“On plot 5, with 300 lbs. of superphosphate of lime per acre, the plants came up first, and exhibited a healthy, dark-green appearance, which they retained for some time. This result was not anticipated, though it is well known that superphosphate of lime has the effect of stimulating the germination of turnip-seed, and the early growth of the plants to an astonishing degree; yet, as it has no such effect on wheat, it appeared probable that it would not produce this effect on Indian corn, which, in chemical composition, is very similar to wheat. The result shows how uncertain are all speculations in regard to the manurial requirements of plants. This immediate effect of superphosphate of lime on corn was so marked, that the men (who were, at the time of planting, somewhat inclined to be skeptical, in regard to the value of such small doses of manure), declared that ‘superphosphate beats all creation for corn.’ The difference in favor of superphosphate, at the time of hoeing, was very perceptible, even at some distance.
“Although every precaution was taken that was deemed necessary, to prevent the manures from mixing in the hill, or from injuring the seed, yet, it was found, that those plots dressed with ashes and guano, or with ashes and sulphate of ammonia, were injured to some extent. Shortly after the corn was planted, heavy rain set in, and washed the sulphate of ammonia and guano, down into the ashes, and mutual decomposition took place, with more or less loss of ammonia. In addition to this loss of ammonia, these manures came up to the surface of the ground in the form of an excrescence, so hard that the plants could with difficulty penetrate through it.
“It will be seen, by examining the table, that although the superphosphate of lime had a good effect during the early stages of the growth of the plants, yet the increase of ears of corn in the end did not come up to these early indications. On plot 5, with 300 lbs. of superphosphate of lime per acre, the yield is precisely the same as on plot 2, with 100 lbs. of plaster (sulphate of lime), per acre. Now, superphosphate of lime is composed necessarily of soluble phosphate of lime and plaster, or sulphate of lime, formed from a combination of the sulphuric acid, employed in the manufacture of superphosphate, with the lime of the bones. In the 300 lbs. of superphosphate of lime, sown on plot 5, there would be about 100 lbs. of plaster; and as the effect of this dressing is no greater than was obtained from the 100 lbs. of plaster, sown on plot 2, it follows, that the good effect of the superphosphate of lime was due to the plaster that it contained.
“Again, on plot 4, with 150 lbs. of sulphate of ammonia per acre, we have 90 bushels of ears of sound corn, and 15 bushels of ears of soft corn, (‘nubbins,’) per acre; or a total increase over the plot without manure, of 38 bushels. Now, the sulphate of ammonia contains no phosphate of lime, and the fact that such a manure gives a considerable increase of crop, confirms the conclusion we have arrived at, from a comparison of the results on plots 2 and 5; that the increase from the superphosphate of lime, is not due to the phosphate of lime which it contains, unless we are to conclude that the sulphate of ammonia rendered the phosphate of lime in the soil more readily soluble, and thus furnished an increased quantity in an available form for assimilation by the plants—a conclusion, which the results with superphosphate alone, on plot 5, and with superphosphate and sulphate of ammonia, combined, on plot 6, do not sustain.
“On plot 12, half the quantity of sulphate of ammonia, was used as on plot 4, and the increase is a little more than half what it is where double the quantity was used. Again, on plot 13, 200 lbs. of Peruvian guano per acre, gives nearly as great an increase of sound corn, as the 150 lbs. of sulphate of ammonia. Now, 200 lbs. of Peruvian guano contains nearly as much ammonia as 150 lbs. sulphate of ammonia, and the increase in both cases is evidently due to the ammonia of these manures. The 200 lbs. of Peruvian guano, contained about 50 lbs. of phosphate of lime; but as the sulphate of ammonia, which contains no phosphate of lime, gives as great an increase as the guano, it follows, that the phosphate of lime in the guano, had little, if any effect; a result precisely similar to that obtained with superphosphate of lime.
“We may conclude, therefore, that on this soil, which has never been manured, and which has been cultivated for many years with the Ceralia—or, in other words, with crops which remove a large quantity of phosphate of lime from the soil—the phosphate of lime, relatively to the ammonia, is not deficient. If such was not the case, an application of soluble phosphate of lime would have given an increase of crop, which we have shown was not the case in any one of these experiments.
“Plot 10, with 400 lbs. of unleached wood-ashes per acre, produces the same quantity of sound corn, with an extra bushel of ‘nubbins’ per acre, as plot 1, without any manure at all; ashes, therefore, applied alone, may be said to have had no effect whatever. On plot 3, 400 lbs. of ashes, and 100 lbs. of plaster, give the same total number of bushels per acre, as plot 2, with 100 lbs. of plaster alone. Plot 8, with 400 lbs. ashes, and 150 lbs. of sulphate of ammonia, yields three bushels of sound corn, and five bushels of ‘nubbins’ per acre, less than plot 4, with 150 lbs. sulphate of ammonia alone. This result may be ascribed to the fact previously alluded to—the ashes dissipated some of the ammonia.
“Plot 11, with 100 lbs. of plaster, 400 lbs. ashes, 300 lbs. of superphosphate of lime, and 200 lbs. Peruvian guano (which contains about as much ammonia as 150 lbs. sulphate of ammonia), produced precisely the same number of total bushels per acre, as plot 4, with 150 lbs. sulphate of ammonia alone, and but 4 bushels more per acre, than plot 13, with 200 lbs. Peruvian guano alone. It is evident, from these results, that neither ashes nor phosphates had much effect on Indian corn, on this impoverished soil. Plot 14 received the largest dressing of ammonia (500 lbs. 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 lbs. of plaster, on plot 2. The 200 lbs. of Peruvian guano, on plot 13, and which cost about $6, gave an increase of 14 bushels of shelled corn, and 6 bushels of ‘nubbins.’ This will pay at the present price of corn in Rochester, although the profit is not very great. 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, but to ascertain, if possible, what constituents of manures are required, in greatest quantity, for the maximum growth of corn. **Hitherto, no experiments have been made in this country, on Indian corn, that afforded any certain information on this point. Indeed, we believe no satisfactory experiments have been made on Indian corn, in any country, that throw any definite light on this interesting and important question. A few years ago, Mr. Lawes made similar experiments to those given above, on his farm, at Rothamsted, England; but owing to the coolness of the English climate, the crop did not arrive at maturity.