A set of config options called "Manure softcap" and "Manure softcap penalty %", that would work roughly as follows

on eggLayedEvent
if amountOfManureInNest > manureSoftCap then
eggProducedChance = hatcheryEggDropRate% - manureSoftCapPenalty%
timeToNextEgg = chickenGrowthTime + manureSoftCapPenalty%
endif

so basically if you have the softcap set to 10 and penalty to 20, then if a nesting pen has more than 10 manure in it then it has 20% less chance to produce an egg/resource when the timer runs down and then when the timer resets it takes 20% longer for the next cycle.

Possible split the time and chance penalties into two separate values.

that't a pretty neat idea I will take it into consideration. Thanks