Ivi INTRODUCTION. 



alone. It is evident, from these results, that neither ashes nor phosphates had much effect on Indian 

 corn ou this impoverished soil. 



Plot 14 received the largest dressing of ammonia, (500 pounds of Peruvian guano,) and produced 

 much the largest crop, though the increase is not so great in proportion to the guano as where smaller 

 quantities were used. 



The manure which produced the most profitable result was the 100 pounds of plaster on plot 2. 

 The 200 pounds of Peruvian guano on plot 13, and which cost about $6, gave an increase of fourteen 

 bushels of shelled corn and six bushels of &quot;nubbins.&quot; The superphosphate of lime, although a very 

 superior article, and estimated at cost price, in no case paid for itself. The same is true of the ashes. 



But the object of the experiment was not so much to ascertain what manures will pay, as to as 

 certain, if possible, what constituents of manures are required in greatest quantity for the maximum 

 production of corn. All our agricultural plants are composed of the same elements; the only difference 

 being in the relative proportions in which they exist in the plants. Thus, wheat and turnips contain 

 precisely the same elements, but the ash of wheat contains five times as much phosphoric acid as the 

 ash of turnips ; while the turnips contain much more potash than wheat. This fact being ascertained 

 by chemical analysis, it was supposed that wheat required a manure relatively richer in phosphoric acid 

 than was required for turnips. This is certainly a plausible deduction; but careful and numerous ex 

 periments have incontrovertibly proved that such is not the case ; in fact, that an ordinary crop of 

 turnips requires more phosphoric acid, in an available condition in the soil, than an ordinary crop of 

 wheat. From this fact, and several ethers of a similar character, the conclusion is irresistible, that the 

 chemical composition of a plant the relative proportion in which the several elements exist in the 

 plant is not a certain indication of the manurial requirements of the plant; or, in other words, it does 

 not follow that because a plant contains a relatively larger proportion of any particular element, that 

 the soil or manure best adapted for the growth of this plant must contain a relatively larger proportion 

 of this element. 



Wheat, rye, barley, oats, and Indian corn all contain a relatively large quantity of phosphate of 

 lime; but it is not safe to conclude from this, that a soil or manure best adapted for their maximum 

 growth must also contain a relatively large quantity of phosphate of lime. It is known positively, from 

 numerous experiments, that such is not the case with wheat; and it is, therefore, at least doubtful 

 whether such is true of Indian corn. On the other hand, we know, from repeated experiments, that 

 wheat requires a large quantity of ammonia for its maximum growth; and as Indian corn is nearly 

 identical in composition to wheat, it is somewhat probable that it requires food similar in composition. 

 This, however, is merely a deduction never a safe rule in agriculture. We cannot obtain positive 

 knowledge in regard to the requirements of plants, except from actual experiments. Numerous ex 

 periments have been made in this country with guano and superphosphate of lime ; but the superphos 

 phates used were commercial articles, containing more or less ammonia ; and if they are of any benefit 

 to those crops to which they are applied, it is a matter of uncertainty whether the beneficial effect of 

 the application is due to the soluble phosphate of lime or to the ammonia. On the other hand, guano 

 contains both ammonia and phosphate, and we are equally at a loss to determine whether the effect is 

 attributable to the ammonia or phosphate, or both. In order, therefore, to determine satisfactorily 

 which of the several ingredients of plants is required in greatest proportion for the maximum growth of 

 any particular crop, we must apply the ingredients separately, or in such definite compound s as will 

 enable us to determine to what particular element or compounds the beneficial effect is to be ascribed. 

 It was for this reason that sulphate of ammonia and a purely mineral superphosphate of lime were used 

 in the above experiments. No one would think of using sulphate of ammonia at its present price as 

 an ordinary manure, for the reason that the same quantity of ammonia can be obtained in other sub 

 stances, such as barn-yard manure, Peruvian guano, &c.. at a much cheaper rate. But these manures 

 contain ALL the elements of plants, and we cannot know whether the effect produced by them is due 

 to the ammonia, phosphates, or any other ingredient. For the purpose of experiment, therefore, we 



