19 August 1997

Brassica N system can pinpont needs for range of crops

Last weeks Vegetable Focus event at HRI Kirton, Lincs, saw a host of new advice and products for field veg growers. Edward Long reports the highlights

A SYSTEM developed to accurately target nitrogen applications to actual needs of leafy brassicas is being extended to mainstream arable crops.

Brassica growers can now use the Well-N prediction model, which was developed with HDC funding by HRI Wellesbourne, to ensure strict production protocols are not breached by excessive or unnecessary nitrogen.

HRIs Clive Rahn says a third of the UKs cauliflower crop may be given unnecessary and wasteful amounts of N. This increases the risk of lodging and disease, delays maturity, and adds to nitrate pollution pressures.

"Currently many growers are still putting on a traditional amount of N regardless of whether their crop needs it or not," Dr Rahn says. "This is both an unnecessary waste and potentially harmful to the environment. Well-N is geared to pinpointing where residual N can be exploited by reducing the amount of bagged N applied, and ensuring no crop goes short. This more targeted approach improves precision for modern production systems, and offers scope for cash savings."

The system does not always lead to N reductions. Last year an investment of £56/ha in extra N for brussels sprouts at HRI Kirton increased returns by £580/ha.

When calculating the amount of residual N available in soil the computer-based system takes into account target yield, geographical location, local weather, soil type, and fertiliser use on the previous crop.

In a joint MAFF-LINK project with IACR Rothamsted, the HRIs Well-N system is being evaluated for use with a range of arable crops.

Getting to grips with pest control – new threshold-based systems will help growers reduce pesticide use in line with supermarket demands, says HRIs Rosemary Collier. Advice packages are being tested now (see below).