BUREAU OF SOILS. 493 



priation be made to enable the bureau to give advice upon this 

 specific point. 



As already stated, one of the three principal methods of soil 

 control is crop rotation, the other two being fertilization and tillage. 

 The principles of crop rotation and its eifect upon the soil have 

 never been worked out. It is believed that with the present ad- 

 vance of knowledge and the information and methods at the dis- 

 posal of the bureau it is in a position to determine this principle, and 

 an appropriation is needed for this very important and funda- 

 mental work. It is altogether probable that it will be found that 

 the rotations adapted to one type of soil will not be necessarily 

 most effective on other soil types. These are problems that vitally 

 concern the farmer. Their solution may save years required to work 

 the problem out by field methods. Not only does it require a long 

 time to determine such matters in the field, but at the end of 15 or 

 25 years or more needed to get the information the soil itself may 

 have changed materially from what it was at the beginning. 



The bureau is constantly in receipt of requests for the investiga- 

 tion of adverse soil conditions affecting special crops, such as citrus 

 fruits, apples, peaches, and potatoes, or of problems connected with 

 the management of lawns and parks, clover-sick soils, and the 

 like, which it has been impossible to investigate with the funds at our 

 disposal. An appropriation should be made for this work in order 

 that a special effort may be given to the solution of some of these 

 practical problems affecting the farmer or city dweller, problems 

 Avhich can not be adequately handled in the course of the investiga- 

 tions being made in the laboratories at the present time. 



DIVISION OF SOIL WATER AND EROSION. 



Ever since the Bureau of Soils was established the study of soil 

 moisture has been recognized as a difficult yet fundamentally impor- 

 tant line of work. The part of this work dealing with the move- 

 ment of moisture in the soil has been carried forward in the physi- 

 cal laboratory. The part involving field investigations as to the 

 depth beneath the surface of the ground water, as to the changes in 

 depth attending settlement and cultivation, as to the general move- 

 ment of the ground waters, and as to the surface run-off of rains and 

 the removal of the soil through erosion has been given attention for 

 the past four years, and the results have been found to throw light on 

 some of the most important problems of our agriculture. Two note- 

 worthy publications on the subject have been issued within the year, 

 and two others are well advanced in preparation. It is believed that 

 the extension of the investigations and tlie utilization of the mate- 

 rial already in the bureau are of such importance as to warrant an 

 approj^riation of $10,000 for this work. 



LINES OF WORK FOR WHICH SPECIFIC APPROPRIATIONS AR:3 



DESIRED. 



Division of Soil Surveys : 



*Eeconnoissance surveys. 



*Detailed surveys of counties in cooperating States. 



*Detailed surveys of counties in noncooperating States. 



Detailed surveys of experiment station farms. 



Detailed surveys of forest reserves. 



State soil maps. 



