Fertilizing Lawn and Garden Soils

To make a good lawn or, a productive garden, the soil must be reasonably fertile or be made so by special treatment. and It must be kept fertile by the regular use .of manure or other suitable fertlllzers

Bacteriological studies of field soils, III. The effects of barnyard manure

The conclusions which may be drawn from the experiments upon the effects of barnyard manure on bacteriological activities of field S\u27oils presented in this bulletin are as follows: 1. Applications of manure up to sixteen tons per acre increased the numbers of organisms in the soil as shown by the growth on modified synthetic and albumen agar. The ammonifying power of the soil as shown by tests with the casein-fresh soil, albumen-fresh soil, dried blood-fresh soil, and dried blood-air-dried soil methods, and the nitrifying power tested by the ammonium sulfate-fresh soil, and the ammonium sulfate-air- dried soil methods were likewise increased. 2. The greatest increases occurred between the check soil and that receiving eight tons per acre and between the soil receiving the eight tons and that to which twelve tons per acre were applied. In most cases only a very slight increase occurred in the soil on which sixteen tons were used over that where twelve tons were added. 3. Twenty tons of manure per acre caused a depression in numbers of bacteria, in ammonifying power, and in nitrifying power according to all the methods employed, the results being lower than those secured when twelve tons per acre were added. 4. Albumen agar permitted of the development of larger numbers of soil organisms than the modified synthetic agar and also permitted of a greater differentiation between the soils of the various plots. 5. There was a close relationship between the ammonifying power of the soils and the numbers of organisms in them accord-to the methods used in this work. 6. The casein-fresh soil method of testing the ammonifying power of the soil was the simplest, permitted of the greatest differentiation between different soils, and in general was the most satisfactory. 7. The ammonium sulfate-fresh soil method for testing the nitrifying power of the soil showed the greatest differences between the·various soils ,and is recommended as the more rational method. 8. The nitrifying power and the ammonifying power of the soil according to the method\u27s used proceeded in the same direction. 9. Applications of manure up to sixteen tons per acre increased the yield of corn from the plots in this series, the greatest increases occurring between the check plot and that receiving eight tons per acre, and between the latter and the plot to which twelve tons per acre were added. A very slight further increase occurred when sixteen tons per acre were applied. 10. Twenty tons of manure per \u27acre depressed the crop yield below that obtained when twelve tons per acre were added. 11. The results of the bacteriological tests and the crop yields coincide almost exactly. Further evidence is thus supplied that there is a close relationship between bacterial activities and the fertility or crop-producing power of soils. 12. The depression in crop yields \u27and bacterial activities caused by twenty tons of manure per acre cannot be attributed to denitrification as tests by the Giltay solution method and the soil method give no evidence of losses of nitrogen. The depression must therefore be due to physiological or other causes

Bacteria at different depths in some typical Iowa soils

1. In the different soil types, as well as in the same soil under different rotations, the greatest number of organisms occurred at a depth of 4 inches. 2. Bacteria were found in considerable numbers at much lower depths in the loess soil than in the drift soil. 3. There was a more or less gradual decrease in numbers to a depth of 3, 5 and in one case of fifteen feet. No sudden increases were observed even where gains in moisture occurred. 4. The greatest decrease in numbers of organisms occurred within the first 12 inches and in some cases within the first 8 inches. 5. The rotation of crops increased the number of organisms beyond continuous cropping. 6. At 4 inches from the surface, the soil under the three year rotation showed larger numbers than that under any two year rotation, but at 8 inches fewer organisms than the soils under the two year rotation with clover or cowpeas turned under. 7. Rye turned under in the two-year rotation decreased the number of bacteria. 8. Fewer bacteria occurred in the soil under continuous clover than in that under continuous corn, due to the difference in treatment for the crop. Little differences were shown below 12 inches depth. 9. The soil under the four year rotation showed smaller numbers than in any of the plots except those under continuous clover and corn and the two-year rotation with rye turned under, due probably largely to the crop grown. 10. The humus content of the soils in all the plots, except two, and the nitrogen content of all the soils, decreased more or less regularly down to three feet. In the plots under the two-year rotation with clover or cowpeas turned under, there was more humus at eight than at four inches from the surface. 11. While in some cases there seemed to be some relation between numbers and the humus or nitrogen content of the soils, in general the variations observed in these latter were insufficient to account for the differences in numbers. The variations in moisture content of the soils were also insufficient to account for the results. 12. Aeration may be the governing factor, or possibly the effect of toxic substances produced in the growth of plants may be the cause of the variations in the bacterial content of the different plots

