150 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



LIFE HISTORIES OF INSECTS. 



During the 16 years the complete life histories of many hundreds 

 of species of injurious insects have been worked out, and the publi- 

 cations of the service during that period cover in competent form 

 practically all of the principal crop pests of the United States. 



SOIL INVESTIGATIONS. 

 FEARS OF SOIL EXHAUSTION. 



For the fiscal year 1897 there was appropriated for the Division of 

 Soils $15,300, while for the year 1912 the appropriation for the 

 Bureau of Soils was $262,060. In the former period the work was 

 3 years old, and the foundation for subsequent development was still 

 being laid. 



For 60 years the scientists of the world had wrestled with Liebig's 

 mineral theory of plant food without progressing much beyond the 

 limits of his classical work. No practical or efficient basis of classifi- 

 cation of soils had been worked out, the adaptation of crops to soils 

 was not api^reciated, there was no rational theory of fertilization, no 

 specific knowledge of how fertilizers act upon the soil or plant, and 

 no efficient methods of determining the manurial requirements of a 

 soil. 



Moreover, our people have always been an adventurous people ; the 

 country sparsely settled and new in experience and tradition. 

 Methods of culture and crop rotation adapted to the different soils 

 were little understood or considered of minor importance. The im- 

 pression was general that the soils of the country were wearing out 

 with ever-decreasing productivity, and alarm was felt for the future 

 of our increasing population and the possibility of the ultimate 

 exhaustion of our soils and of the natural deposits of fertilizer ma- 

 terials, which it was claimed were essential for the maintenance of 

 the proper mineral composition of agricultural lands. 



These are subjects that are at the very foundation of the Nation's 

 prosperity, and are matters that I have had deeply at heart during 

 my term of service. 



THE SOIL AN INDESTRUCTIBLE ASSET. 



As a result of the profound investigation in the Bureau of Soils 

 of reported cases of soil exhaustion, it appears that all such cases 

 are due principally to mismanagement of tillage operations, to the 

 lack of proper adaptation of soils and crops, to the unwise rotation 

 of crops, and to the misuse of fertilizers and manures, making it a 

 personal failure rather than a natural and fundamental deterioration 

 of the soil. It can be said, therefore, that the soil is the one inde- 



