Imágenes de páginas
PDF
EPUB

"As a result of these investigations the large majority of agricultural chemists and plant physiologists accepted it as an established fact that the vegetable growth of the world must depend for its nitrogen upon the amount already present in the soil, in addition to the relatively small amount absorbed by the soil as ammonia, from the atmosphere or brought down as ammonia and nitrous and nitric acids in the dew, rain and snow. It was admitted that there is a considerable difference between the food habits of cereals and of clover or legumes, but the ability of the latter to grow consecutively on the same soil for years without the aid from artificial supplies of nitrogen, and their failure in most instances to respond to the application of nitrogenous manures, was regarded as preeminently due to a difference in root habit and not to any power in the latter to assimilate free nitrogen. It was known that the insoluble nitrogenous constituents of the soil are not assimilable in any considerable measure by the cereals, but it was thought possible that the legumes, including the clovers, might be able to attack and assimilate these insoluble compounds which always form the larger proportion of the nitrogenous matter of soils. Nor was it overlooked that there are drains upon nitrogen contained in the part of the crops removed and not returned as manure to the soil. pecially prominent was the loss by the subsoil drainage, in consequence of which our rivers annually pour immense quantities of valuable constituents into the sea. Upon striking a careful balance the adherents of this school must admit that under agricultural conditions the loss is greater than the gain; or, in other words, that we are living upon the nitrogen supplied and stored up during previous ages and that this reserve is being surely and steadily exhausted wherever the most careful farming is practiced."

Es

In a recent number of Agricultural Science, Dr. Manley Miles, writes as follows:

"The researches of Schloesing and Muntz (1887-8) and the conclusive verification of their results by Warrington at Rothamstead, proving that nitrification is caused by an organized ferment, has given a new interest to the study of the nitrification of soils, and manures, as we now have a satisfactory explanation of much that had before been involved in obscurity.

"As a factor in the complex processes of plant nutrition, and in the widely discussed question as to the origin of the available supplies of nitrogen to vegetation, the microbes, which are now generally admitted to be the active agents in the process of nitrification, need to be carefully studied, their life history traced, and the conditions which have an influence on their vital activities definitely determined.

"In the widening of this prolific field of research, the chemical and physical constitution of soils can now be profitably investigated in greater detail, with the aid of all the modern improved methods which the progress of science may render available, not only with reference. to the tracing of the involved chemical reactions which are taking place, but to give the required data for making a rational estimate of the biological conditions which are essential to the well-being and vital activities of the minute organisms concerned in the metabolism of soils and manures in their relations to the nutrition of plants.

"The practical importance of the microbes of nitrification has repeatedly been recognized since the discovery of their specific role in the economy of nature, but as yet but little has been done in the investigation of their habits and life history.

[ocr errors]

"Dr. Masters has ventured the prediction that the farmer of the future may be able to apply to the soil the ferment producing germs needed to change its quality and render it available for plant food,' as the gardener sows the spawn' in his mushroom beds, or the brewer uses yeast to secure the desired process of fermentation.

66

In referring to the probable results of a knowledge of the true theory of nitrification, Prof. Storer says: Not only will farmers soon learn to make composts and to apply manure in a more rational manner than was possible before, but they will take pains to foster and protect the ferment germs and to sow them as it were, and cultivate them in fit places.'

"In my studies of the microbes of nitrification for several months past, in the intervals of other work, several points of interest have presented themselves which can only be reported in general terms as suggesting lines of further research that may be profitably followed, from the fact that the experiments are still in progress, and definite conclusions in regard to the results of modifying influences in the cultivation of the organisms cannot therefore be made.

"The method of investigation adopted is that of pure cultures in a variety of nutritive media, both liquid and solid, in test tubes plugged with sterilized cotton, and also in the case of liquid media in Steanberg's sealed culture bulbs. The microscopic study of the microbes, in the series of cultures has been checked by frequent qualitative chemical tests to determine the activity of the organisms in their specific role.

"One of the most noticeable peculiarities of the liquid cultures already made is the clearness of the culture media in which the microbes of nitrification are grown, which is in striking contrast to the opalescent or clouded cultures of B. termo, B. subtilis and other allied forms in the same media. A macroscopic examination is not therefore sufficient to determine the success or failure of an inoculation, as is the case with the latter species, and the microscope must be used to trace the progress of the development of the germs with which the liquid is seeded.