The fertility in Iowa soils

Iowa soils are not inexhaustible. A survey of the state recently completed by the Iowa Agricultural Experiment station and reported in this bulletin shows clearly that it is time now for Iowa farmers to give their best thought and effort to maintaining the fertility of their farms. Hundreds of soil samples collected from the typical soil areas of the state and thoroughly analyzed show that sooner or later the production of maximum crops will he limited by the lack of some plant food element unless farming systems are changed to meet the situation. The phosphorus content of Iowa soils is not large and this element must be supplied to all the soil areas sooner or later. There is a marked tendency in many sections for Iowa soils to become acid and that must he corrected by lime applications. Even the supply of nitrogen and organic matter has its limitations also and demands more attention than commonly supposed

Some bacteriological effects of liming

These experiments were undertaken to determine the effects of liming on certain groups of soil bacteria in a typical Wisconsin drift soil. They justified the following general conclusions: 1. Applications of lime up to three tons per acre lead to an increase in the numbers of bacteria developing on modified synthetic agar. They also produce an increase in ammonification, nitrification, and in nitrogen fixation when these processes are tested by the beaker method. These increases are in all cases almost proportionate to the amount of lime applied. 2. Natural increases in numbers of bacteria tend to obscure the effects of applications of lime, while natural decreases make them more pronounced. 3. Peptone solutions do not permit of the determining of the largest number of bacteria which will destroy humus with the production of ammonia. 4. The beaker method, with dried blood or cottonseed meal for ammonification, with ammonium sulfate or dried blood for nitrification, and with mannite for nitrogen fixation, is eminently satisfactory. 5. The ammonification of dried blood or of cottonseed meal runs parallel with the numbers of bacteria while there is very little relation between the ammonification of peptone solutions and numbers. 6. Increased nitrification leads to slight accumulations of nitrates in the soil. 7. Natural accumulations of nitrates in the soil tend to obscure the differences due to the lime treatment. 8. The solution method for nitrogen fixation is quite unreliable. 9. Applications of lime increase the yield of oats; one-half and one ton per acre very slightly, but two and three tons to quite a large extent. 10. Applications of lime up to three tons per acre increase the nitrogen content of the oats crop more rapidly than the yield itself

Methods for the bacteriological examination of soils

Because the idea of examining soils bacteriologically owed its inception to the development of the gelatine plate method for isolating pure cultures, very naturally the first investigations of soil bacteria were by the use of plate cultures. the studies, therefore, were purely quantitative in nature. The results secured by the pioneers in this work demonstrated some facts of considerable interest, but it soon became evident that mere quantitative determinations of the bacteria in soils were inadequate to give information regarding the relation of such organisms and their activities to the fertility of the soil

Bacterial activities and crop production

Until the present time studies in soil bacteriology have dealt almost exclusively with the occurrence and activities of microorganisms in the soil and no attempt has been made to interpret experimental results from the standpoint of crop production. This is due, of course, to the fact that as a science soil bacteriology is scarcely out of its infancy and the preliminary investigations in any science must of necessity deal mainly with underlying principles and such studies are always apt to be rather fragmentary in character

Bacteriological studies of field soils, II. The effects of continuous cropping and various rotations

