How many days worth of food is a standard/iron ration

I assume its one ration per person per day but i cant find anywhere where this is stated.

I would also like clarification on the encumbrance category on the ration-units. If we hold to the idea of 2 pounds solid food per day, then a week of rations would be 14 pounds of food, which is the upper limit on 1 stone. However, if the ration-units are just meant to be one day each, that sounds like it would put them in the "small item" category of 1/6th stone.

That ultimately makes a difference in terms of how much the rations weigh. If one day of rations is 1/6th stone, then a week of rations would be 1 stone and 1/6th. But if the base unit is a week of rations and it's 1 stone, then that's a little lighter than the alternative.

The price listed is for Rations, Iron (one week.) Ergo, I would assume that it's for a week's worth of food, and weighs one stone.

LOL yeah I should of noticed the one week on the table, o well thanks. That being said I assume its one week of food for 1 person but is this actually stated anywhere in the book? I realize that because of the weight it has to be for one person only but is it listed anywhere that its for one person or are you just supposed to assume it from the math? And another question for demi human and beastmen characters do they eat different amounts of food? 

On a related note how hard should it be to find water in ruined farmland? An area not near any rivers that relied on aqueducts but most(not all) of those were destroyed recently.

Not an Autarch, just the grandson of farmers - as long as there isn't a drought, water is actually really easy to find, even in abandoned farmland. Farmers dig water-holes for cattle and other animals, or for simple water storage; these capture rainfall and feed the nearby water table. Even without rivers or aqueducts nearby, there are bound to be mudholes, waterholes, and ponds nearby. If the destruction were recent (or there were recent rains), even ponds high above the water table would still have water in them.

Imagine a week of rations as a bundled item of one stone. Once you use the first one, the remaining 6 are loose and just as unwieldy as the original week of rations.

I like easy-to-track supplies, so I don't really worry about them unless they're likely to impact the story. Maybe my players are headed out into harsh wilderness or planning an extended dungeon stay.  In fertile areas I track rations at one item per person per day (water is easy to find and mounts can graze). In harsh areas like desert, this becomes 1 stone of supplies per person per day (1 item of food and 5 items of water), and 4 stone per day for each horse-sized pack animal/mount. Camels are an exception of course. Camels are awesome.

Per Arman's note, water can more-or-less be ignored except in desert or barren terrain.

When you DO have to worry about water, though, it's a big deal. The massive weight of water is why the supply range of armies shrinks so rapidly when dry terrain has to be moved through - the water that the pack animals must carry to make the trip exponentially increases until it consumes the entire load.