> We don't normally look at agricultural indicators like crop yields, arable crop land, rainfall, food prices, and commodity futures because agriculture's a small but critical part of the economy.

Not just that, but relatively few people (at least in the US; this might be different for other "developed" nations, and is probably very different for "developing" countries) are exposed to the agricultural sector on a day-to-day basis (even in rural parts of the US, for example), which means they probably don't have the intuitive understanding of the agricultural sector necessary to determine whether or not it's doing well. Most people in the financial sector (I'd assume, and have observed) tend to live and work as far from farms as possible :)

Agriculture's also pretty unlikely to be a useful indicator of recession (I'd imagine; I'm no economist) because people need to eat; whether you're eating a meal at a restaurant or a meal you cooked yourself, or whether you're buying fresh or frozen/canned, the underlying agricultural side of that supply chain is gonna be more-or-less unaffected (at least by the supply/demand curve jumbling; loan availability, real estate values, etc. can still negatively impact the ag sector in the same ways they negatively impact other sectors), if not moreso given the typical amount of land required to do farming/ranching at the scale necessary to make decent money from it (so i.e. excluding subsistence and/or recreational/hobbyist farmers).