense.

“Beware of taking unjustified phosphate and potash holidays. Grain prices are much higher than they have been recently and prospects look good. So there is more to lose by getting it wrong. Don’t jeopardise yield and quality through poor nutrientavailability.”

The most important purchasing drivers are soil analysis and cropping choice. “Consider precision farming options to assess nutrients on a sub-field level to fine-tune even further. With nutrient costs and output prices at current levels it is worth looking into.

Fertiliser buying

“It enables nutrients to be targeted where required and savings to be made where indices are high,” he explains. “Having a clear understanding of the nutrient status across the farm is essential.

“Be sure to use all available resources such as FYM, sludge and compost, particularly where indices need building. Consider broad-spectrum analysis to get valuable information on so-called minor elements to help target other nutrient applications.

“Micro-nutrients, as well as macro-nutrients, can limit crop performance and don’t forget pH has a key role in nutrient availability.”

Mr Langton stresses the importance of using good quality products. “If the plant requires a nutrient, you must supply it so as not to limit yield. Complex compounds are best, as each granule contains every nutrient.

“If you plan on using a blend, make sure it’s of good quality and that all its components spread to the required distance. Be sure to tray-test the spreader and don’t try to spread it too far.

“Ask yourself whether you are buying the right grades, particularly of nitrogen/sulphur products.”

Sulphur from the atmosphere continues to decline and, for optimum output, oilseed rape needs 100kg/ha of SO3, he notes.

“However, better establishment systems and warmer, wetter winters mean we’re getting bigger rape crops going into the spring, which don’t need lots of early nitrogen.

“If you’ve always applied your sulphur with the nitrogen you may be forced into applying too much N to get the required amount of S made available as the crop goes into stem extension.

“A high S:N ratio fertiliser, like Kemira GrowHow’s DoubleTop (27N:30SO3), provides more flexibility to deliver the sulphur when required – and it’s a compound.”

Given rising world demand, it is worth considering locking into current prices for NPKS products rather than risk waiting, because the price of P and K could rise, he believes.

Recently reported independent trials by Rothamsted, ADAS, IGER and SAC over two years and 15 sites show that urea is not as reliable as ammonium nitrate as anitrogen source for crops, he adds.

“Urea is subject to very significant N loss through ammonia volatilisation, particularly in dry conditions like those we experienced during April in 2002, 2003 and 2007.

“The variability in the trials was huge with urea – the N-loss range was 10-43%, with surprisingly high levels early in the season. This gave an average yield loss of 0.3-0.4 t/ha in cereals and 0.3% lower grain protein.”

On average, about 20% higher N rates were needed with urea than ammonium nitrate to achieve the same yield and grain N/protein concentration.

Whether those dry spells were all down to climate change is debatable. “We seem to be experiencing unusual weather more often, and this research shows that using urea is a risk that’s not worth taking.

“On top of the technical reasons, the urea price looks similar to that of UK-produced AN, so why take the risk?”

World demand is limiting the availability of imports of both urea and AN, which will put pressure on prices. “So plan your fertiliser requirements as soon as you can,” says Mr Langton.

andrew.blake@rbi.co.uk

Be prepared to rethink your fertiliser buying policy for next season’s crops, urges Masstock.