Food is a province-level resource that is required and consumed by pops and along with population capacity is one of the main constraints on how large the population of a territory can grow. While food is not a significant concern at the beginning of the game, as cities get larger they will begin to outstrip their local food supply, requiring investments in production infrastructure and trade routes to sustain. Armies will consume food when outstripping the local supply limit or when operating in hostile areas, requiring management of their food supply to ensure that soldiers are being properly fed during a campaign and avoid the crippling attrition that comes with running out of food.
Production and consumption
Food production is determined at the territory level, with the base production of a territory determined by the sum of its local monthly food modifiers. All territories have a baseline level of food production determined by its terrain, ranging from +4 food for farmland territories to +2 food for deserts and mountains. There are also small bonuses to monthly food in country and province capitals. This is generally sufficient for most provinces in the early game and for those that do not see significant population growth, but even a province full of farmland territories will eventually not be enough to support a large capital city. Notably, this baseline level of food production is not dependent on the number of pops in the territory.
The other major contributor to monthly food is with the food trade good bonuses. Each instance of grain present in a province gives +5 food, while of the other food goods fish and livestock give +3 food each. These trade goods can be accumulated either from importing trade goods, which takes up an import route slot, or from local production within the province, which is generally limited by the number of slaves that can be sustainably kept inside the food trade good-producing territories (i.e. because of population capacity limits). Therefore, the most food-rich capitals will be those in provinces capable of producing the most food trade goods, typically those with many food trade good-producing settlements - ideally grain, but in general any food production is still highly advantageous - particularly on farmland, as farmland territories have a base surplus threshold bonus that stacks particularly well with farming settlements. Like with all trade good surplus modifiers, the food production from trade good surpluses is technically applied to the capital of the province, which means that it is additionally affected by any monthly food modifiers there.
The base food production for each territory is also modified locally by the local monthly food modifier and country-wide by the global monthly food modifier, which can as much as double the base food production when maximized. Food production modifiers are a common deity and omen bonus and are available from certain inventions ( Civic and Religious) and other modifiers, and can also be increased locally with the Encourage Trade governor policy, salt, honey, and vegetables trade good bonuses, the slave estate and farming settlement settlement buildings, and the forum city building. Colder northern and alpine territories also have a permanent food modifier malus to represent the relative difficulty of growing food in harsher climates. Finally, blockades, sieges, and occupation give maluses to the related total food multiplier modifier, which also affects the food produced/consumed by a territory, significantly decreasing food production and possibly becoming a serious problem for the population if it drags on for too long.
Food is added into and consumed from a province-wide pool, which means that a food deficit in one territory can be made up for by a surplus in another territory. There is no way to move food or food production from one province to another, except indirectly by trading food trade goods.
Every pop consumes a certain amount of food according to its class:
- Nobles: -0.5 food per pop
- Citizens: -0.3 food per pop
- Freemen: -0.2 food per pop
- Tribesmen: -0.1 food per pop
- Slaves: -0.1 food per pop
Therefore in addition to their larger number of pops, the high noble and citizen ratio of cities contributes further to their high food consumption.
Monthly food surpluses or deficits goes into the supply of province food, which allows a province to store extra food during periods of higher production as a buffer for when the food balance falls into deficit. The monthly food production balance is the way that the province food supply can grow or shrink, though there are also various events and missions that interact with it. Province food is always capped at the province food capacity.
For every 12 months of total food consumption stored, up to a maximum of 120 months (i.e. 10 times), a province will get the following modifiers:
This means it can be advantageous to increase the food capacity in order to be able to store enough food to get the modifiers even if the province realistically does not need that much stored food, though this becomes increasingly expensive and unfeasible for larger and more populated provinces.
Running out of food is a very serious situation that will cause massive unhappiness and unrest in a province. If the food in a province drops to 0, the province will get the Critical Food Supply modifier, giving:
- +5 Minimum Unrest
- +5 Local Unrest
- -75% Total Population Capacity
- -25% Supply Limit
- -50% Local Fort Defense
In addition, every territory in the province will get the Population Dying modifier, giving:
Both of these modifiers stack, and the large drop in population capacity will usually have a very large impact on pop happiness, further exacerbating issues with unrest and province loyalty and giving a severe impact on local population output. The combined effects of these modifiers and resulting overpopulation will also result in pop death and significantly increased migration away from the province and so a lack of food supplies will usually eventually resolve itself, though not before inflicting significant economic damage and possibly triggering rebellions.
There is a Low Food Supply warning that appears if any province drops to below 100 food - if the alert appears, it is usually a good idea to look into resolving the food supply issues of that province. Province food cannot go below 0, even if the province is still consuming more food than it produces while having no more remaining food stored.
Every province has a province food capacity that determines how much food it can store. Every territory provides a base of +100 food capacity, which can be further modified locally by the provincial food capacity modifier and country-wide by the base food capacity modifier. As the cap on provincial food, it usually determines the magnitude of a province's stored food bonus. The easiest way to increase food capacity within a province is to build granaries in the province's cities; it can also be increased country-wide by certain deities and the Grain Stockpile national idea.
Each army has its own supply of stored food and maximum food capacity. Each cohort contributes a certain amount of food capacity, typically only around 1 to 2 years' supply of food (less for heavier unit types, especially war elephants) with the exception of supply trains, which are very weak in combat but have a very high food capacity per cohort. Any army that is expected to be involved in sieging or operating in enemy territory for any significant length of time should have enough supply trains to sustain themselves, which in particular means that smaller levies that do not come with a supply train are generally unsuitable for these sorts of extended operations.
An army consumes food if it is in enemy territory or taking attrition, either because it is in a province with a supply limit that is too low or has a baseline level of attrition. Each cohort has a baseline consumption level based on its type, which is increased by 10% for each point of attrition it is taking. If an army runs out of food, it will begin to lose soldiers from attrition, which rapidly ramps up the longer an army goes without food and can completely wipe it out if left unsupplied for long enough.
The food supply of an army is replenished if it is either in friendly territory or in a controlled enemy territory whose province capital is occupied, and the province has stored food to resupply it with. An army will always replenish 1/12 of its food capacity each month, as long as there is enough stored food in the province; this means that it is possible for an army to be sustainably placed in territory where it is taking attrition, as long as the food supply of the province is sufficient to resupply it. Note that it is possible and common for armies to consume more food than a province's net food balance, which can eat into its stored food and potentially make it run out, though once the food supply reaches 0, the army will stop resupplying and allow the food supply to rise again for a month.
While levies are raised and mercenaries hired with their food capacity full, legions cohorts are recruited with only a small amount of food, and so take a few months before they will fill up their food capacity. Armies that are merged will sum their stored food together and splitting the army normally will also divide the food as possible, except with the Detach Support action, which will leave most of the food with the army rather than the supply train. This makes it feasible when sieging to detach the supply trains, send them back to friendly territory to resupply, and then return full of food to ensure that the siege can go on without having to move the actual army back and forth to resupply.