Farmers are looking to "turn things on their head" by challenging environmental assumptions about their sector at a water forum tomorrow.

In a hard-hitting public statement, Spierings described media comments by the Feds as "disappointing", "inaccurate" and "puzzling".

A fall in global commodity prices and the strong kiwi dollar meant New Zealand producers were squeezed in the first quarter.

Prices have plunged overnight in the latest world dairy auction, falling to below the 10-year average for the first time since 2009.