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BRIEF SUMMARY OF CONCLUSIONS.

Some of the principal points that have been brought out in this collection of data will seem like the expression of ideas that have long been known, yet whose importance has probably been underrated by those who desired to deduce definite numerical relations between the climate and the crops of any locality.

(1) We have seen that in a general way the plant, like every other living being, adapts itself, when possible, to its climatic surroundings, and therefore will produce some crop, if possible, the first year and will do better and better in the next few succeeding years if the

seasons are not too severe.

So sensitive is the plant to a change of environment that the ordinary seasonal irregularities from year to year have a strong influence upon it, so that the general disposition acquired by the seed in a single dry or wet, or cold, or early, or late season prepares it for a corresponding dry or wet, cold, early, or late season next year. Or, again, a "sport" that has unexpectedly developed under the special influence of a given season and soil, and has acquired to a high degree characteristics which make it harmonize with that season, becomes the progenitor of some important variety whose adoption may, in a few years, revolutionize the agriculture of that region. The weather of any growing season affects the crops of future years by modifying the seeds of the current crop. The current season and the resulting seeds must harmonize together.

(2) If, instead of adapting the plant to the climate, we, for instance, plant the seeds proper for a moist climate in an arid region, and if we must therefore artificially irrigate in order to secure a crop, such irrigation should be looked upon, not as establishing an expensive custom to be adhered to in future ages, but as simply a temporary device to be managed in the interests of the evolution of new varieties that can eventually be cultivated in that soil and climate without irrigation. This is the result that nature has herself frequently achieved by the slow process of carrying seeds, step by step, from moist to arid regions, and which man endeavors to hasten when he carries seeds by railroad and steamship from England to our arid region.

(3) Inasmuch as the cultivation of the cereals cotton, tobacco, sugar, and other important crops will hardly be attempted except in regions where the climate is known to be reasonably in harmony with the seed that is planted, therefore we may assume that an average crop is certain under the average climatic conditions. The departure of any special season as to climate will produce a corresponding departure as to crop, but the latter must be expressed as a percentage of the average ordinary crop, and not simply in absolute measure,

as bushels or pounds, since the absolute crop depends so much upon the soil, the manuring, the cultivation, the thickness of seeding, and other details. On the other hand, the crop of one season must have some relation to the crop of the preceding season by reason of the inherited tendencies of the seed from which it was raised. The clirainfall or useful moisture rainfall or nutriment temperature or heat sunshine

and

matic factors are, as shown by Linsser, the data that must be compared with the resulting harvests.

(4) It is evident that the question of the effect of climate on a given crop in the past is not so important as the prediction of what crop will be harvested from a given field already planted. On this point I have given all the illustrations that I could find, especially in Chapter XII, showing how from an analysis of a sample at any given date one should be able to predict the resulting crop. The result can be made correct to within 10 per cent, if we allow for the ordinary average irregularities of the climate, a statement of whose extent can easily be made up from meteorological records. As to extraordinary irregularities of climate which can not be foreseen, I remark:

(a) First of all the effects of excessive droughts at each stage of the plant can be estimated from the experimental data given in Part I, and will be found to harmonize as well as could be expected with the results of actual experience as given in Part II:

(b) The effect of severe unusual droughts, or heat, or cold, or moisture are ordinarily felt over relatively small portions of the country, so that the average result is small in comparison with the whole crop available in the country; for instance, in 1890, in Kansas and Nebraska the corn harvest was one-half of its usual amount and almost the same in 1887, reckoning, of course, the yield per acre, but this and the corresponding small yields in a few other States represent only an inappreciable percentage of loss to the country at large.

(5) The studies of the effect of climate on the daily development of sugar in beets, sugar cane, or sorghum, or on the nutritious harvest of grass and cereals has shown the approximate best dates for harvesting these crops.

(6) The studies of the physiological importance of the leaves of beets will eventually show whether these should be trimmed or how they should be treated in order to stimulate the production of sugar. As the pruning of hop vines and grapevines stimulates the ripening and increases the amount of the crops, and as the plucking of the tassels from the maize apparently increases that crop, and as the plucking of the flowers and balls from the potato vines increases the growth of the tubers, so doubtless in many other ways the methods of

cultivation may be made to simulate the effects of a favorable climate, so that in general we are justified in the conclusion that while uncultivated plants and their fruits are wholly dependent on the weather, yet methods will be found by which we may render the harvests from cultivated plants largely independent of the weather.

