Agricultural investigations at Rothamsted, England, during a period of fifty yearsSix lectures delivered under the provisions of the Lawes Agricultural Trust . In sand. Sopt. 24. In soil, Sept. 26. In sand. Nov. 20. In soil, Dec. 2. Fh;. 4.—Peas grown in experiments on the fixation of free nitrogen. 1890. watered with the extract from a rich soil; also in a mixture of twoparts rich garden soil and one part of sand. The pits, with theirplants, were exposed to the open air, bnt protected from heavy rain. 138 AGRICULTURAL INVESTIGATIONS AT ROTHAMSTED. In the sand the infection was comparatively l
Agricultural investigations at Rothamsted, England, during a period of fifty yearsSix lectures delivered under the provisions of the Lawes Agricultural Trust . In sand. Sopt. 24. In soil, Sept. 26. In sand. Nov. 20. In soil, Dec. 2. Fh;. 4.—Peas grown in experiments on the fixation of free nitrogen. 1890. watered with the extract from a rich soil; also in a mixture of twoparts rich garden soil and one part of sand. The pits, with theirplants, were exposed to the open air, bnt protected from heavy rain. 138 AGRICULTURAL INVESTIGATIONS AT ROTHAMSTED. In the sand the infection was comparatively local and limited, butsome of the nodules developed to a great size on the roots of the weakplants so grown. In the rich soil the infection was much more generalover the whole area of the roots, the nodules were much more num-erous, but generally very much smaller. Eventually the nodules were. In sand, June 12. 1831. In soil, June In sruid, Sept. 11,1801. In soil, Sept, 14,1891. Fig. 5.—Sainfoin grown in experiments on the fixation of tree nitrogen. picked off the roots, counted, weighed, and the dry substance and thenitrogen in them determined. Among the annuals the peas, and among the plants of longer lifethe sainfoin, showed perhaps the most normal growth: and figs. 4 and5 and the results given in Table 4G (p. 139) afford interesting illustra-tions. FIXATION OF FREE NITROGEN. 139 : in.—Experiments at Bothamsted on the fixation of free nitrogen—Plants grown inpits and taken up at successive 2)criods, 1S90-01 (l,in sand (with ash), microbe seeded;:. in a mixture of rich soil and sand). Dote oftaking up. Nmnherof plant!! Nodules. Approx-imatenumber. Weight,dried at100° C. Nitrogen. In dry. Actual. PEAS. 1S90. In sand: First period Second period Third period In soil: First period Second period Third period Aug. 4,1800Sept, 120,18C0 Aug. 5,1
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