« AnteriorContinuar »
pathogenic ferments, which may subsequently infect the health of man and beast. These ferments may attach themselves to-vegetables and thus enter the animal organism, or they may remain with a suspended vitality for an indefinite period in the soil and awaken to pernicious activity when a favorable environment is secured.''
Vast stores of fertilizing materials are continually being washed from the earth by floods, and carried away by streams and rivers. The Seine river thus annually carries two million tons of silt, a greater weight than the merchandise which its waters transport. The Var carries seaward yearly 23,000 tons of nitrogen, and one cubic meter of water per second from this stream could be made to produce crops valued at 35,000 francs each year. The river Durance, an Alpine stream, annually carries silt, the fertilizing power of which is equal to 100,000 tons of stable compost or. excellent guano. It would take 119,000 acres of forest trees to yield the carbon that this volume of silt contains.
Effect on Germination. In general, fertilizers never seem to aid in the germination of seeds, and may be harmful if used in large quantities. One per cent of muriate of potash, or of sodium nitrate, is very detrimental, whether applied directly, or mixed with the soil. Phosphoric acid and lime are much less injurious, and may be harmless if not used in excess. It is safest not to bring commercial fertilizers into immediate contact with germinating seeds, and the effect of chemicals applied to seeds before they are planted is no index of their action in this respect when used as fertilizers. When injury does result, it is chiefly to the young sprouts during the time between when they leave the seed coat and when they emerge from the soil, the seed being affected but slightly, if at all. Salts injurious to wheat seedlings have been given in the following order: Magnesium sulphate, magnesium chlorid, sodium carbonate, sodium sulphate and sodium chlorid. Different varieties of wheat vary in their ability to resist the same toxic salt, as does also one variety in different salts.
Effect on Yield and the Supply of Plant Food.—There seems to be a certain minimum yield of wheat which a soil will give
under continuous cropping and ordinary cultivation, and this yield can be increased by rotation of crops, and still more by improved methods of cultivation. Fertilizing is also a factor which generally increases the yield, whether utilized by itself, or in conjunction with other factors. The use of commercial fertilizers must, however, be accompanied by intensive methods of cultivation in order to be profitable, and now and then the returns seem to diminish with continued use. Mr. Whitney, chief of the bureau of soils in the United States department of agriculture, maintains that he never saw a case of soil exhaustion which was probably due to the actual removal of plant food. He considers the so-called worn-out soils of the United States due to conditions which make the plant food unavailable, and holds that the primary object of fertilizing is the adaptation of soils to any desired crop or crops. Fertilizing can also be practiced to force growth, even on rich soil. Texture and drainage of soils can be improved, the ratio of soil constituents balanced, and acidity neutralized. Attention is called to the facts that “the soils of India, which tradition says have been cultivated for 2,000 years, under primitive methods, without artificial fertilizing, still give fair returns. In Egypt, lands which have been cultivated since history began are as fertile as
In Europe there are records of cultivation of soils for 500 years." 1
Tradition is not always scientific, however, and soil is not greatly taxed by such primitive methods of culture as have existed in India for 2,000 years. The sediment which is deposited by the waters of the Nile at every annual overflow is entirely adequate to maintain the fertility of the cultivated lands of Egypt, while fertilizing, improved methods of cultivation, and crop rotation have greatly increased the yield of European soils. On some of the fields in France 28 bushels of wheat are raised per acre where 17 bushels were raised 50 years ago. The soil of France is more fertile today than it was in the time of Cæsar. The fertility of the scil in Germany has increased proportionately. In England, land on which wheat was grown continuously for 50 years without fertilization yielded 12 to 13 bushels per acre, while adjacent plots to which fertilizers were applied averaged about 30 bushels per acre. Mr.
1 Industrial Commission, 10: clxxxviii, cxcii.
Whitney takes the position that if the soils of eastern and southern United States have any less plant food than when first cultivated, they at least have all the ingredients essential for crop production. This position is certainly supported by statistics that have been given on the amount of plant food contained by soils. An acre of very fertile soil contains about 70,000 pounds, or 2 per cent, of potash in the first foot of ground. A crop of wheat removes about 15 pounds of potash from each acre. It has been estimated that the first eight inches of soil contain on an average enough nitrogen to last 90 years, enough phosphoric acid to last 500 years, and enough potash to last 1,000 years. This supply is materially increased when we consider the great depth 'penetrated by the roots of wheat. It must also be borne in mind that the loss of plant food is often much greater than that removed by crops; for example, it has been given as three to five times as much in the case of nitrogen.
