Global commodity prices for the country's exports have fallen for the sixth successive month.
The ANZ Bank's monthly Commodity Price Index declined by 3.3 percent in August, compared with the previous month.
It is now 12 percent below the record high in February, and back to the level of 17 months ago.
Dairy prices, which makes up 47 percent of the weighting in the basket of 13 commodities, fell heavily, while the prices of pelts, apples, kiwifruit and sheep meat also declined.
In contrast, beef was up by 13 percent to a new record high, while aluminium rose to an 18-month high.
Returns to commodity producers fall by 0.4 percent last month, and by 12.5 percent for the year.