There was $47 billion of rural debt, he said. "It's right up there. We've been encouraged in recent months with better cash flows among farmers that they are giving that some attention."
As a result of the ratings downgrades, money could flow out of the country and the cost of borrowing could rise, Wills said.
"For a lot of farmers it'll depend on their debt levels but they'll win a little bit on the lower currency but it's going to cost them a bit on the higher interest rate. Some will get advantage, some won't."
A lower dollar could also push up some input prices. People often bemoaned the damage a fluctuating dollar could do, particularly in the export sector, when it was high, he said.
"But this is another good example why it is a buffer. So when the world's not looking quite such a good place for New Zealand, generally that currency comes down. That's the flip side."
European countries within the euro currency did not have the benefit of a fluctuating exchange rate to provide a buffer, he said.
"Their buffer is to cut costs, cut jobs, cut government spending and that hurts and that leads to riots in the street."
BNZ economist Doug Steel said the falling dollar was not good news if it meant trading partners were struggling.
"And if the world is going into a funk, as the risk seems to be, and your ultimate consumers are struggling, it's unlikely to be a good news story," he said. "But I think it highlights when the world does get a bit wobbly and risk comes off the table, which often sees the kiwi dollar fall as it is, that does provide some insulation to those world ills."
The dollar had already been well off its highs, he said.
"There is a chance that the Kiwi dollar falls further than world prices ... and in that sense it can provide a net positive to the export sector."
Global concerns were putting downward pressure on a range of commodities with some industries falling quite heavily.
"The question is whether food can hold up," Steel said. "It has been [holding up] relatively well to date."
