MANAGING CROPS according to field soil variations makes economic and environmental sense, says Duncan Lee.

Manager on the 2000ha (4950- acre) Ramsbury Estate in Wilts for three years, he warmed to the Courtyard idea after working with a more sophisticated system in a previous position.

“That idea was fine, but too intensive and probably provides you with too much information. Certainly that sort of precision for P and K is illogical. It’s not cost-effective,” says Mr Lee. Ramsbury’s 1700ha (4200 acres) of arable is mainly on chalk downland with clay cap.

Saving on nutrients is not the sole reason for identifying soil changes, reckons Mr Lee. “I am interested in soil-based seed rates. For example, we usually need to lower them in the valleys and up them on the clay cap.”

It may become necessary to move to GPS-driven agronomy, he acknowledges. But for now, with about 30% of the land assessed and analysed, he is content to continue with Mr Gillingham’s map-based system using a standard Kuhn 24m spreader.

“It’s a step forward in trying to justify a full GPS system.”

Its standard analysis has already picked up big differences in soil nutrient reserves between the “invisible” fields, he says.

“We’ve had P and K indices from 1.5 to 4. We use quite a bit of sewage sludge. So now I’ll probably apply it more to the low P areas.”

The Courtyard system should also permit prilled lime to be adopted to correct pH levels more precisely, he believes.