144 DEPAETMENTAL KEPORTS. 



association. Many new methods of analysis of this class of compounds 

 were devised and tested and samples for analysis sent to 14 different 

 chemists for purposes of comparison. 



SOIL LABORATORY. 



Since the chemistry of the soil is the foundation of agricultural 

 chemistry, a special laboratory, with Mr. C. C. Moore as chief, has 

 been established to study the chemical composition of the soil and 

 the best methods of analysis. 



This laboratory has continued in a line of soil investigations which 

 were commenced in the Division of Chemistry about seven years ago. 

 Its specific work has been to devise methods whereby the amount of 

 mineral matter in a soil in a condition to be assimilated by plants 

 may be estimated, the purpose being to forecast and supply those 

 ingredients which would have been found deficient by the growing 

 plant. After a verj' elabornte series of pot experiments upon the 

 growth of oats, beans, and buckwheat, a scheme for the determina- 

 tion of the amounts of j)hosphorus pentoxide and potash available for 

 the lilant was devised. 



In the early part of the year a unification of the laboratory studies 

 was undertaken by a direct application to the actual conditions of 

 field crops. Accordingly, a series of plot experiments was begun in 

 Tennessee upon the growth of oats. Tennessee was selected for these 

 experiments because of the many varieties of soil and geological 

 formations found in that State. About 25 plots were grown, ranging 

 the full length of the State. Samples of the soil and subsoil were 

 taken at the time of seeding. These samples were analj^zed, and from 

 the results a conclusion was drawn as to the amount of phosphorus 

 and potash which would probably be utilized by the plants in the 

 course of their growth. At the maturity of the crop a sample of soil 

 was secured from an accuratel}^ defined area. From the analysis of 

 this sample the amount of mineral matter removed was calculated, and 

 the results were compared with the forecast as made from the previous 

 analysis of the soil. Very significant results were obtained, and owing 

 to the vast importance of such an investigation it was decided to 

 extend the scope of the work and verify the results by an extensive 

 application of the theory throughout the United States. 



Accordingly, a cooperative plan of study was arranged. A circular 

 outlining the nature of the work was prepared and sent to the vari- 

 ous agricultural experiment stations. Twenty-eight stations agreed 

 to undertake the work. The plan, in brief, is as follows: Each sta- 

 tion selected a typical soil, preferably one that had received no fer- 

 tilizer, which was considered the best suited for the purpose. Four 

 adjoining plots cf cereals were sown — spring wheat, oats, rye, and 

 barley. From the center of the plots and over an area of about 4 

 square feet samples of soil were secured to three successive depths of 

 9 inches. The soils and subsoils were shipped to this laboratory, 

 where a portion was used for the exiDcrimental culture in pots and the 

 remainder redistributed among the cooperating stations for analysis 

 and study. 



At maturity the crops are to be harvested and forwarded to this 

 laborator)^ where they will be analyzed and the amount of mineral 

 matter removed will be calculated. 



This is probably the most extensive chemical investigation of methods 

 to determine the fertility of soil which has been undertaken. Each 