Extensive farming, nevertheless, soon reduced the productivity of our first cultivated soils, and with the cpening of the large and level western wheat fields of fully as great fertility as was ever possessed by any soils of the United States, many of the older lands were abandoned. Now, however, most of the farm lands of the west have 'een occupied, the standard of farming is being raised, and conditions have so changed as to make it seem profitable again to resume the cultivation of these abandoned lands. But they must be farmed by intensive methods, of which fertilizing is a valuable part. Some lands have already been restored to fertility and are being cultivated with profit.
Missouri soils are still rich in plant food, yet their productivity is much less than it was 50 years ago. Commercial fertilizers had been profitably used in wheat raising in Ohio over a decade ago. Growing a leguminous crop on light sandy soil deficient in humus increased the yield of the following crop of wheat over 50 per cent in Arkansas. When 400 pounds of a complete fertilizer were used in addition, the following 2 years the wheat crop averaged over 70 per cent more than on soil not thus treated. Manure treatment and the application of phosphorus is found very profitable in Illinois.
1 Rept. Mich. Board Agr., 1905, p. 147.
As a rule, the land in the Red river valley is not fertilized, and produces less than 15 bushels per acre, but the application of fertilizers has given 26 bushels per acre. Rotation of crops is already widely practiced in the northwest, and as the soil becomes more exhausted and the prices of land and produce rise, fertilizers will be used there, just as they have in every other country where similar conditions arose. Even the largest bonanza farmers are looking forward to the time when they must fertilize. Stock will also be raised, and farming will become more diversified. This will give opportunity to utilize many of the products of wheat on the farms where they are produced, and the need for commercial fertilizers may ultimately be removed altogether. One-fourth of the nitrogen and nearly all of the phosphoric acid and potash which enter into a crop of wheat are contained in bran, screenings and middlings. Most of these can be returned to the soil by raising stock. These principles are not mere theories, for their practical working has been demonstrated in Michigan and Illinois, in portions of which the land has been continually growing more fertile under cultivation. without the use of a pound of commercial fertilizer.
The average Kansas wheat grower has given little thought yet to fertilizing, but “his methods will change with the years and the necessities.” In Minnesota, “results already reached warrant the statement that the average yields per acre of wheat can be increased 25 to 50 per cent by so rotating the crops and manuring and cultivating the fields (as) best to prepare the soil for this grain."1 The necessity of fertilizing is little felt in Canada as yet.
Fertilizer Laws.-A majority of the United States, including nearly all the states east of the Mississippi, have statutes, most of them rather stringent, governing the sale of commercial fertilizers. That dealers were cheating farmers was first shown by the Massachusetts experiment station. This station was instrumental in the passage of the Massachusetts fertilizer law, which was more or less closely followed by other states. The department of agriculture has made efforts for a more uniform system of laws, and to regulate interstate trade. No general fraud is now practiced. Thousands of official analyses are
1 Minn. Bul. 12, p. 321.
made yearly, and these very largely eliminate fraud and extravagant claims.
Fertilizer Statistics.—The annual sales of fertilizers in the United States exceed $50,000,000, and perhaps over 2,000,000 tons are consumed. During 1896 over 375,000 tons were imported, valued at about $19 a ton, and over 514,000 tons, valued at about $8.50 a ton, were exported. During the first six months of 1905 the importations were valued at nearly $2,000,000. The annual import of nitrate of soda is nearly 200,000 tons, having an average value of about $30 a ton. The first guano sold for about $95 a ton, but later fell to half that amount. A ton of cottonseed meal has a fertilizing value of over $20. A ton of fertilizer, costing $25, is applied to an acre of wheat land in New York. The phosphate mined in the United States in 1899 amounted to 541,645 tons. The average cost of phosphates at the quarry was $4.42 per ton in 1893. In Illinois rock phosphate could be procured at about $8 per ton in 1906, and bone phosphate at $25 per ton. California expended six times as much for fertilizers in 1900 as in 1890. About 1890 the farmers of Ohio were expending a million dollars annually for commercial fertilizers used in the production of wheat.
It is claimed that a trust caused prices of fertilizers to advance from 15 to 25 per cent in 1900. Below is a schedule of prices given for the different fertilizing substances per pound:Nitrogen
.1614 cents Potash
5 cents Water-Soluble Phosphoric Acid
51/2 cents Citrate-Soluble Phosphoric Acid
5 cents Phosphoric Acid in fine bone
3 cents Phosphoric Acid in medium and coarse bone. .212 cents
In Illinois the annual cost of fertilizing an acre of land is about $1.70. Tubercle organisms enable leguminous crops to add from $8 to $10 per acre in nitrogenous fertilizer. In the early nineties over 75 per cent of the fertilizers sold were equal to or above the guaranty under which they were sold. Most of the others were much less than 1 per cent below their guaranty. It has been estimated that with the use of all barn manures and proper cultivation, the soils of the Red river
1 Miss. Bul. 77 (1902), p. 3.