The study upon which the land quality variable is based was initiated as a result of the authors' work in developing data for the Economic Research Service's Land Inventory and Productivity System (LIPS). A search of the literature revealed a void in published data concerning the productive relationship of water, fertilizer, and other inputs, to land as a companion resource for the production of agricultural goods. The LIPS data presented an opportunity to estimate production relationships which incorporate certain physical characteristics of the land resource to aid in the identification of the relationship of water and fertilizer to yield.