Darwin on humus and the earthworms : the formation of vegetable mould through the action of worms with observations on their habits / by Charles Darwin ; with an introduction by Sir Albert Howard.

  • Darwin, Charles, 1809-1882.
Date:
1945
Catalogue details

Licence: Public Domain Mark

Credit: Darwin on humus and the earthworms : the formation of vegetable mould through the action of worms with observations on their habits / by Charles Darwin ; with an introduction by Sir Albert Howard. Source: Wellcome Collection.

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    observed that the moles, which were abundant in the two dunged plots, always moved from one of these plots to the other in a straight line across the artificially manured plot between and never threw up any molehills on this land. They seemed to know by instinct that such areas were useless as feeding grounds. From such a simple experiment as this much could be learned. The deleterious effect of artificials on the earth¬ worm population could easily be demonstrated by a set of counts. The reaction of moles to artificials would be obvious from the absence of molehills. If the behaviour of the grazing animal is watched, it will be found that the two dunged plots will be grazed to the ground, while the artificially manured plots are only lightly picked over. When, therefore, in the cycle—humus-filled soil, the grass carpet, and the animal—a sub¬ stitute for humus is introduced in the shape of chemicals, the earth¬ worms first abandon such soil, the moles follow suit, while the grazing animal records an adverse verdict on the quality of the forage. These results have been confirmed in the United States where sulphate of ammonia is sometimes used to destroy the earthworms on golf put¬ ting greens and tennis lawns because the castings interfere with these games by clinging to the ball. In Farmers' Bulletin 1569 of the United States Department of Agriculture published in 1935 it is stated: The results of three years’ application of ammonium sulphate to sod on the experimental farm of the Department of Agriculture at Arlington, Pa., for fertilizing purposes have shown incidentally that earthworms were eliminated from the plots where this chemical was used. When applied to soils which are naturally neutral or slightly acid in character, this fertilizer creates a strongly acid condition that is distasteful to the worms and they disappear.’ The use of artificial manures is not the only modern practice which destroys the earthworm. Hardly less injurious are the poison sprays such as Bordeaux mixture and other powders containing copper salts, tar oils, and the lime sulphur washes used for the control of insect pests. Perhaps the most complete account of such results is that given by Dreidax in the Archiv fiir Pflanzenbau, 7, 1921, and in Rationelle Land- wirtschaft, Wilhelm Andermann, Berlin, 1927. The first of these papers concludes with a long list of references dealing among other matters with investigations on the earthworm since The Formation of Vegetable Mould was published in 1881. In the latter work Dreidax sums up his observations on the deleterious effects of poison sprays on the earth¬ worm population of vineyards in Germany. While examining a vineyard situated in the Markgraf near Auggen in south Baden, in which poison sprays were constantly used, he found a surprising fall from the abundant earthworm population of meadows