Soil fertility is an aspect of soil productivity that relates to nutrient management. Soil fertility relates to available nutrients in the soil, and the soil’s ability to provide nutrients – either through its own reserves or through added fertilizer. Good soil fertility is essential for crop production.
To see a map of the soil fertility index across the US, click here: https://foresthealth.fs.usda.gov/soils/Content/Downloads/The_Soil_Fertility_and_Drainage_Indexes_NRCS_poster.pdf