Efficiency analysis: ideal combos
First things first: notice that each and every crop requires three different nutrients at various levels, but the requirement always sum to 0: nutrient-wise, farming is a zero sum game. See it another way, plants *transform* one nutrient into another, never really producing a nutrient. As a result, it is *impossible* to have a spatial or temporal combo that purely *produces* any nutrient as a net result. For those who prefer fancy talk, we can prove this by using the property of a matrix there row rank equals column rank.
To keep things easy, we want to not rotate over time, but only over space (within a single farm plot tile), so you can keep sowing and reaping the same thing over and over again.
Below are combos that I (and others, most likely) found, ordered from most viable to least viable. All of them are perfectly balanced: they do not consume nor produce nutrients. If plotted with proper configuration, they will always meet family requirement and produce Giant results.
You can use any configuration of plant location that satisfy family requirement, following the ratios shown in the tables below, not necessarily 4x4 at all. I'm using the following grid: 1 tile 4x4 crops:
Any combos with 2 or 4 varieties below can be used with this 1 tile 4x4 crops setup. Combos with 3 varieties can simply ignore one corner to keep it balanced, or rotate that single block over time. This 1 tile 4x4 crops is currently only possible with the Snapping Tills mod by surg: https://steamcommunity.com/sharedfiles/filedetails/?id=2302837868
Nutrient requirement and equinutrient replacements
In any season, there are a few plants with the same nutrient requirements, thus can be used as a replacement for each other.
Autumn replacements: Carrot=Pumpkin, Potato=Eggplant
Winter replacements: Carrot=Pumpkin
Spring replacements: Potato=Eggplant, Corn=Asparagus, Onion=Pomegranade, Dragonfruit=Durian
Summer replacements: Onion=Pomegranade, Dragonfruit=Pepper.
Unique nutrient requirements with no replacement anytime: Garlic, Tomato, Watermelon.
Full table sorted by seasons availability and nutrient demand similarity:
WIP: I'd rather paste text instead of images. However, I need text to use a monospaced for the tables to be properly formatted. However, using monospaced in this forum seems bizarrely complicated. Still figuring out. Let me know if you know how. Until then, I'll just paste in screenshots...
Technically, you could replace Pumpkin with Carrot, but why? Unless you are going after bunnies...