. Plant physiology. Plant physiology. 66 PHYSIOLOGY OF NUTRITION lated the medium with three species of bacteria at the same time: Bacillus ramosus, Nitrosomonas and Nitrobader. If only B. ramosus and Nitrosomonas are introduced the process is limited to the formation of nitrous acid (nitrites), while B. ramosus and Niirobader produce only ammonia. Inoculation with Nitrosomonas and Nitrobader leaves the bouillon unchanged. AH these rela- tions may be shown by a diagram, reproduced below, in which the bacteria that decompose organic compounds to form ammonia are represented by a, those that for
. Plant physiology. Plant physiology. 66 PHYSIOLOGY OF NUTRITION lated the medium with three species of bacteria at the same time: Bacillus ramosus, Nitrosomonas and Nitrobader. If only B. ramosus and Nitrosomonas are introduced the process is limited to the formation of nitrous acid (nitrites), while B. ramosus and Niirobader produce only ammonia. Inoculation with Nitrosomonas and Nitrobader leaves the bouillon unchanged. AH these rela- tions may be shown by a diagram, reproduced below, in which the bacteria that decompose organic compounds to form ammonia are represented by a, those that form nitrites are represented by b, and those that oxidize nitrous to nitric acid (nitrites to nitrates) are represented by c. a + b + c a + b a + c b + c Organic Nitrogen Ammonia .Nitrogen Nitrite Nitrogen Nitrate Nitrogen No alteration of organic Pig. 42.—Comparison of the effect of nitrate and of ammoniuni salts on growth of plants in bog-soil, which is poor in lime. O, no fertilizer; NO3, nitrate added; NH3, ammonium salts added. {After P. Wagner.) Now that we have become acquainted with the process of nitrification, we may consider the question whether higher plants are able to obtain their nitro- gen only as nitrates or whether they can assimilate ammonium salts directly, without previous nitrification of the latter. Recent discoveries favor the view that nitrates act chiefly, if not exclusively, as the soiurce of nitrogen for such plants. The experiments of Wagner' have shown that nitrates and ammo- nium salts have different effects according to the nature of the soil employed. Turnips were grown in vessels of a bog-soU very poor in calcium. In one series of experiments some of the vessels contained no nitrogen fertilizer, others each contained 2 g. of nitrogen as nitrates, and still others each contained about 2 g. of nitrogen as ammonium salts. In a second series calcareous marl was added throughout, in addition to the fertilizers mentioned above. The results
Size: 2020px × 1237px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., book, bookcentury1900, bookdecade1910, booksubjectplantphysiology
