EXPERIMENTS ON CLOVER. 145 



" Both portions of the clover-soil thus contained about the same 

 percentage of organic matter, and yielded nearly the same amount 

 of nitrogen. 



" In addition, however, to the nitrogen in the clover-roots, a 

 good deal of nitrogen, in the shape of root-fibres, decayed leaves, 

 and similar organic matters, was disseminated throughout the fine 

 soil in which it occurred, and from which it could not be sepa- 

 rated ; but unfortunately. I neglected to weigh the soil from a 

 square yard, and am, therefore, unable to state how much nitrogen 

 per acre was i^resent in the shape of small root-fibres and other 

 organic matters. 



"Before mentioning the details of the experiments made in the 

 next season, I will here give the composition of the ash of the par- 

 tially cleaned clover-roots : 



COMPOSITION OF ASH OF CLOVER-ROOTS, (PARTIALLY 

 CLEANED). 



Oxide of iron and alumina 11.73 



Lime 18.49 



Mae7iesia 3.0:^ 



Potash 6.88 



Soda 1.9:3 



Phosphoric acid 3.61 



Suli)huric acid 3.24 



Soluble silica 19.01 



Insoluble silicious matter 24.83 



Carbonic acid, chlorine, and loss 8.25 



lOO.OJJ 



"This ash was obtained from clover-roots, which yielded, when 

 perfectly dry, in round numbers, eight per cent of ash. Clover- 

 roots, washed quite clean, and separated from all soil, yield about 

 five per cent of ash ; but it is extremely difficult to clean a large 

 quantity of fibrous roots from all dirt, and the preceding analysis 

 distinctly shows, that the ash of the clover-roots, analyzed by me, 

 was mechanically mixed with a good deal of fine soil, for oxide of 

 u'on, and alumina, and insoluble silicious matter in any quantity, 

 are not normal constituents of plant-ashes. Making allowance for 

 soil contamination, the ash of clover-roots, it will be noticed, con- 

 tains much lime and potash, as well as an appreciable amount of 

 phosphoric and sulphuric acid. On the decay of the clover-roots, 

 these and other mineral fertilizing matters are left in the surface- 

 soil in a readily available condition, and in considerable propor- 

 tions, when the clover stands well. Although a crop of clover 

 removes much mineral matter from the soil, it must be borne in 

 mind, that its roots extract from the land, soluble mineral fertiliz- 



7 



