The last decade will almost certainly be remembered as a golden age of agriculture in the United States. High global demand, a cheap dollar and bumper crops meant farming and ranching did better than many other parts of the economy. It was a welcome rebound for farmers and ranchers, who have worked through a lot of tough times.

Those record highs in farm income may have tempted folks to spend money instead of socking it away. If farmers and ranchers were like many other Americans, they probably would have done just that. But that’s not how most of us reacted. Sure, we may have bought some new iron, but much of that was a reinvestment in the business and was replacing some very well-used...