3 April 1998

Soil mapping with precision wins savings

Soil mapping with precision wins savings

By Jeremy Hunt

A TWENTY-TWO % saving on fertiliser costs worth £2000 has been achieved on a Scottish Borders arable farm after variable rate fertiliser application followed soil mapping on 243ha (600 acres).

Colin McGregor, who farms 341ha (843 acres) at Coldstream Mains, Coldstream, Berwickshire, is the first farmer in Scotland to put variable fertiliser application into practice using the Bogballe Calibrator 2002 Spreader Controller in conjunction with the SOYL-OPTI on a twin-hopper system.

Precision farming specialist company Soyl claims to have achieved compatibility between the two systems and increased farmer access to this technology. Previously, Soyl has only used the LH Agro 5000 Controller to regulate fertiliser spreaders.

Accurate distribution

The Bogballe Calibrator 2002 is purpose built to control the KRM EX spreader used at Coldstream Mains. The front- and rear- mounted twin hoppers are said to be achieving fast and accurate distribution of fertiliser on rates calculated by the Soyl system.

"We have saved 22% on our phosphate and potash inputs this year – thats worth around £2000 based on an average saving of £8/ha," says Mr McGregor. "On one field, where P and K would usually cost £37/ha by blanket application, weve only spent £20/ha with variable spreading.

"Several years on, when we know that we have been variably applying exactly the right amount of P, and K and we know that the pH and the magnesium are at the right level, we will be able to narrow down the reasons why some parts of a field are not performing as they should."

To enable Mr McGregor to undertake contract spreading this spring for Soyls Scottish distributor CSC Crop Protection, a £20,000 investment has been made in the KRM EX twin-hopper fertiliser application system with two sets of controls as well as the GPS (Global Positioning System). So far 270ha (648 acres) have been spread under contract.

Coldstream Mains, run as three blocks of land, grows winter wheat, winter barley, oilseed rape, potatoes and vining peas. All combinable crops were GPS yield mapped in 1996 for the last time.

Since last autumn 243ha (600 acres) has been GPS soil nutrient mapped in preparation for variable rate fertiliser application. The farms entire arable acreage will have been soil mapped by the end of this year.

"We have yield mapped for two years but it could take between five to seven years before we can draw worthwhile conclusions – mainly because of the variability of the seasons and crop types," explains Mr McGregor.

No margin for error

"There is far less margin for error with soil mapping. I believe we would see a very similar map if we were to sample the field again in one year whereas two harvest yield maps can vary considerably."

CSC Crop Protection agronomist John Strawson says the system enables farmers to gain accurate information to achieve the most efficient use of high cost inputs.

"Precise application of fertiliser is the key to efficient use and saving on inputs. Farmers using the SOYL system have been very impressed by the reduced costs of P and K applications.

"Savings of £8-£15/ha have been made, but the real benefit will be higher yields through improved nutrient status and reduced yield variability," says Mr Strawson.

Soil sampling, using the quad-mounted mobile computer as part of the Soyl-Mobi system, costs £20/ha (£8/acre), but the data forms the basis of variable spreading for the next five years thus reducing the annual cost to just £4/ha.

Simon Parrington, general manager of Soyl, says the companys liaison with KRM spreaders has achieved compatibility between the KRMs cab-mounted Bogballe calibrator and the Soyl-OPTI system.

"The application map is loaded into the OPTI which uses the GPS to locate its position on the application map. As the position changes the OPTI tells the spreader what rate is needed and the variable application is achieved.

"We believe this compatibility of systems is a major step forward and will open up precision farming technology to many more farmers," says Mr Parrington. &#42

Soil nutrient mapping has enabled variable rate fertiliser applications to be carried out at Colin McGregors Borders arable farm.

Colin McGregor (left) discusses soil nutrient maps with foreman Ian Robertson.