Quantity of farms too low on small maps
On 256x256 maps, I see usually 1-3 of each farm type (occasionally 4 or 5). Industry setting is 'high' in map gen.
1 or 2 of each type is an insufficient number when production values are low; it's not worth building routes to serve these farms.
Consider how smaller maps could provide more farms, and guarantee that they are densely clustered (see #4001 also).
I don't recall having similar issues on larger maps; seems to have large numbers of farms, densely clustered.