From a bacteriological study of soil plots under both continuous cropping and various crop rotations, these general conclusions were drawn: 1. The rotation of crops caused the development of greater numbers of organisms in the soil and of greater ammonifying, nitrifying, and nitrogen-fixing power by the soil, than continuous cropping either to corn or to clover. 2. Greater numbers of organisms, greater ammonifying, nitrifying, and nitrogen-fixing powers were found in a soil under a three year rotation of corn, oats, and clover, than in a soil under a two year rotation of corn and oats, or in a soil under a two-year rotation with clover, cowpeas or oats, turn en unner as green manure. 3. The use of a green manure in a two-year rotation did not always increase the number of bacteria or the ammonifying, nitrifying, or nitrogen-fixing power of the soil, and it is suggested that the explanation may be sought in the moisture factor or it may be found in the introduction of such large amounts of organic matter. 4. There was an indication that the crop present on the soil was of more importance from the bacterial standpoint than the previous cropping of the soil. 5. The ammonification of dried blood and of cottonseed meal did not always run parallel. 6. The nitrification of dried blood and of ammonium sulfate proceeded almost parallel. 7. Nitrification and ammonification proceeded in the same direction. 8. Evidence is supplied that bacterial activities and crop production are very closely related

Synthesis of α-hydroxy-β,β-difluoro-γ-ketoesters via [3,3]sigmatropic rearrangements

Readily available γ,γ-difluorinated allylic alcohols obtained from trifluoroethanol were esterified efficiently. Exposure to strong base (LDA) afforded the ester enolates, in which chelation both controlled configuration and stabilised against fragmentation, which were trapped as their silyl ketene acetals. Rearrangement occurred to afford base-sensitive acid products. Esterification under mild conditions afforded the purifiable methyl esters in which the masked ketone had been released. Educts with either a benzyloxy or an allyloxy group at the α-position could be deprotected releasing the alcohols

Bacterial activities in frozen soils

1. By means of the modified synthetic agar plate method bacteria are shown to be present in large numbers in a typical Wisconsin drift soil when it is completely frozen and the temperature is below zero degrees Centigrade; furthermore, increases and decreases in numbers of organisms occur during this period and large numbers are found after the soil has been frozen for a considerable period than before it begins to freeze. 2. During the fall season, the number of bacteria present in the soil diminishes gradually with the lowering of the temperature. 3. Frozen soils possess a much greater ammonifying power than non-frozen soils whether they are tested by the peptone solution method or by the dried blood or cottonseed meal method. 4. During the fall season, the ammonifying power of the soil increases until the temperature of the soil almost reaches zero, when a decrease occurs, and this is followed by a gradual increase and the ammonifying power of the soil reaches a maximum at the end of the frozen period. 5. The nitrifying power of frozen soils is weak and shows no tendency to increase with extension of the frozen period. 6. Frozen soils possess a decided denitrifying power which seems to diminish with the continuance of the frozen period. 7. During the fall season, the denitrifying power of the soil increases until the soil freezes, after which a decrease occurs. 8. Frozen soils possess a nitrogen-fixing power which increases with the continuance of the frozen period, being independent of moderate changes in the moisture conditions but restricted by large decreases in moisture. 9. In the fall, the nitrogen-fixing power of the soil increases until the soil becomes frozen, when it almost ceases, after which a smaller nitrogen-fixing power is established. 10. These results confirm Conn\u27s conclusion that bacteria are alive and multiply in frozen soils. The results of the physiological determinations lend support to his theory of the existence of specific groups of bacteria in the winter which are adapted to growth at low temperatures. 11. The theory is advanced that because of the surface tension exerted by the soil particles on the films of water, the presence of salts in this water, and the concentration in salts which may occur in it when the main body of soil water begins to freeze, it seems justifiable to assume that under average winter conditions, when the soil temperature is not depressed far below zero, the hygroscopic water in soils remains uncongealed and consequently bacteria may live in it and multiply sometimes to a comparatively large extent