The Origin and Nature of Soils (Paperback)

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. 1892 Excerpt: ...this store of nutriment may be sought by the roots of the trees which grow in the superincumbent soil. It is, however, only where the birds resort to some districts for breeding purposes that they considerably influence the character of the soil. When, a few decades ago, the passenger pigeons existed in the Mississippi Valley in very great numbers, they had the habit of nesting in a gregarious manner, millions of them occupying the same tract of wood. This area of timber they possessed for 2 or 3 months while they reared their young. Feeding through the forests over a wide range of country, and often extending their search for food for 20 or more miles in every direction from their roost, these swift winged creatures, able to fly at a speed of 60 or 80 miles an hour, supplied their young with food conveyed in their crop and spent the night at the nesting place. The quantity of the excrement voided by these birds on the ground beneath the trees in which they nested was very great; at the end of the season it often formed a layer of guano-like material over a district perhaps a thousand or more acres in extent. The result of this action was after a few years to provide the under earth with an important store of plant food; at times the quantity of this material was so great as to destroy the lesser vegetation by the manurial salts which, although of utmost value to plants, can not be tolerated by them in excessive quantity. Where these birds resort in great numbers to a shore for breeding they are sure to contribute a large amount of plant food to the soil. If the rookery be thinly occupied, as is generally the case with the eider duck and some other water fowl, the sufficient but not excessive manuring may produce a rank vegetation which shows that the soil ...