Fine-tuning seed rates to soil types plus more precise fertilising seem to be reaping useful rewards on a Wiltshire farm.

Early results from the first season’s full-scale use of the Courtyard Partnership’s Intelligent Precision Farming approach based on field zones at Ramsbury Estates, Marlborough are much better than expected, says CP’s Vince Gillingham (right).

Overall savings, at current input prices, are an estimated £21/ha (£8.50/acre) with no apparent drop in crop yield. Indeed, this season’s wheat output is well up on that of 2006 before manager Duncan Lee (left) adopted the IPF approach (Arable 23 March & 21 September, 2007 and 21 March, 2008).

The figure could have been much higher. But, unfortunately, the farm’s pressure-based sprayer was unable to vary liquid nitrogen doses according to the zones.

So the potential extra savings – which Mr Gillingham estimates at £50/ha (£20/acre), based on the farm’s earlier variable rate trials with solid fertiliser – were, at least partially, forgone.

The farm’s new Househam sprayer with vari-target nozzles should permit zoned nitrogen adjustments for next season’s crops, notes Mr Lee.

Last season, the first that Ramsbury Estates has sown cereals according to field zones, produced encouraging results

Although clearly pleased with the results and fully intending to continue with the zoned approach, he cautions against reading too much into one year’s results.

“We’ve had some cracking yields, but it’s just one season and there are many things that interact to affect them.”

Only after several more years using IPF, perhaps comparing it in split fields with a more traditional approach, will its true value become apparent, he says.

“We can certainly see that it has been evening up the fields. The stubbles and straw swaths are much more even.

“We still get a lot of variation on headlands because of vermin, but our two Lexions with yield mapping have confirmed our gut feeling that the crops were more uniform.

“The important point is that we’re putting the products in the right places. For example, we reduced seed rates considerably in the valleys, maintained yields and haven’t had any flat crops in them, which is pleasing.”

Commenting on comparative wheat yields for 2005 (pre-IPF) and 2008, Mr Gillingham highlights the 13ha Top Hill field (see maps).

“The maps show the marked decrease in variability across the field through the use of IPF management zones. The patches of poor yield to the northern and southern ends have been evened out, with the worst patches eliminated.”

The 24ha of Parsons Attwood show a dramatic improvement on the left-hand side of the map between 2005 and 2008, so evening out the overall output. “This area is a thin chalky soil, which is naturally less fertile than the rest of the field.”

It was there that assistant manager Martyn Hall increased the Solstice seed rate significantly last autumn, says Mr Lee.

The initial IFP work at Ramsbury, aiming to raise the often low potash and phosphate indices of the estate’s diverse and hilly downland, clearly contributed to this year’s result, Mr Gillingham believes.

“We’ve increased phosphate levels on all the zones which had indices below the target index 2.

“There are now no zones on the farm below target for phosphate.”

Importantly none of those within the target range in 2006 have dropped below it, he points out.

Only one zone on the farm remains below target index of 2- for potash, all others below it in 2005 now achieving it.

“All zones previously within or above target for potash remain so.”

The saving from varying seed rates is not particularly significant, he admits. “The average was £3/ha. Variable seed rates have a bigger agronomic effect.”

But at current input prices there is a potential overall saving of £74/ha (£30/acre), once variable N rates are again applied, he calculates.

The annual cost of IPF, including soil sampling, fertiliser recommendations & GPS variable rate plans, is about £5/ha (£2/acre).

IPF Professional Scheme

With demand for IPF growing fast, a network of soil zoners has been set up across the UK, says Mr Gillingham.

“We’ve also begun building a community of IPF approved advisors. They will be given training and support to ensure they can help their customers make the most of the opportunities like those evident at Ramsbury.”

An IPF website will also soon be launched to enable farmers and advisers to adopt zoning across the country in their own offices.