UPDATED 2.00pm: Farmers are asking for understanding from the urban centres of New Zealand as dairy forecasts take a tumble.

Fonterra has just reduced its forecast Farmgate Milk Price for the 2015/16 season from $4.60 per kilogramme of milk solids to $4.15.

North Canterbury Rural Support Trust chairman Doug Archbald wants the urban population to understand there's more to dairy farming than polluting rivers, and they're going through a really tough time.

Mr Archbold says they've set up some extra support for farmers, in case demand increases. 

The Cooperative says when combined with the earnings per share range of 45-55 cents, it would currently equate to a forecast Cash Payout of $4.50-$4.55 per kilogramme of milk solids to farmers after retentions.

Chairman John Wilson says global economic conditions continue to be challenging and are impacting demand for a range of commodities, including dairy.

He says the reduction in the forecast Farmgate Milk Price will be very tough on farmers.

New Zealand First leader Winston Peters says the problem is a focus on exporting the raw product, rather than adding value.

"Take infant formula for example, that business in New Zealand is up and in just three years is in control of the Chinese."