tion from the cottonseed meal may not increase with the numbers, at first. At subsequent dates, however, after the lime has increased not only the numbers but possibly also the vigor of the bacteria, the depressing action of the carbohydrate may be overcome and the ammonia production run parallel with the numbers. CHANGES ILLUSTRATED BY CURVES Turning now to the curves which have been plotted to show the changes in ammonifying power occasioned by the applications of lime, some interesting facts become apparent. Plate II brings out very clearly the fact previously mentioned that the differences in ammonifying power of the soils as shown by the peptone solution method, subsequent 100 2 TONS 3 TONS 1/2 TON to the first sampling, are very slight. Furthermore, there is evidently little or no relation between the total numbers of bacteria and those which ammonify peptone for enormous increases in numbers of organisms are coincident with extremely small increases in ammonia production in the peptone solutions. Turning next to Plates III and IV for the curves showing the ammonification of dried blood and cottonseed meal, we find that while some variations occur the agreement is exceptionally good. At the first and second samplings the ammonification of the dried blood was influenced to a greater degree by the applications of lime than was that of the cottonseed meal, but at the last two samplings the curves for ammonia production from dried blood and cottonseed meal are practically coincident. There also seems to be quite a definite relation between the total numbers of organisms appearing on the "modified synthetic" agar plates and the ammonification of dried blood or cottonseed meal. Large increases in total numbers NITROGEN MILLIGRAMS of organisms occur simultaneously with large gains in ammonia production. Furthermore, there is an increase in numbers of bacteria from the first to the second samplings, then a decrease at the third, and a further decrease at the fourth sampling. There is an increase in ammonia production from dried blood from the first to the second samplings, and then a decrease to the third and a slight decrease to the fourth sampling. The ammonia production from the cottonseed meal decreases steadily from the first to the fourth sampling, corresponding thus with the decrease in numbers at the third and fourth samplings, but differing at the first and second dates. In general, then, from a study of these results we may conclude that the ammonia production from dried blood is very closely related to the numbers of bacteria which develop on "modified synthetic" agar and that the ammonia production from cottonseed meal is generally analogous, but may occasionally prove otherwise. GENERAL CONCLUSIONS OF AMMONIFICATION EXPERIMENTS The conclusions to be drawn from these ammonification experiments are: 1. Applications of lime increase the ammonifying power of the soil whether tested in peptone solutions or in beakers with dried blood or cottonseed meal. 2. When dried blood or cottonseed meal is employed, the increase due to lime is almost proportional to the size of the application. 3. Peptone solutions do not permit of the development of the largest number of soil bacteria which can produce ammonia. 4. There is little or no relation between the ammonia production in peptone solutions and the numbers of bacteria in the soils. 5. The ammonia production from dried blood is quite closely related to the total numbers of organisms which appear on "modified synthetic" agar. 6. The ammonia production from cottonseed meal proceeds in the same direction with numbers of bacteria, but is not always so closely related as is that from dried blood. VII. THE NITRIFICATION EXPERIMENTS The nitrification experiments were carried out by the beaker method only, previous experiments having shown the inadequacy of the solution method, due in large measure to the losses of ammonia occurring during the necessarily long continuance of the experiment. Tables XI, XII, XIII and XIV show in detail the results obtained at the four samplings, giving also the various treatments. The figures in the last column of each table are obtained by subtracting the nitrates formed in the blank |