How do refrigeration and improved transportation affect the von thunen model of land use?

They make it obsolete because perishable items now can be grown farther away from the city center.

Explanation:

Von Thünen was responsible for introducing the spatial dimension into problems of an exclusively economic nature. Through its model of agricultural land use, based on a system of mathematical equations, it was possible to arrive at a static equilibrium model of the distribution of agricultural activities in space.

This model is based on a hypothetical situation in which the production of agricultural products must be distributed on an isotropic plain, isolated from the outside world, with constant production and transportation costs and which has a single consumer market located in the center, so that maximization of profits from agricultural production. Though revolutionary, this model became obsolete with the creation of refrigeration and improved transportation because they allowed perishable items to be grown farther from the city center.

associative property of addition