Hi,
I was just looking at your document. Some recommendations and comments below:
Organic pesticides
Nothing like that really exists. The closest thing to organic pest treatment is to find something higher in the food chain that keeps the usual pests under control.
I would replace it with concepts of monoculture vs polyculture
Should organic products be indicated with an icon?
In modern user interfaces it would be called an overlay or decorator - a little image overlaying the main icon. You might have seen that on the folders synced with Dropbox or similar. It should look a little like these:

- corn-no-gmo.png (32.29 KiB) Viewed 5218 times

- corn-organic.png (32.8 KiB) Viewed 5218 times

- corn-gm.png (30.68 KiB) Viewed 5218 times
I would say, all these decorators are necessary, and maybe the city major might decide if "contains GMO" labels would be mandatory; while the "contains GMO" flag should progress into food products that used them, the "100%organic" one will be lost if any other food component in a product does not have that flag.
each of the labels might have a variable malus/bonus to the unlabeled ones depending on events like a food scandal or a farm accident or so.
Fertilizers -affect crop quality and the yield
Pesticides – affect the yield
Pesticides affect quality too - negatively if used too much.
Yield – new formula:
crop yield (the qty of crop harvested in each harvest)
= pesticides quality * 70% + fertilizer quality * 30% + rainfall
how complicated would it be to apply a sigmoid function on pesticide and fertilizer input?
I would change the formula into
ideal conditions yield (tons/ha) * farm size * soil fertility factor * present pests factor * growing period weather factor
soil fertility factor is a number of 0-1 where 0 is desert and 1 is a meter of fertile soil. With each harvest it drops by 1%. This drop can be reduced/negated by adding compost/manure/mineral fertilizer, or have a cover crop on it. Applying mineral fertilizers products would cause to lose the "100% organic" flag on its crops for the next 5 years.
present pests factor is a negative sigmoid function between 1 and 0 where the size of the farm, the years of growing a single crop and the application of pesticides/pest control are contributing.
weather factor is calculated weekly/monthly accumulatively - 1 would mean the whole growing period the weather conditions were ideal. Impacts can be too cloudy, not enough rain, too much rain, extreme weather events, where the latter one can easily destroy 90% of a harvest.
Some types of crops can only grow on land with fertile soil
nothing really grows where soil is not fertile. It would be better to turn this into a
soil acidity property.
Here is a table about different crops and ph ranges:
https://harvesttotable.com/vegetable-cr ... olerances/
transport them throughout the country to supply them to all of the people at a reasonable transportation cost
I would not bother in this DLC about transport - this is a whole different story about providing specific vehicles and ships and planes for different goods, hiring transport companies etc...