I understand. I did the math some time ago on a separate forum. During the first 300 turns Commies net more per turn than any other govt, but farmers cash more per turn (that's selling each bushel @ $29). It's the fact that commies can only place 45% of their production on market for sale.

For those of you too lazy to read the entire post, the above information applies only to the first 300 turns and in the instance of a player looking to maximize INCOME (cash) during their first 300 turns with the intentions to change govt -farmers lead the pack.

It's really a matter of #s which can all be calculated:

Typical 300 turn setup [ BOTH GOVT M ]

3500 A
100 CS (30 BPT) sqr(3500/4) = 30
3400 Farms

3500A
100 CS (read above)
3400 IC

Farms formula w/ $29 bushel [[ Reference A ]]
3400*5.3*1*29(no market commission on private market) = $522580 per turn
3400*5.3*1*34*.94 = $575919
3400*5.3*1*39*.94= $660613

IC formula w/ $150 turret
'At 100% production, one industrial complex can produce: 1.86 (troops or jets or turrets), 0.4 tanks, or 0.62 spies.' [[ Reference B ]]
3400*1.86*150 = $948600 *.45 (maximum of 45% can go on market) = $426870 *.94 (market commission) = $401257
3400*1.86*140 = $885360 *.45 = $398412 *.94 = $374507
3400*1.86*130 = $822120 *.45 = $369954 *.94 = $347756

History on EXPRESS (turrets)
Aug 6, 08:00 Aug 6, 12:00 $144 $155 $155.00 4813
Aug 6, 12:00 Aug 6, 16:00 $135 $155 $143.08 253,544
Aug 6, 16:00 Aug 6, 20:00 $133 $140 $138.32 241,270

History on EXPRESS (food)
Aug 6, 08:00 Aug 6, 12:00 $45 $45 $45.00 7836
Aug 6, 12:00 Aug 6, 16:00 $44 $44 $44.00 20,621
Aug 6, 16:00 Aug 6, 20:00 $38 $40 $38.46 203,229

Factors not accounted for:
Production is 100% with 80% max population
Countries with ICs food production will be considerably higher per turn. [[ Reference C ]]

Reference A
http://wiki.earthempires.com/index.php/Game_Formulas

Reference B
http://wiki.earthempires.com/index.php/Talk:Buildings

Reference C
http://wiki.earthempires.com/index.php/Game_Formulas
(Pop * 0.03) + (Spies * 0.005) + ((Troops + Jets + Turrets) * 0.001) + (Tanks * 0.003)