5. In this first season, neither the weight nor the measure of the offal corn was recorded separately; and in former papers, the bushels and pecks of total corn (including offal) have erroneously been given as dressed corn. To bring the records more in conformity with those relating to the other years, 5 per cent, by weight, has been deducted from the total corn previously stated as dressed corn, and is recorded as offal corn; this being about the probable proportion, judging from the character of the season, the bulk of the crop, and the weight per bushel of the dressed corn. Although not strictly correct, the statements of dressed corn, as amended in this somewhat arbitrary way, will approximate more nearly to the truth, and be more comparable with those relating to other seasons, than those hitherto recorded.
These were the results of the harvest of 1844. The first year of these since celebrated experiments.
If Mr. Lawes expected that the crops would be in proportion to the minerals supplied in the manure, he must have been greatly disappointed. The plot without manure of any kind, gave 15 bushels of wheat per acre; 700 lbs. of superphosphate of lime, made from burnt bones, produced only 38 lbs. or about half a bushel more grain per acre, and 4 lbs. less straw than was obtained without manure. 640 lbs. of superphosphate, and 65 lbs. of commercial sulphate of ammonia (equal to about 14 lbs. of ammonia), gave a little over 19½ bushels of dressed wheat per acre. As compared with the plot having 700 lbs. of superphosphate per acre, this 14 lbs. of available ammonia per acre, or, say 11½ lbs. nitrogen, gave an increase of 324 lbs. of grain, and 252 lbs. of straw, or a total increase of 576 lbs. of grain and straw.
On plot No. 19, 81 lbs. of sulphate ammonia, with minerals, produces 24¼ bushels per acre. This yield is clearly due to the ammonia.
The rape-cake contains about 5 per cent of nitrogen, and is also rich in minerals and carbonaceous matter. It gives an increase, but not as large in proportion to the nitrogen furnished, as the sulphate of ammonia. And the same remarks apply to the 14 tons of farm-yard manure.
We should have expected a greater increase from such a liberal dressing of barn-yard manure. I think the explanation is this: The manure had not been piled. It was probably taken out fresh from the yard (this, at any rate, was the case when I was at Rothamsted), and plowed under late in the season. And on this heavy land, manure will lie buried in the soil for months, or, if undisturbed, for years, without decomposition. In other words, while this 14 tons of barn-yard manure, contained at least 150 lbs. of nitrogen, and a large quantity of minerals and carbonaceous matter, it did not produce a bushel per acre more than a manure containing less than 12 lbs. of nitrogen. And on plot 19, a manure containing less than 15 lbs. of available nitrogen, produced nearly 4 bushels per acre more wheat than the barn-yard manure containing at least ten times as much nitrogen.
There can be but one explanation of this fact. The nitrogen in the manure lay dormant in this heavy soil. Had it been a light sandy soil, it would have decomposed more rapidly and produced a better effect.
As we have before stated, John Johnston finds, on his clay-land, a far greater effect from manure spread on the surface, where it decomposes rapidly, than when the manure is plowed under.
The Deacon was looking at the figures in the table, and not paying much attention to our talk. “What could a man be thinking about,” he said, “to burn 14 tons of good manure! It was a great waste, and I am glad the ashes did no sort of good.”
After the wheat was harvested in 1844, the land was immediately plowed, harrowed, etc.; and in a few weeks was plowed again and sown to wheat, the different plots being kept separate, as before.