. Bacteria in relation to soil fertility. Soil microbiology; Bacteriology, Agricultural. THE CARBON AND NITROGEN CYCLES loi Ammonta Nifrit An/ma/s. es N/ira'te^ remain constant. But it is not—there are many leaks in the cycle. Some of the plants and animals may be burned with the liberation of free nitrogen. Millions of pounds of it reach sew- ers, and from here rivers, lakes, and oceans. In time this is broken down and the nitrates so formed are reduced by denitri- fying bacteria with the liberation of gaseous nitro- gen. The pro- cesses of decay continually going on may also liber- ate free
. Bacteria in relation to soil fertility. Soil microbiology; Bacteriology, Agricultural. THE CARBON AND NITROGEN CYCLES loi Ammonta Nifrit An/ma/s. es N/ira'te^ remain constant. But it is not—there are many leaks in the cycle. Some of the plants and animals may be burned with the liberation of free nitrogen. Millions of pounds of it reach sew- ers, and from here rivers, lakes, and oceans. In time this is broken down and the nitrates so formed are reduced by denitri- fying bacteria with the liberation of gaseous nitro- gen. The pro- cesses of decay continually going on may also liber- ate free nitrogen. Furthermore, mil- lions of pounds of nitrogen are re- turned to the air by explosives. In some of the battles of the World War enough nitrogen was liberated to produce the food of the civilized world for a year. Hence the combined nitrogen would continue to grow smaller were it not that other factors are at work in nature causing them to combine. Every flash of lightning causes some nitrogen to combine as oxides, but the quantity of combined nitrogen thus produced is relatively insig- nificant. The major factors are biological. There are within the soil two great groups of bacteria which possess the power of fixing nitrogen. The first—^the non-symbiotic nitrogen-fixing organisms living free in the soil—^are able, with the energy they obtain from the oxidation of organic carbon, to build up complex organic nitrogen compounds. There are two groups of these organisms—the aerobic and the anaerobic, the first being the more important. The other class of nitrogen fixers is the symbiotic. These live in conjunction with legumes and obtain from them carbonaceous material, and in return give combined nitrogen. In Ph/fi- Profein Fig. 25.—Illustrating nitrog-en cycle in Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly re
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Keywords: ., bookcentury1900, bookdecade1920, booksubjectbacteriologyagricult