"In all of the cultures repeated tests for nitrous acid were made, but it was rarely present, and when it was detected it was in cultures which gave no nitric acid reaction and in which micrococci were found in considerable numbers, together with the peculiar microbes of nitrification, but whether the nitrous acid was produced by the micrococci (as seemed probably from their uniform presence when it was found, and their absence when it was not present), or, by a modified action of the true nitric acid microbe was not determined; and it is a question even as to whether the micrococci are a distinct species or a stage in the development of the true microbe of nitrification."

As leguminous plants are favored in their growth by the nitrates elaborated for them by microbes, so on the other hand it appears to be a legitimate inference that the microbes may in their turn be benefited by the roots of leguminous species near. which they find the most suitable conditions for their growth and development, while they are at a disadvantage in the vicinity of the roots of other plants.

In the same essay from which we have already quoted, Prof. Frear writes as follows:

"There has been some discussion upon the character of the organisms producing this fermentation, and some have urged that the oxi

dizing effect may be due to a number of similar species, but the majority attribute it to the action of a single special ferment, which has been isolated. This ferment placed in appropriate liquids, increased at first slowly, and afterwards rapidly. Upon sowing the proper nutritive solutions with ordinary soil there is first obtained a transformation of the nitrogenous matter into ammonia, unless the nitrogen is already present in that form. Ladureau is inclined to attribute their transformation to the action of the special ferment. After the formation of ammonia has begun, nitrates are formed as the first oxidation products, possibly, as Warrington is inclined to believe, through the activity of another special ferment, and finally the nitric fermentation proper sets in. Schlossing and Muntz found that exposure to a temperaure of 212° F. for ten minutes killed the organism, and that 195° was highly detrimental; on the other hand, its activity was slight below fifty-four degrees, and most vigorous at about eighty degrees. That, therefore, nitrification practically ceases during winter. Dessication of a soil almost entirely stopped the action of the ferment. Free access of oxygen was essential for its oxidizing action; when it is shut off from the soil the process going on in the latter is greatly changed in character. As would be readily imagined from this circumstance, the depth from which a soil sample is taken, exerts an important influence on the activity of the ferment contained. Warrington stated recently that the ferment is always found at the depth of two feet, but less frequently, and in much less vigorous condition, until a depth of six feet was reached. The subsoil nitrogen proved to be readily nitrifiable when freely exposed to the air."

Forests and Rainfall.

After the organization of the State Board of Agriculture, in 1877, the question of forestry and the effect of forests upon rainfall was one of the first to receive the attention of its Secretary, and in its report for that year will be found fifty pages of printed matter and diagrams, giving all that could then be urged upon the question involved. Since then the Board of Agriculture, by its standing committee on Forests and Forestry, and by the annual report of its Secretary, has nearly every year called the attention of farmers and the Legislature to the importance of the subject. These reports embrace all that can be given as reliable, and, while they discard much that is mere theory, carry with them the main points of interest to the student of climatology.

The examinations of subsequent years add very little to our stock of knowledge upon the topic, and the subject when reviewed goes back extensively to the same authorities then cited, and to the same points then argued. All recent data, from whatever source obtained, merely confirms what we have urged in these annual and quarterly reports.

At different times since our report of 1877, drafts of proposed laws, intended to affect and promote the interest of forestry, have been introduced into the legislature; some of these were of such a nature as not to receive legislative endorsement, and others became laws after various modifications. Those which were enacted are either inoperative or thus far without advantageous effect, and the result of ten years of legislation only increases the belief which we expressed ten years ago, viz: That a law or plan which fails to show a pecuniary

profit to the owners of forest and rough land, will eventually fail to affect its desired purpose. We may prove beyond all doubt that an increase of our forest area is for the benefit of the State and the nation, but until we can prove that re-forestration of large areas of rough or mountain land is to the individual interest of the land owner, we will fail to accomplish the desired result. If we can once convince the owners of this class of land, much of which has already been denuded of its timber, that the second growth, if allowed to grow, will give them a good interest upon the investment, we will have accomplished much more than ever can be done by legislation; so long as we fail to show that such investments are or will be profitable, we may offer bounties and exempt timber lands from taxation in vain; if it will not pay as an investment, the exemption from the small amount of tax will not make it profitable; if it will not pay to recover these old timber areas with trees of natural growth, the fact that we may present the owner with suitable trees will not induce them to plant and care for them. There must be a fair margin for a profit above interest upon capital, or the attempt will end in failure.

