Also, the run-up of grain prices over the course of the year reflects not grain getting eaten up, as I'd assumed, but costs (and especially the opportunity cost) of storage? Wild, but it makes perfect sense: why *shouldn't* peasants smooth calorie consumption throughout the year?

If there's a bad harvest, then-- assuming zero cost of storage-- we should see calorie consumption reduced uniformly throughout the year. Actually, here's a paper: do dramatically falling interest rates in rural Poland during the '20s result in a flattening of grain price runups?

The grain price data emphatically exists to test this. The interest rate data may be a bit trickier (since we are talking about the informal market, far, *far* above the legal usury rate) but I'm sure there's something.

As a first cut, we don't even need interest rate data: we can use the large differences in financial market sophistication between Polish regions (much better in the former Prussian part than out in the Kresy), and there are good proxies for this.

Perhaps even some regression discontinuity relying on different legal systems between provinces that aren't made fully consistent until the early-mid 1930s. We definitely, 100%, have grain price data that's disaggregated enough to do this.