126 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



been carried on for many centuries in the presence of alkali. The 

 data thus obtained have made possible definite recommendations 

 re<j;arding the crops best adapted to various types of alkali in the 

 United States. Laboratory experiments during the same period 

 have afforded much information concerning the relative toxicity of 

 the different alkali salts and concerning the influence of alkali upon 

 the utilization of soil moisture by i^lants. 



Success in breeding crop plants for dry-land agriculture depends 

 upon a thorough understanding of those features of structure and 

 function which enable plants to cope with a meager supply of water. 

 Recent field and laboratory investigations of the bureau have largely 

 cleared up the obscurity surrounding this subject. Adaptability to 

 dry-land conditions has been found to depend not, as has generally 

 been supposed, upon superior ability to extract water from a dry 

 soil, but, primarily, upon ability to manufacture a given quantity of 

 dry matter with a minimum expenditure of water. The results of 

 these physiological investigations are being practically applied in 

 breeding drought-resistant strains of various crops for the Great 

 Plains region. 



The native vegetation on different types of land in the Great 

 Plains and Great Basin regions has been studied in relation to the 

 various factors of physical environment. The results prove that the 

 composition and character of the natural growth is a reliable indi- 

 cator of the capabilities of the land for crop production, reflecting 

 with remarkable sensitiveness the average conditions with respect to 

 soil moisture and the presence or absence of injurious quantities of 

 alkali. These investigations indicate that the native vegetation can 

 be used in the rapid and accurate classification of new land as (1) 

 suitable for dry farming, (2) suitable for crop production under 

 irrigation, and (3) nonagricultural. 



PROGRESS IN COTTON WORK. 



For the past 12 years systematic work has been carried on with 

 a view to discovering fundamental principles which would aid the 

 producers of the South in the matter of securing better types, larger 

 yields, and varieties of cotton resistant to various diseases. The 

 breeding work has resulted in securing numerous varieties which 

 have taken their place among the people as standard sorts. 



The advent of the boll weevil made it necessary to give careful con- 

 sideration to the readjustment of cotton varieties throughout the 

 invaded territory. This work led to discoveries of great importance 

 m the matter of local adjustment, a hitherto neglected factor. It also 

 developed the important fact of the serious deterioration of cottons 

 by chance hybridization. 



