Which region is Russia's most valuable to farmers?

Land that is near/at the center of Russia but lower in the center because the south have more heat than the north

Tundra refers to the generally cold climate of the Earth’s northern hemisphere. ‘Â Areas that have a tundra climate have average temperatures of lower than 5 degrees Celsius. ‘Â Characteristic of tundra climate is the soil condition called "permafrost". ‘Â This condition literally means that the soil is permanently in frost mode. ‘Â This condition makes it a very harsh environment for various plant and animal species.