6o6 



Journal of Agricultural Research 



Vol. XIII. No. 12 



The determination of silica was made according to the method of the 

 Association of Official Agricultural Chemists/ the figure stated thug 

 representing silica of constitution only. Phosphoric acid and the alka- 

 lis were determined in the usual manner, and the remaining constituents 

 by the modified Glaser method described by Mellor.^ The significance 

 of separate values for iron and aluminium oxids was not deemed of 

 importance, and therefore they are reported together. A test was made 

 for titanium, but it was not found in any part of the saw-grass plant. 

 The results of the analyses are given in Table I. 



Table I. — Composition of saw grass 



Constituent. 



Percentage of dry material. 



Leaves. 



Root 

 crowns. 



Average. 



Silica (SiOj) 



Ironoxid (FegOg) and alumina (AI2O3) 



Lime (CaO) 



Magnesia (MgO) 



SodaCNajO) 



Potash (K2O) 



Phosphoric acid (P2O5) 



Nitrogen 



o. 10 

 . 16 



•52 

 . 10 



• 14 

 •35 

 •OS 

 .62 



It will be noted that there is comparatively little variation in the com- 

 position of the three parts of the plant, with the possible exception of the 

 silica content, and therefore the average of the values found for the three 

 parts is taken as the composition of the saw grass for the subsequent 

 comparisons. The values given are very near the true ones, even in the 

 case of the silica, since it is probable that leaves and roots contribute in 

 nearly equal amounts in the formation of peat. 



DESCRIPTION AND COMPOSITION OF PEAT 



The peat deposit in the Everglades resulting from the accumulation of 

 the remains of saw grass and varying in depth to about 10 feet, covers a 

 vast area. Near the surface the peat is brown in color, has a loose, 

 fibrous structure, and is very light when dry. It has an ash content of 

 from 7 to 10 per cent. At depths below the surface the material becomes 

 darker in color and less fibrous in texture as the depth increases, grading 

 finally into a black, plastic, compact mass almost free from plant fiber. 

 The ash content also increases slightly with the depth, but even at depths 

 of 6 or 7 feet no free mineral matter can be detected, except in limited 



' Wiley, H. W., ed. OFFiaAi, and provisional methods of analysis, assoqation of OFFiaAL 



AGRICULTURAL CHEMISTS, AS COMPILED BY THE COMMITTEE ON REVISION OF METHODS. U. S. Dept. Agr. 



Bur. Chem. Bui. 107, p. 22. 1907. 



^Mellor.J.W. a TREATISE ON QUANTITATIVE inorganic ANALYSIS, p. 60&-609. London, Philadelphia, 

 1913- 



