Which term is often used to describe a region with rich agriculture?

The term often used to describe a region with rich agriculture is "fertile." This term specifically refers to land that is capable of producing abundant crops due to its nutrient-rich soil, adequate moisture, and favorable climatic conditions. Fertile regions are typically characterized by their ability to support a variety of agricultural activities and sustain diverse plant life. Good examples include the Nile River Valley or the Central Valley in California, where fertile soils are instrumental in high agricultural productivity.

In contrast, the other terms do not accurately capture the essence of a region ideal for agriculture. A desert typically refers to arid, dry regions with limited vegetation and unsustainable conditions for agricultural growth. A plateau denotes an elevated flat land which can have varied vegetation based on climate but isn't inherently associated with rich agricultural land. Lastly, barren suggests land that is devoid of life or unable to produce crops, making it the opposite of fertile. Thus, "fertile" is the term that best embodies the richness required for robust agricultural practices.