We then must squarely meet the question of "Will it pay?" for after all that is and will be the test of the enterprise. Many who are in a position to be thoroughly acquainted with the facts of the case assert that it will pay; among these we know of no better authority than Thomas Meehan, the Botanist of our Board, who writes as follows:

"Long ago, I showed that we could expect little from individual effort. We may show a young man of thirty that a plantation of twenty-five or thirty acres would be immensely profitable when he reached sixty. It would be a nice laying up of money for old age; or a capital life insurance for his family, in case of an earlier death. But few men care to deliberately lock up ground for a century or half a century. In a new country like ours, changing conditions make it probable that, before that time, land may be worth much more than the forest, long before the forest has reached market value. The minds of few men are proof against these considerations.

"The remedy is in coöperative associations. A stock company should. be formed, large enough to secure tracts of sufficient size to employ a force to look after the trees properly. The stock would always be worth more than its added interest, because the trees are nearing their market value. If one wanted money before the trees were mature, the stock would find a ready market. Of course there would be details in the carrying out of such a project that would require good judgment. The land to be secured might be in locations that would be improving, so that after the century of timber, there would be money in the ground also. This would give value to the stock as time rolled along. The trees best adapted to the location would also require good judgment, and there are many other similar matters of detail, but which an expert in forestry management could work out for such a company."

Assuming the correctness (without admitting it) of the argument that the expense of planting the young trees and keeping the weeds down for several years, will so increase the cost of the investment as to make it unprofitable, we still have the plan of re-forestration by allowing the natural growth to recover the ground. In the advocacy of this plan, we are invariably met with the statement that a forest fire will in a few hour destroy the growth and labor of several years,

and that the forest fires are chargeable with the destruction of a very large proportion of the young timber which is annually allowed to start after the removal of the older growth. A little practical examination will clearly prove that this young growth is burned over and destroyed, not from any inherent weakness of its own, but simply because the limbs, brush and all the debris of the former crop of timber is left on the ground to carry the fire over the tract and to increase its heat to a point which will destroy the young growth. Where all of this debris has been taken off or carefully burned off, we have no trouble from forest fires. The young growth will not, of itself, furnish enough of leaves and twigs to support the flame, or if it does, the heat will not be sufficient to kill the young trees. This we think will eventually prove to be the true solution of the much-vexed timber question, and which will, if anything does, lead to the replenishing of forests in our State. Arbor Day will, of course, have its effect, but that can only be shown to a very limited extent, and will always be more as an element of beauty than as an adjunct to our timber supply or a regulator of climate and rainfall.

If we are correct in this reasoning, it then remains to see how far we can, by legislative enactment, encourage the owners of the proper kinds of land, to permit them to grow up with natural timber. Attempts in this direction have thus far been confined to three modes: First, by encouraging the planting of trees along our public roads by exempting the owner from a certain portion of taxes; second, by offering those willing to test the matter, trees grown at the expense of the State, free of charge, and third, exemption of the land planted or allowed to grow up with natural growth from all or a portion of the taxes now levied upon it. Of these the first is practically inoperative and for the good of public travel it is best that it should be so. The second did not meet with legislative approbation, and the third is yet untried, with a grave doubt as to the constitutionality of the plan. None of these plans have yet met with any practical response from the land owner whose interest they were intended to affect; hence they may, except the last, be considered as inoperative and ineffective, and we are compelled to adopt some other plan. This will be the duty of the commission which the Governor has been authorized to appoint, and the result of their labor will be looked for with great interest by those who have made this branch of political economy a partial study.

To the theory of the effect of forests upon rainfall and climate, we have very little to add to what was written ten years ago; we then wrote as follows(annual report of 1877, page 63):

"Passing to the consideration of the effect of forests upon streams, and, by reverse reasoning, to the effect of the destruction of our fores's upon streams, we naturally consult the authorities of older countries, and also of the older classes of our citizens. No one will deny that our rivers and larger streams, where the result is most readily noted, are lower in summer and higher in winter than formerly, or that they are more liable to disastrous and sudden freshets than they were fifty years ago; the rafting season on the Susquehanna and its tributaries is shorter and less reliable than formerly, and for this reason our annual supply of lumber is irregular and precarious. The fact being admitted, and we do not think it will be denied, we next look for a cause, and naturally infer that it is due to some irregularity in the source of supply. If, as the Governor has claimed, and as is

« AnteriorContinuar »