1. Top-dressed in the Spring.
This year, the seed and manures were sown in the autumn. And I want the Deacon to look at plot 0. 3 cwt. of Peruvian guano here gives an increase of 10½ bushels of wheat, and 1,948 lbs. of straw per acre. This will pay well, even on the wheat alone. But in addition to this, we may expect, in our ordinary rotation of crops, a far better crop of clover where the guano was used.
In regard to some of the results this year, Messrs. Lawes and Gilbert have the following concise and interesting remarks:
“At this third experimental harvest, we have on the continuously unmanured plot, namely, No. 3, not quite 18 bushels of dressed corn, as the normal produce of the season; and by its side we have on plot 10b—comprising one-half of the plot 10 of the previous years, and so highly manured by ammoniacal salts in 1845, but now unmanured—rather more than 17½ bushels. The near approach, again, to identity of result from the two unmanured plots, at once gives confidence in the accuracy of the experiments, and shows us how effectually the preceding crop had, in a practical point of view, reduced the plots, previously so differently circumstanced both as to manure and produce, to something like an uniform standard as regards their grain-producing qualities.
“Plot 2 has, as before, 14 tons of farm-yard manure, and the produce is 27¼ bushels, or between 9 and 10 bushels more than without manure of any kind.
“On plot 10a, which in the previous year gave by ammoniacal salts alone, a produce equal to that of the farm-yard manure, we have again a similar result: for two cwts. of sulphate of ammonia has now given 1,850 lbs. of total corn, instead of 1,826 lbs., which is the produce on plot 2. The straw of the latter, is, however, slightly heavier than that by the ammoniacal salt.
“Again, plot 5a, which was in the previous season unmanured, was now subdivided: on one-half of it (namely, 5a1) we have the ashes of wheat-straw alone, by which there is an increase of rather more than one bushel per acre of dressed corn; on the other half (or 5a2) we have, besides the straw-ashes, two cwts. of sulphate of ammonia put on as a top-dressing: two cwts. of sulphate of ammonia have, in this case, only increased the produce beyond that of 5a1 by 7⅞ bushels of corn and 768 lbs. of straw, instead of by 9¾ bushels of corn and 789 lbs. of straw, which was the increase obtained by the same amount of ammoniacal salt on 10a, as compared with 10b.
“It will be observed, however, that in the former case the ammoniacal salts were top-dressed, but in the latter they were drilled at the time of sowing the seed; and it will be remembered that in 1845 the result was better as to corn on plot 9, where the salts were sown earlier, than on plot 10, where the top-dressing extended far into the spring. We have had several direct instances of this kind in our experience, and we would give it as a suggestion, in most cases applicable, that manures for wheat, and especially ammoniacal ones, should be applied before or at the time the seed is sown; for, although the apparent luxuriance of the crop is greater, and the produce of straw really heavier, by spring rather than autumn sowings of Peruvian guano and other ammoniacal manures, yet we believe that that of the corn will not be increased in an equivalent degree. Indeed, the success of the crop undoubtedly depends very materially on the progress of the underground growth during the winter months; and this again, other things being equal, upon the quantity of available nitrogenous constituents within the soil, without a liberal provision of which, the range of the fibrous feeders of the plant will not be such, as to take up the minerals which the soil is competent to supply, and in such quantity as will be required during the after progress of the plant for its healthy and favorable growth.”
These remarks are very suggestive and deserve special attention.
“The next result to be noticed,” continue Messrs. Lawes and Gilbert, “is that obtained on plot 6, now also divided into two equal portions designated respectively 6a and 6b. Plot No. 6 had for the crop of 1844, superphosphate of lime and the phosphate of magnesia manure, and for that of 1845, superphosphate of lime, rape-cake, and ammoniacal salts. For this, the third season, it was devoted to the trial of the wheat-manure manufactured under the sanction of Professor Liebig, and patented in this country.