I have 4 groupings of farms. I got better at balancing them as I went:
A: 5 imp farm, 6 imp silo, 1 field:
B: 6 imp farms ,6 imp silo, 1 silo, 1 field
C: 4 imp farm, 4 imp silo, 1 field:
D: 5 imp farm, 5 imp silo, 1 field:
My goal was 1:1 imp farm to imp silo ratio where the farms can be buffed, but the silos do not need to be. I succeeded in groups C and D but had to add an extra imp silo or silo on A and B, respectively.
All this plus the epic farmyard produce 38k wheat per 12hr:
(apologies for the lighting...the Sandman visits my island regularly )