In the last few pages of the World Book there is a map of the Crownlands drawn in a similar fashion to the other regions shown earlier. On this map there are five bushels of grain in the northern areas, indicating that the Crownlands produces a lot of grain.
This makes me wonder why even though there seems to be a lot of grain farms very close to the capital, during Tyion’s time as Hand there was still a dire food shortage in King’s Landing which caused the people to riot?
Does the Crownlands not produce enough food to feed the 500,000 population of King’s Landing? Or was Tyrion not able to requisition the much needed food either because the lords of the Crownlands were being uncooperative (as you’ve pointed out numerous times), or perhaps given their location those areas were affected by the war (eg. Tywin’s foragers) and couldn’t effectively send shipments down to the capital?
First of all, those maps are terrible. They have the Mountains of the Moon on top of the Vale itself, for crying out loud.
But you raise a good point. I think it’s got to be the second two things. I think A. the northern Crownlands were holding back both men and supplies, and B. I think Tywin’s army was primarily supplying itself from that region, because no way you can feed ~15-20,000 men from the foraging of a few hundred.