"Research Field"

[Davadin]

In the Nature Sciences Research Topic Header, research item "Food Sciences" says it gives +1 Supplies for each mastered "research field". What is a research field, and how does one master it?
(To clarify- it's my first play-through, and I'm trying to figure out what some of the terms mean.)

[xploring]

I think mastered research field means you complete a research tree. Usually you can only get 2 done after the 4th expedition.

[Flamestalker]

There are six research fields: Observations, History, Anthropology, Psychology, Engineering and Nature Sciences. What "Food Sciences" looks for is how many of those fields you have completely mastered (done all the research papers in that section). Like kcyw said in an average game you generally only have enough research to completely master two, though with a heavily research focussed build you can complete a third one.