APPENDIX C 

 METHODS OF LAND CLASSIHCATION 



The USDA Soil Conservation Service uses a Land Capabil- 

 ity classification which involves the grouping of kinds of soil 

 into special units, subclasses, and classes according to their 

 capability for intensive use and the treatments required for 

 sustained use. Eight land classes are used. Arable soils are 

 classes I through IV, classes V through VIII are nonarable. 

 The classification is based on a 5-foot profile. Class I is not 

 used in \lontana due to climatic limitations. 



The Bureau of Reclamation uses an Irrigation Suitability 

 Land Classification. Its primary purpose is to characterize 

 the lands suitable for sustained, profitable irrigation agricul- 

 ture. Soil and related features must be correlated with eco- 

 nomic factors. Soil investigations may be to a depth of 10 

 feet or more. Arable soils are classes 1 through 3, Class 6 is 

 nonarable. 



The Montana DNRC uses a Land Classification that has a 

 format similar to the Bureau of Reclamation Land Classifi- 



cation. The specifications resemble those of the Soil Conser- 

 vation Service Land Capability Guide. Arable soils are 

 classes 1 through 3, Class 6 is nonarable. 



The RWRCC Land Classification Specifications for Irri- 

 gated Land include some features of the other systems. It also 

 includes additional soil properties and related features such 

 as moist bulk density, surface and subsurface drainage, etc. 

 It was designed to provide documented specifications for 

 the classification of irrigated land and its suitability for 

 sustained production under irrigated agriculture. 



Class rV used by the Soil Conservation Service is very 

 restrictive and will occur in Bureau of Reclamation, DNRC 

 and RWRCC classes 3 and 6. There will also be some overlap 

 in other classes when the different classification systems are 

 used. This in part helps to explain the difi^crences for arable 

 and nonarable acres between the various systems. 



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