CONVENTION OF OFFTCrAL AORTOULTUEAL CHEMISTS. 433 



oHicial nu'thod were not very concordant. It was suggested that possil)ly better 

 results iniglit be obtained with a temi)eratnre somewhat lower than 130° C. The 

 referee recommended that the association take some action as to the determination 

 of moisture in potash salts l)y drying at a stated temperature or by ignition, and that 

 the method thought most desirable be studied further, with a ^'iew to securing more 

 concordant results. 



SOILS. 



The work on this subject under the direction of the referee related 

 to the determination of available potash and phosphoric acid in soils, 

 methods for the analysis of alkali soils, and a study of soil acidity. 

 The association approved the referee's reconunendation that tests be 



N • 



made of greater concentrations than .^^ hydrochloric acid for deter- 

 mining available phosphoric acid. The suggestions for further work 

 on the solubilit}" of phosphoric acid and potash in the different soil 

 layers, an investigation of methods for determining total phosphoric 

 acid, and the proposed method for the determination of water-soluble 

 constituents in alkali soils were left to the discretion of the next 

 referee. 



Several changes in the official methods for the analysis of soils pro- 

 posed by the referee were approved. These are two evaporations and 

 liltrations for the removal of silica from acid solutions, the introduc- 

 tion of the volumetric method for phosphoric acid as an alternate 

 method, and the requirement that in the determination of humus the 

 filtered ammonia extract be clear and free from turbidit3^ The referee 

 for next year was requested to test the value of proposed methods for 

 comparing the ability of different soils to support the growth of nitri- 

 f^dng organisms under different conditions. The matter of testing the 

 methods for determining water-soluble plant food in soils described in 

 Bulletin 22 of the Bureau of Soils was brought up and referred to the 

 next referee. 



A report of investigations relating to the fixation of atmospheric 

 nitrogen was presented by J. G. Lipman, and remarks concerning the 

 use of Redonda phosphate on acid soils were made b}^ H. J. Wheeler. 



Report of referee, F. P. Vkitcii. — In a number of soils examined by the referee and 



N 

 C. C. Moore, jiotash and phosphoric acid were determined in extracts made with oTjk 



hydrochloric acid, and potash was also determined in aqueoiis extracts. The results 

 indicated that the acid extraction usually removed less phosphoric acid and more 

 potash than were removed by the crops grown. The referee therefore recommended 

 that tests be made of stronger acid solutions in the determination of phosphoric acid. 

 The results with water as a solvent for potash were not considered as bearing out the 

 indications of preliminary work, but were believed to be of sufficient significance to 

 justify further tests with the ratio of solvent to soil changed from 5 to 1 to 10 to 1. 

 Methods for determining total [)hosphoric acid were also believed to need further 

 investigation. The methods for alkali soils were tested l)y A. Seidell and B. E. Brown, 

 attention being ])aid to tlie ratio of soil to water and the effect of time on the solu- 



