494 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



Division of Soil Chemistry and Physics: 

 Chemical Laboratory — 



*The routine mineral and chemical analyses of soils, waters, 

 fertilizers, and other related soil material. 



*Research in\esti<^ations of the mineral and chemical com- 

 position of soils as related to the management of soils and 

 to crop adaptation and production. 



Alkali investigations, including particularly methods of 

 reclamation and amelioration of resulting adverse physical 

 soil conditions. 



Investigation of the changes which occur in the chemical 

 and physical properties of irrigated lands. 

 Physical laboratory — 



*Research investigations in soil physics, including particu- 

 larly aeration, heat, and moisture relations. 



Soil management, including particularly methods of con- 

 trolling the physical condition of the soil through culti- 

 vation. 



*The routine mechanical analysis of soils, fertilizers, and 

 other related soil material. 

 Fertilizer laboratorj'^ — 



*Investigation of natural and artificial sources of supply of 

 fertilizer material. 



Investigation of methods of handling and manufacturing 

 fertilizer material and farm manures to realize the greatest 

 possible benefit to farmers. 



Investigation of the relative efficiency of the different forms 

 of fertilizer material. 

 Division of Soil Fertility : 



*Eesearch investigations of the maintenance of soil fertility, 

 the cause of unproductive soils, the organic origin of 

 unproductivity and effects of green manuring, the means 

 for improvement of unproductive soils, the effect of fer- 

 tilizers on soils, and field investigation of soil-fertility 

 problems in cooperjition with experiment stations. 



Soil biology — fungi, bacteria, protozoa, enzymes, and effect 

 on production of beneficial or harmful organic compounds 

 in soils. 



Inert organic matter in soils. 



Manurial requirements of extensive soil types in cooperation 

 with experiment stations. 



Manurial requirements of samples sent in by farmers. 



Principles of crop rotation and effect on soils. 



Adverse soil conditions affecting special crops, such as citrus 

 fruits, apples, peaches, potatoes, lawn and park soils, clover 

 sick soils, etc. 

 Division of Soil Water and Erosion. 



* Entries marked with an asterisk denote lines of work at present carried on by the 

 bureau. 



