Using Airtable to generate a "recipe"

That's a bizarrely framed title, but I'm unsure how to surmise..

Here's what I'm trying to do:

I run a garden. We have 3 different nutrition programs, that use a different mix of ingredients, and share some ingredients. The amount to make depends on how many m2 are to be treated (or how many L of water are used to drench seedlings).
These programs are:

1. Foliar 1 (mixed for m2)
2. Foliar 2 (mixed for m2)
3. Transplant Drench (mixed to vol of water used for seedling drench).

I need to keep records for our organics certification on what inputs are used, and when and where they are used.

So I want the user to be able to select "Foliar 1," input how many m2 of garden they are treating (or how many L of water they are using to drench seedlings). I then want Airtable to "generate" the quantities of each input they need, without needing to do any potentially confusing math. 

It can store that as a record against the date, so I can archive that.

I currently have an "inputs" table, which has the name and rate/m2 or rate/10L of water (2 different fields). 

But I am getting lost on using this info to create a recipe. Does anyone have any guidance to get me out of the creative rut?