(7) The data here collected demonstrate that the richness of the soil determines the amount of the annual cereal crop more than does the climate. The latter determines principally the dates of sowing, ripening, and the immunity from early or late frosts or the possibility of bringing the plant to maturity.

(8) We see that rain or irrigation water, so necessary as the medium for bringing the nitrogenous molecules from the soil up into the seed cells of the plant, also by drainage and seepage carries away any such molecules if these are present as earths or manures, whereas if these are present in living microbic or rotting leguminous cells they are far more available for plant use. The best method by which the nitrogen of the free air is thus made available for agriculture is elaborated in chapters VIII and IX.

(9) From the data now at hand I should say that the yield per acre for any one of the ten principal crops whose statistics are here given has probably never been either increased or diminished by 50 per cent of the normal yield per acre by climatic influences alone over any large region, such as 100 square miles, and, further, that the total annual harvest for any given crop in the United States is not likely to be diminished 5 per cent by the occurrence of an inclement season in some one portion of the country.

The detailed comparison of the climate for each season with the crop for that season has become practicable to me only since completing the table of statistics in this chapter, and it is as yet too soon to anticipate all the results that will follow therefrom.

NOTE. As these statistical tables are very voluminous and only extend to the year 1890 their publication has been deferred until they can be brought up to date. They will probably form a continuation of this present text.-C. A.

PART IV.

Chapter XIV.

CATALOGUE OF PERIODICALS AND AUTHORS REFERRED TO IN THIS REPORT BY MERELY QUOTING THE AUTHORS' NAMES AND THE DATE OF PUBLICATION.

ABBOTT, HELEN C. DE S. Plant analysis as an applied science. Journal of the Franklin Institute, 1887. Vol. CXXIV, pp. 1–33.

The chemical basis of plant forms. Journal of the Franklin Institute, 1887. Vol. CXXIV, pp. 161–185.

AGRICULTURAL EXPERIMENT STATION, Amherst, Mass. Eighth Annual Report of the Board of Control. Boston, 1890.

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AGRICULTURAL SCIENCE. A monthly periodical. Charles S. Plumb, ed.

Vol. I,

Geneva, N. Y., 1887; Vol. II, Knoxville, 1888; Vol. III, Knoxville, 1889; Vol. IV, Knoxville, 1890; Vol. V, Lafayette, Ind., 1891.

ANDRÉ, CH. Influence de l'altitude sur la température. Lyon, 1886? ANGOT, ALFRED. Étude sur la marche des phénomènes de la végétation en France pendant les années 1880 et 1881. Annales du Bur. Cent. Mét. de France, année 1882, Tome I. Paris, 1884.

Étude sur la marche des phénomènes de la végétation et la migration des oiseaux en France pendant les années 1882 et 1883. Cent. Mét. de France, année 1884, Tome I. Paris, 1886.

Annales du Bur.

Annales du Bur.

Étude sur la marche des phénomènes de la végétation et la migration des oiseaux en France pendant les années 1884 et 1885. Cent. Mét. de France, année 1886, Tome I. Paris, 1888. Étude sur la marche des phénomènes

de la végétation et la migration Annales du Bur.

des oiseaux en France pendant les années 1886 et 1887. Cent. Mét. de France, année 1888, Tome I. Paris, 1890. ANONYMOUS. Climate of Massachusetts. The Gardeners' Chronicle. London, - 1842.

ASSMANN, R. Ueber die Mitwirkung von Rauhreif und Glatteis bei der Abtragung von Gesteinmassen in den Gebirgen. Naturw. Rundschau, 1887, Nr. 47, S. 421-423. Wollny, X, p. 388.

ATWATER, W. O. Experiment Station Record, Department of Agriculture. Vol. I, 1889, and Vol. II, 1891.

AUGUSTIN, F. Ueber die jährliche Periode der Richtung des Windes. Separatabdruck a. d. Sitzungsber. d. k. Böhm. Ges. d. Wissensch., Prag, 1886. Zweiter Theil, 1887. Wollny, X, p. 460./

AYMONNET. Actinometry. Déhérain, Annales agronomiques, 1878, Tome IV, p. 270, and second note, p. 451. Translated by C. Abbe, Annual Report Chief Signal Officer, 1881, p. 1200.

BAER, K. F. von, und HELMERSEN, G. von. Beiträge zur Kenntniss des Russischen Reiches. Bd. L-VIII.

schen Reiches. Bd. I-VIII.

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