240 AGRICULTURAL INDICATORS. 



tests of agricultural possibilities, the study of physical factors, and the cor- 

 relation of crop production and plant associations, the last being regarded as 

 the most important feature of the whole plan. 



The most extensive and adequate application of the proper principles of 

 and classification to the lands of the West has been made in connection with 

 the stock-raising homestead act of 1916. This is based primarily upon the 

 ndicator method, and the details have been outlined by Shantz and Aldous 

 1917). While the primary object is to classify the areas filed upon for graz- 

 ng homesteads, it has proved necessary to deal with the classification of 

 agricultural and forest lands as well. In this connection the latter are rela- 

 ively unimportant, but the recognition of lands for dry-farming is an essential 

 part of the plan. This arises from the fortunate provision that a grazing 

 homestead must contain areas on which it is possible to produce crops of 

 forage. As already indicated, the only drawbacks to the method arise from 

 an untrained personnel and the lack of sufficient time for adequate survey. 

 The correlation of the indicator types upon the basis of structure and develop- 

 ment would have revealed additional values, but the plan marks a great 

 advance in land classification and it is unfortunate that its application is 

 restricted to lands filed upon under the act. 



The indicator method of land classification.— As the above discussion makes 

 clear, practically all the effective proposals for classifying land into the three 

 main types, or for subdividing these upon the basis of crops or values, rest upon 

 the fundamental significance of indicator plants and communities. The 

 systems proposed by Clements, Pearson, and Shantz and Aldous, though 

 arrived at from three different angles, are practically identical so far as 

 essentials are concerned. They recognize the importance of actual practice 

 and experiment as well as of quantitative studies of soil and climate in defi- 

 nitizing the correlations of the indicator communities. The latter, however, 

 constitute the indispensable tool of the land classifier, since its use is as ready 

 as it is extensive and is limited only by its accuracy and sharpness. In the 

 hands of a well-trained field force, it would permit the proper classification of 

 all the unoccupied lands of the West within a period of five years. The 

 essentials of such a classification are further discussed in a later section. 



Use of climax indicators. — It is clear that the climaxes themselves furnish 

 direct indications of great value for land classification. Thus, grassland, 

 chaparral, and scrub are obviously indicators of grazing land, while forest and 

 woodland are indicators of forest land. However, these comprise all the types, 

 and a different method is necessary for the determination of agricultural land. 

 This may be furnished by actual test, by the measurement of factors, or by 

 the use of indicator correlations already established in other regions. As a 

 matter of fact, some kind of farming test can be found almost anywhere in 

 the West, in the driest deserts as well as at almost any altitude. The studies 

 of the last decade have made the application of indicator correlations almost 

 universal, and the measurement of soil and climatic factors has at least been 

 begun in practically every climax. As a consequence, it becomes a relatively 

 simple matter to use climax communities to indicate those grazing and forest 

 lands which are also agricultural, in that they yield a larger return from crop 

 production than from grazing or forestry (plate 59). 



