This soil farm has the ability to raise the biomass of the body it is on. This process doesn't affect any other terraforming statistics.. Levels beyond V are only reached through events.
"A few plant species will be able to live in the local dirt as-is, but most will require the sort of bio-rich soil they would find back on Earth. Eventually those sort of soil will be produced naturally by the biosphere, but we can get a jump on the process by manufacturing soil manually and introducing it into the environment." - Ingame Description
Beginner Mode differs in time needed compared to Normal Mode. The Culture modifiers accounts to the total Biomass, Population, Credits, Research Time and/or Construction Time gained/lost for the buildings/research.