298 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



soy beans witli respect to the factors influencing oil production, and 

 this year peanuts and flax have been included in these experiments. 

 In carrying out the field experiments the use of plats in a series, with 

 a conijirehensive system of checks, is supplemented with tests in large 

 pots set in the field, the aim being to combine the desirable features 

 of greenhouse pot cultures with those of field-plat tests. 



Functions of the secondary elements of plant food. — A large 

 number of carefully controlled field plats are being used this year in 

 tests with several crops as to the value of the secondary elements con- 

 tained in mineral-fertilizer salts in favorably affecting crop growth. 

 Kecent investigations in this field have emphasized the possible prac- 

 tical importance of the subject. 



One of the principal problems in connection Avith these investiga- 

 tions is the development of satisfactory methods for properly con- 

 trolling the various factors of environment affecting plant growth, 

 for without such methods little can be accomplished in differentiating 

 between these several factors and heredity in crop plants. Large 

 cylinders of earthenware so placed and managed as to permit the 

 growing of plants under normal field conditions give promise of prov- 

 ing very useful in this work. 



DRY-LAND AGr.ICULTURAL INVESTIGATIONS. 



The investigations in dry-land agriculture in the Great Plains area 

 under the direction of Mr. E. C. Chilcott have progressed along the 

 lines set forth in previous reports. As a result of a material increase 

 in the appropriation for this work for the current fiscal year three 

 new stations are being established. One of these is located near Ard- 

 more, in Fall River County, S. Dak.; one near Tucumcari, N. Mex. ; 

 and the third in the southern part of the " Panhandle " of Texas. 

 The crop season has been a very trying one throughout the Great 

 Plains region. Except at the extreme northern and southern ends of 

 this region, the season has been exceptionally dry, and at several of 

 the stations no crops were harvested. Such seasons as this fully 

 demonstrate the importance of this line of investigations, and the 

 need of a considerable number of these stations at different points in 

 the area has been shown this year, when, notwithstanding crop fail- 

 ures at some of the stations, results of great value have been obtained 

 from the experiments at others. 



The results of the investigations in crop rotation and tillage 

 methods have been published during the past year. The interest ii. 

 this work is shown by the fact that the first edition of 10,000 copies 

 of the bulletin was quickly exhausted and it has been necessary to 

 issue two subsequent editions to meet the demand for information. 



Cooperative relations with the State experiment stations of the 

 different States in which the work is conducted have continued on a 

 satisfactory basis. 



WESTERN AGRICULTURAL EXTENSION. 



The Office of Western Agricultural Extension, under the direction 

 of Mr. Carl S. Scofield, has continued during the past year to op- 

 erate a number of field stations for the Bureau of Plant Industry at 

 various points in the Western States. With the exception of the 



