Identifier: agriculturalinve22gilb (find matches)
Title: Agricultural investigations at Rothamsted, England, during a period of fifty years. Six lectures delivered under the provisions of the Lawes Agricultural Trust
Year: 1895 (1890s)
Authors: Gilbert, Joseph Henry, 1817-1901 Lawes Agricultural Trust Association of American Agricultural Colleges and Experiment Stations
Subjects: Agriculture, Experimentation.
Publisher: Washington, Govt. Print. Off.
Contributing Library: U.S. Department of Agriculture, National Agricultural Library
Digitizing Sponsor: U.S. Department of Agriculture, National Agricultural Library

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Fig. 1.—Peas grovni in experiments on the fixation of free nitrogen. First, as to the peas. There was limited growth in pot 1, with sandwithout soil extract, and there was an entire absence of nodule forma-tion on the roots. The increased growth in pots 2 and 3, with soilextract, was coincident with a very great development of nodules. In pot 4, with garden soil itself supplying abundance of combinednitrogen and doubtless microorganisms as well, there was also a con-siderable development of nodules, but distinctly less than in either pot2 or pot 3 with sand and soil extract only. Lastly, without soil extract FIXATION OF FREE NITROGEN. 127 and without nodules there was no gain of nitrogen, but with soil extractand with nodule formation there was much gain of nitrogen, therebeing many times as much in the products of growth as in the seedsown. For illustration of the above-ground growth see fig. 1, p. 12G.
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Fig. 2.—Vetches grown in experiments on the fixation of free nitrogen. With the vetches, as with the peas, there was very restricted above-ground growth without soil extract seeding (So. 9), and this wasassociated with very limited root development, and with the entireabsence of nodule formation. On the other hand, the greatly extendedvegetative growth with soil extract (Nos. 10 and 11), was associated 128 AGRICULTURAL INVESTIGATIONS AT KOTHAMSTED. with an immense development of root and root fiber, and with the for-mation of numerous nodules. Again, in the garden soil (Xo. 12), withits liberal sutpply of combined nitrogen as well as microorganisms,there was much less development of roots and less also of nodules thanin the pots with sand and soil extract only. Further, without microbeseeding and with no nodules there was no gain of nitrogen, while withmicrobe seeding and with numerous nodules there was considerablegain of nitrogen, there being, with much less nitrogen in the seed a

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