Asks whether vegetable mould has an acid reaction. The contents of intestines of earthworms and castings are acid, which leads him to inquire about mould.
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The Charles Darwin Collection
The Darwin Correspondence Project is publishing letters written by and to the naturalist Charles Darwin (1809–1882). Complete transcripts of letters are being made available through the Project’s website (www.darwinproject.ac.uk) after publication in the ongoing print edition of The Correspondence of Charles Darwin (Cambridge University Press 1985–). Metadata and summaries of all known letters (c. 15,000) appear in Ɛpsilon, and the full texts of available letters can also be searched, with links to the full texts.
Asks whether vegetable mould has an acid reaction. The contents of intestines of earthworms and castings are acid, which leads him to inquire about mould.
Discusses acidity of earthworm castings. JHG’s reply will make him more cautious.
Would like to see W. A. Detmer’s paper [Landwirtsch. Versuchs-Stat. 14 (1871): 248–300] and S. W. Johnson’s work [How crops feed].
Comments on food value of white and brown bread.
Returns the two books JHG had lent him. "I can plainly see I had better say nothing about the acidity of common mould."
Regrets that he has not strength enough to visit [Rothamsted].
Quantity of nitrogen in castings surprises CD.
Comments on papers: [J. B. Lawes and J. H. Gilbert, "Results of experiments on mixed herbage, pt 1", Philos. Trans. R. Soc. Lond. 171 (1880): 289–416; Gilbert, Lawes and M. T. Masters, "pt 2: The botanical results", Philos. Trans. R. Soc. Lond. 173 (1882): 1181–413].
Has never made sections to see how deep worms burrow – five or six feet is probable. Wishes the problem had arisen when he made his observations.
The laboratory has scarcely any experimental evidence on acidity of humus soil and earthworm excreta. Refers CD to some sources of information.
Sends some books.
Invites CD to visit Rothamsted. The experimental plots are at their best "as illustrating the vast influence of external conditions on the character and results of the struggle between the numerous components of an established mixed herbage".
Thanks CD for Earthworms.
Discusses the problem of accounting for difference between nitrogen in permanent grassland and ordinary arable soil. Finds castings of earthworms rich in nitrogen. Asks CD if his observations enable him to explain the source. If from below top-soil, it would be a considerable manuring.