[2868] See B. xii. c. [52], as to this notion.
[2869] The reason being, that in such cases the soil is saturated with thyme, origanum, mint, and other odoriferous herbs.
[2870] This opinion is contrary to that expressed by Columella, B. ii. c. 1; but the justice of it is universally recognized. Upon this theory, too, is based the modern practice of alternating the crops in successive years, the necessity of providing for heavy rents, not allowing the land to enjoy absolute rest.
[2871] This has not come to pass even yet, nearly two thousand years since the days of Pliny.
[2872] See B. v. c. 3, and B. xviii. c. 21.
[2873] Fée taxes our author here with exaggeration. For Byzacium, see B. v. c. 3, and B. xviii. c. 21.
[2874] Nevertheless, as Fée remarks, the method is often practised with great success. Pliny is at issue here with Theophrastus, De Causis, B. iii. c. 25.
[2875] A natural mixture of argilla and calcareous stones, or subcarbonate of chalk. Fée remarks, that the ancients were not acquainted with the proper method of applying it. Marl only exercises its fertilizing influence after being reduced to dust by the action of the atmosphere, by absorbing the oxygen of the air, and giving to vegetation the carbonic acid that is necessary for their nourishment.
[2876] “White argilla.” This, Fée thinks, is the calcareous marl, three varieties of which are known, the compact, the schistoid, and the friable.
[2877] At the present day there are only two varieties of marl recognized, the argillaceous and the calcareous; it is to the latter, Fée thinks, that the varieties here mentioned as anciently recognized, belonged.