. Bacteria in relation to soil fertility. Soil microbiology; Bacteriology, Agricultural. NON-SYMBIOTIC NITROGEN FIXATION 141. that the maximum fixation was attained where no combined nitro- gen was purposely added and that on the addition of such^ fixa- tion of nitrogen was diminished. Following Winogradski, Caron made some very interesting discoveries. He found that soils under leafy crops contain greater numbers of bacteria than those under grasses. He also observed that the bacterial flora of soils in ' the spring is different from that in the fall both quantitatively and qualitatively. He
. Bacteria in relation to soil fertility. Soil microbiology; Bacteriology, Agricultural. NON-SYMBIOTIC NITROGEN FIXATION 141. that the maximum fixation was attained where no combined nitro- gen was purposely added and that on the addition of such^ fixa- tion of nitrogen was diminished. Following Winogradski, Caron made some very interesting discoveries. He found that soils under leafy crops contain greater numbers of bacteria than those under grasses. He also observed that the bacterial flora of soils in ' the spring is different from that in the fall both quantitatively and qualitatively. He used in vege- tation experiments pure cultures of the bacteria most frequently encountered in natural soils. Some soils were inoculated with bouillon culture, whereas others received only sterile bouillon. The crop yields were usually in favor of the inoculated plots but showed varia- tions from season to seasoju- Ex- ceptionally good results were ob- tained with a spore-bearing bacillus which he termed Bacillus ellenbachensis, Caron's work led to the commercial exploitation of his cul- tures, one of which, *'alinit," was the subject of much study and discussion. This culture was found to contain, according to Severin, two closely related bacilli which he chose to designate as B, ellenbachensis A. and B. These had the power to fix nitro- gen to some extent. Tests with "alinit," however, have not con- firmed to any great extent the claim of its exploiters. In 1901 Beijernick's investigation led to the extremely im- portant discovery of aerobic bacilli to which he gave the name Axotobacter. Since that time many species of non-symbiotic nitrogen-fixing organisms have been found and much learned concerning their life activities, until today we recognize that the power of fixing nitrogen is inherent in many bacteria, yeasts, Fig. 30.—Clostridium pasteurlan- ium (after Winogradski).. Please note that these images are extracted from scanned page images that may have b
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectbacteriologyagricult
