Advanced Cultivation aims to diversify the farming experience in Rimworld. To this aim, soil has been reworked and composting and fertilizer have been introduced!

Overwritten Vanilla Ground:

Soil
Fertility: %70

Rich Soil
Fertility: %100

Marshy Soil
Fertility: %50
Dries to: Rich Soil

Gravel
Fertility: %45

Lichen-Covered Dirt
Fertility: %70

New Ground Types:

Tilled Soil 
Has %90 fertility
Requires the "Tilling" research
Only takes work to make!

Fertilized Soil 
Has %120 fertility
Requires no research
Costs 1 Fertilizer to construct

Enriched Soil
Has %150 fertility
Requires no research
Costs 1 Enriched Fertilizer to construct

Miracle Soil
Has %200(!!!) fertility
Requires no research
Costs 1 Miracle Fertilizer to construct

New Items:

Raw Compost
Requires the "Composting" research
Costs .25 nutrition (~5 meat) per compost
Can be crafted in batches of 5
Craft at crafting spot or butcher table

Fermented Compost
Raw Compost naturally ferments over time (10 days by default)
Compost Bins allow compost to ferment faster (6 days by default)

Fertilizer
Requires the "Simple Cultivation" research
Costs 5 fermented compost per fertilizer
Craft at a Butcher Table or Drug Lab

Enriched Fertilizer
Requires the "Advanced Cultivation" research
Costs 7 fermented compost per fertilizer
Craft at a Drug Lab

Miracle Fertilizer
Requires the "Miracle Cultivation" research
Costs 10 fermented compost per fertilizer
Craft at a Drug Lab

If you don't like the increased difficulty from the soil changes, feel free to modify the Terrain_AC.xml.