EXPERIMENTS ON CLOVEK. 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 present 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 



Magnesia 3.03 



Potash 6.88 



Soda 1.93 



Phosphoric acid 3.61 



Sulphuric acid 2.24 



Soluble silica 19.01 



Insoluble silicious matter 24.83 



Carbonic acid, chlorine, and loss 8.25 



100.00 



" 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 

 live 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 

 iron, 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 



