152 TALKS OX MANURES. 



bushel, and o,000 lbs. of straw, removes Irom the laud on which it 

 isgrown, 30 lbs. of phos|)horic aeiil. The clover-soil analyzed by 

 me, eousequeutly coutaius aii amount of phosphoric acid in a 

 depth of ouly six inches, which is equal to that present in 247A 

 average crops of wheat; or supposing that, by good cultivation 

 and iu favoral)le seasons, tiie average yield of wheat could be 

 doubled, and 5U bushels of grain, at Hi) lbs. a bushel, and G,000 lbs. 

 of straw could be raised, 124 of such heavy wheat-crops would con- 

 tain no more phosphoric acid than actually occurred in six inches 

 of this clover-soil per acre. 



" The mere presence of such an amount of jdiosphoric acid in a 

 soil, however, by no means proves its sufliciency for tlie produc- 

 tion of so many crops of wheat ; for, in the first place, it can not 

 be shown that the whole of the i)hosphoric acid found by analysis, 

 occurs in the soil in a readily available combination ; and, in the 

 second place, it is quite certain that the root fibres of the wlicat- 

 plant can not reach and p\ck up, so to speak, every particle of 

 phosphoric acid, even suppc^sing it to occur in the soil in a form 

 most conducive to ' ready assimilation by the plant.' 



"Tiie calculation is not givi-n in proof of a conclusion which 

 would be manifestly absurd, but simply as an illustration of the 

 enormous quantity in an acre of soil six inches deep, of a constitu- 

 ent forming the smaller proportions of the whole weight of an 

 acre of soil of that limited depth. It shows the existence of a prac- 

 tically unlimited amount of the most important mineral constitu- 

 ents of jilants, and dearly points out the pro]iriety of rendering 

 availaitle to plants, the natural resources of the soil in plant- 

 food ; to draw, in fact, up the mineral wealth of the soil, by thor- 

 oughly working the land, and not leaving it unutilized as so much 

 dead capital." 



" Good," said tlie Deacon, " that is the right doctrine." 



" The roots," continues Dr. Yoelcker, " from one square foot of 

 soil were cleaned as much as possible, dried completely at 212% 

 and in that state weighed 240 grains. An acre consequently con- 

 tained l,493i lbs. of dried clover- roots. 



"The clover-roots contained, dried at 212' Fahr., 



Organic matter* ^V^ 



Mineral matter,t (ash) 1^67 



100.00 



* Yielding nitrogen 1.6r5 



Equal to ammonia ^-^l^' 



flncluding iusoluble silicious matter, (clay and sand) 11.67 



