Where to build markets - only in fertile lands?

[al Roumi]

p.s. Does it not seem odd that Hyuga, which specialises in farming, is also a barren province?

From your link, a province with farming specialisation means you can build an extra level of irrigation on its farms, presumably creating +5 food in that province.

I think Dead guy is right that food is based on the development level of your farms (i.e. 1 to 4), rather than the fertility of the soil -which governs the financial output of the farms.

You do at some point have to weigh up where your food will be distributed and how -essentially: castles or markets?

I don't think that a focus on self sustaining provinces is going to be the most productive/performing. Tuning a system of recruitment/trader and feeder provinces is surely the way to go. Higher level castles bring greater benefits as recruitment centres but also stronger defensive positions (if only mainly by spawning dedicated defensive units when besieged). As for markets/rice traders/merchants guilds they add a bonus to a region's trade, so its clear they should be built in your trading centres.

I guess the next logical (or meticulous/analy retentive) thing is to plan your conquests and developement around how much food you will have available from your target provinces. This way you can share out castle and market development with a little coordinated forethought, a bit like the old trick from civ4 of planning city placement around the "fat cross" and what resources/features will be included.