238 AGRICULTURAL INDICATORS. 



unprejudiced, availing itself of all sources of information, but based primarily 

 upon the relation of indicator vegetation to existing practice. The most 

 difficult problem would be that of a large, adequately trained, and high-minded 

 field force, but the rapid development of the Forest Service has shown how 

 this can be accomplished. 



Relation to practices. While land classification is based primarily upon the 

 division into agriculture, grazing, and forestry, other considerations must also 

 be taken into account. At the outset, it is particularly important that the 

 future as well as the immediate present be considered. Many areas which 

 are non-agricultural at present can be made available for crop production by 

 the development of a supply of irrigation water or by the draining of the soil 

 to remove the excess of alkali. On the other hand, the extension of agri- 

 culture into mountain regions on a considerable scale would threaten the 

 water-supply of existing irrigation projects. The maintenance of forests on a 

 scienti fie basis is more than a matter of the present demand for lumber and 

 fuel. Jt has a definite and often a decisive bearing upon the agricultural 

 possibi ities of the land in the adjacent valleys and plains. Moreover, ques- 

 tions of reforestation and afforestation enter in relation to agriculture and 

 grazing, and perhaps to climate also. While the use of land primarily for 

 agriculture excludes forestry or grazing on any considerable scale, tliis is not 

 true of the latter. Under proper safeguards, forestry and grazing can be 

 combined in practically all forest and woodland areas, as is the case on the 

 national forests. It is not improbable that the extensive sandhill areas of the 

 Great Plains region will some day be covered with forests of pine without 

 seriously reducing the amount of grazing, and in some cases with an actual 

 increase in the permanent carrying capacity. 



The greater returns from agricultural land and the consequent possibility 

 of supporting a larger population will always constitute a temptation to 

 classify too much land as agricultural. If classification could be carried out 

 only during drought periods, this tendency would be corrected. On the other 

 hand, it would be emphasized during wet years, such as 1915, when many 

 r^ons received 50 to 100 per cent more than their normal rainfall. As a 

 consequence, the classification of land as agricultural must be made with a 

 definite knowledge of the existing conditions of rainfall and temperature and 

 their relation to the usual variations of the climatic cycle. Moreover, it must 

 be recognized that it is much less serious to classify a potential agricultural 

 area as grazing or forest land than to classify the latter as agricultural. The 

 former merely involves an insignificant economic waste until the real possi- 

 bilities of the land become recognized, while the latter often results in recur- 

 ring tragedies due to the attempt to make a livelihood where it is impossible. 

 Hence, it should become a cardinal principle of land classification to rate as 

 grazing or forest land all areas in which it is impossible to produce an average 

 crop three years out of four. This would insure an adequate and permanent 

 development of agriculture wherever possible and would warrant the intro- 

 duction of scientific and economic systems of grazing, which would change it 

 from a game of chance into an industry. 



Proposed bases of classification. While soil and climate have been em- 

 ployed in connection with various desultory attempts at classification, the 



