An Improved Economic Land Classification System for Spatial Linear Programming Models

require establishment of a land resource base so representative enterprise budgets can be constructed Economic Classifications to reflect productivity and limitations of each Whittlesey [15] used the land capability classes region's agricultural land. To relate the land base to of the Conservation Needs Inventory (CNI) [11] to budgeting procedures requires an economic classificaestablish three soil quality classes for use in a spatial tion of agricultural soils. Ideally, this classification linear programming study containing 144 production would group together those soils requiring similar regions. Eyvindson [1] used this same procedure in a cultural practices and having the same yield capabililater study. ties. Costs and returns can then be computed for The CNI is an ongoing national project to selected agricultural enterprises within each classificaprovide information on land use and conservation tion. Technical information on agronomically based treatment needs on a county basis for each state, soil classifications is available through agricultural Puerto Rico and the Virgin Islands. Soil data are experiment station reports and the Soil Conservation grouped into capability classes and then subclasses. Service. These reports give an abundance of detailed There are eight capability classes which depict prophysical and chemical soil data on a county basis. gressively greater limitations for agricultural producBecause technical data are extensive, a problem tion and fewer choices for cultivation. Subclasses exists in translating this information into economic indicate problems such as erosion or runoff, wetness groupings suitable for use in constructing budgets. and drainage, root zone and tillage limitations and Economic classification of soils for a spatial study climatic limitations [11]. should be pragmatic but detailed enough to ensure a The CNI provides consistent data across regions meaningful linkage of enterprise budgets to the soil. but presents difficulty in developing enterprise budThis paper outlines an improved procedure for gets, because detailed land use data and conservation grouping agricultural land data for regional analyses. treatment needs are available but no link to various This procedure conforms more closely than other soil types for a specific area is given. related groupings to the most current agronomic soil In a later study, Nicol et al. [5] made comclassification, and is flexible enough to be used in mendable improvements toward an economic classifienterprise budget formulation for more than one cation in a national spatial model. Basically, yields for specific region. The next section briefly evaluates soil the most productive land class in an area were delineation criteria reported in selected studies. A defined. Ratios for each class were defined relative to discussion of current soil classification in the United these yields. These ratios were used in developing States is then presented, followed by the proposed another set of ratios to relate land class to area method of using available land classification data to average yields. form agricultural land groupings appropriate for Shumway, et al. [9], in a spatial model for