This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1911 edition. Excerpt: ...one must suppose that the bare arable soil would have a more powerful absorbing effect upon the air above it than the grass land. Moreover, there is Do falling off in the absorption of nitrogen above the arable land in the months of September and October, months of the year during which this field (permanent ...
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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1911 edition. Excerpt: ...one must suppose that the bare arable soil would have a more powerful absorbing effect upon the air above it than the grass land. Moreover, there is Do falling off in the absorption of nitrogen above the arable land in the months of September and October, months of the year during which this field (permanent wheat) is being cultivated, when it would expose a maximum of fresh absorbing surface. The small difference between the grass and arable land is best explained by the difference in exposure, which results in a much more vigorous air circulation above the arable field: and this conclusion is strengthened by the fact that the greater absorption above the arable land is much more marked for the upper dishes than for the lower. Table II. Total Nitrogen as Ammonia absorbed per dish in 10 months (mg.). The dishes on the laboratory lawn shew by far the highest figures, due doubtless to the greater contamination of the air by the chimneys that are near. The difference between the upper and lower dishes is also most pronounced on the laboratory lawn, which would again agree with the conclusion that the source of ammonia is aerial, i.e. that in the main it comes from the chimneys. It may be noticed that the amount of absorption by the upper dish on the laboratory lawn reached comparatively high figures on certain occasions, being over the milligramme in November 1908, October and December 1909, and January, September and October 1910. It has not been found possible to correlate these variations with the prevailing weather, but it should be noted that, with the exception of September 1910, they occur in the winter half of the year when the consumption of coal would be at a maximum. If the comparison between winter and summer months is made for all the...
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