Plains give +1500 growth and can be considered "op"

[tyggerr]

In the structure.yml farms have a 15 bonus growth on plain, but plains give 1500 bonus growth instead.
That's because in FarmChunk you have (Line 241 and 251 respectively) :

effectiveGrowthRate = (double)this.town.getGrowth().total / (double)100;
effectiveGrowthRate += ab.getValue(); ///// + 15

So you take your town growth, let's say 1000, you divide it by 100 and end up with 10. However, if you are in a plain you add 15. So 15 is like 1500 town's growth, which means having a plain in a 1 growth town is like getting +1500 growth directly.

[ataranlen]

Just to clarify the growth rate is a little wonky in its calculation.
A farm has 252 possible grown spaces.
The farm.grows_per_tick is 6.

If a town has a growth rate of 1000 base(Really high), it will grow 60 spaces per growth tick.
With a plains, that becomes 150 per growth tick.

int crops_per_growth_tick = (int)CivSettings.getIntegerStructure("farm.grows_per_tick");
int numberOfCropsToGrow = (int)(effectiveGrowthRate * crops_per_growth_tick); //Since this is a double, 1.0 means 100% so int cast is # of crops
int chanceForLast = (int) (this.town.getGrowth().total % 100);