Can food continue to outperform crude?
Up until last year, prices of food and crude oil had moved largely in tandem, according to Bank of New Zealand, flagging a "strong relationship" between the two.
"For those who like formality, the correlation coefficient since 1990 is +0.92 and an even higher +0.94 for the period since 2000," said the bank, taking monthly data from the United Nations Food and Agriculture Organization as the basis for food values.
The link between energy and ag values, which the bank said "is probably as old as the horse and cart", reflects factors including the growing use of crops in making biofuels, and the importance of oil and its kin as an input cost for farms.
"Lower energy prices encourage more food production, other things constant," BNZ, with the extra output implying lower ag values too.
Meanwhile, lower crude prices "reduce oil producers' ability to pay for food" too, a factor which has been noted, for example, in the Russian market (albeit with the impact clouded by the effects of sanctions and counter-sanctions).
Still, the price link has broken down a bit since late 2014, with the slide in oil prices outpacing the drop in food values.
"Food prices have significantly outperformed oil over the past year and a half," BNZ said.
"It probably doesn't feel like it from a food producer's point of view given the decline in food prices. It is just that food prices haven't fallen as far as oil prices."
The shift has driven the price ratio of food to crude oil, which for the vast majority of the 2005-2015 period stood "in the low 2s" back above 4.0.
The ratio has not stood above 4.0 for a sustained length of time since the 1990s (when it topped 10.0 at one point).
"It will be interesting to see how this ratio progress from here," BNZ said, if stopping short itself of making any prediction.
"Will it return to the low 2s from the 2005-15 era? If so, will it be via lower food prices or higher oil prices or a combination of the two?"
And its point on the energy-food price correlation is not lost on brokers.
"Until energy prices find a bottom… it's difficult to see our space mounting a sustained recovery," said Tregg Cronin at US grains broker Halo Commodity Company.
Still, at least, for crop bulls, energy prices are reviving, for now at least.
On Monday, oil futures stood at $34.09 a barrel for Brent crude, extending their revival from the multi-year low of $27.10 a barrel reached on January 20.
And the recovery in energy values may already be helping boost grains demand, driving ethanol values back to a discount against gasoline in the US.
"The RBOB [gasoline]/ethanol spread was breached on Friday, allowing ethanol to be seen as a discount to RBOB again, putting somewhat of a positive spin on refining competitiveness," broker CHS Hedging said.
By Mike Verdin