6o8 



Journal of Agricultural Research voi. xiii, no. 12 



Table III. — Comparison of the composition of peat and saw grass 



Silica 



Iron oxid and alumina . 



Lime 



Magnesia 



Soda 



Potash 



Phosphoric acid 



Nitrogen 



Percent- 

 age loss. 



20. o 



29-3 



41-3 

 82.6 



5 

 7 

 29-4 



97- 

 68. 



The losses obtained for the two samples of surface peat cited agree 

 very well except in the case of the iron oxid and alumina, and even here 

 the variation is not excessive. No comparison was made with the subsoil 

 peats because they have been subjected to the leaching action of water 

 so long that more or less of all the elements present must have been 

 removed. In the subsoil la there appears to have been a considerable 

 loss of silica, while both samples contain much less nitrogen than those 

 taken from nearer the surface. However, this is to be expected when it 

 is considered that hundreds, if not thousands, of years have elapsed since 

 the deposition of these lower strata. 



The comparatively small loss of lime suffered by the saw grass may 

 seem surprising at first, and it is unusual, as this constituent is leached 

 very readily from ordinary soils. There are two possible explanations 

 for its behavior under the circumstances. In the first place, the lime is 

 present in the plant for the most part as difficultly soluble compounds 

 (calcium oxalate, etc.), and in the second place, owing to the great 

 abundance of calcium carbonate in the Everglades, the solvent action of 

 the waters upon the lime in the peat must be far less than it would be 

 under other conditions. 



In the formation of ordinary soils, potash is held by adsorption, and, 

 hence, suffers a lower percentage loss than some of the less soluble ele- 

 ments; but this constituent is leached very readily from leaves and 

 vegetation,^ and nearly the entire amount originally present in the 

 saw grass has been removed in the transformation to peat. 



The enormous accumulation of nitrogen in the peat is an interesting 

 phase of the change undergone by the saw grass. The loss of nitrogen 

 seems to be very gradual, and even in the subsoil there is still a very 

 high percentage of this element. The prevailing poor conditions for 

 bacterial activity while the peat is being formed both preclude the possi- 

 bility of nitrogen fixation, and also account for the greater stability of 

 the nitrogen in the peat than in ordinary soils, wherein the nitrogen is 

 oxidized to nitrate and thus leached. 



^ LE Clerc, J. A., and Brezeale, J. F. plant Food removed from growing pi,ants by rain or 

 DEW. In U. S. Dept. Agr. Yearbook, 1908, p. 389^402. 1909. 



