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excuse extensive methods of farming when the future must be forgotten because of present necessities, when many of the advantages of an older society are wanting, and when the burden of public improvements perhaps falls comparatively more heavily, nevertheless such a course long pursued is not only short sighted and suicidal from the standpoint of the individual, but it is also unjust to the future.

When extensive methods of farming have once become customary, changes take place slowly, unless they are necessitated by the growth of population and the exhaustion of the land. These conditions continually repeat themselves in history, for the ancients were already well acquainted with intensive methods of farming.

Summer Fallows.--When land does not produce the usual crops, there is a wide practice of letting it rest one year. No crop is planted, but the land is generally cultivated. This almost invariably results in an increase of yield during succeeding years. It has been claimed that this gain is at the expense of heavy loss in humus matter and available plant food." Fallowing encourages the development of nitrates. One of its greatest advantages is that it enables the soil to store up moisture for the wheat crop of the following year.

Historical.—The farmers of ancient Egypt rotated crops. The same practice was followed in the time of Virgil, as well as the fallowing of land. The three-field system was not new in England in Norman times. It consisted of wheat the first year, barley or oats the second year, and fallow the third year. According to Gibbins crop rotation was not practiced in England in the beginning of the sixteenth century, but the triennial fallow was usual in the first half of the eighteenth century. It was known as the “Virgilian’’ way of farming. Clover and lucern were introduced in the eighteenth century, and brought a new rotation of crops that saved the wasted year during which land used to lie fallow. In the middle of the nineteenth century, rotations were practiced which brought a wheat crop every fourth or fifth year, or twice in 6 years. The Japanese sowed the wheat in rows, and cultivated vegetables between the rows at the same time, in addition to raising other crops before or after the wheat crop on the same ground during the same year.

* N. D. Bul. 24, p. 73.

Before the twentieth century, American agriculture consisted mainly in raising cheap crops, and little attention was given to resulting effects upon the soil. After the soil was robbed of its fertility, various devices were resorted to in order to get a paying crop. The most common of these was to seek new land, or to give the land a rest from production. • Reports from thousands of correspondents show that little systematic crop rotation was practiced in the United States even as recently as 1902. At the close of the eighteenth century the deterioration of the soil became apparent, particularly in Virginia and Maryland, and as early as 1882 it was noticed that the yield of wheat was declining on account of continually cropping this grain on the same land. The most skilled farmers were unanimous in recommending rotation of crops. The most generally advised rotation gave one wheat crop in three years. Under the stress of hard conditions a true conception of the necessity of rotating crops gained a foothold and expanded into farm practice. As would be expected, the longer the occupation, the more developed is the crop rotation. In passing from the east to the west, the degree of rotation begins to diminish in Ohio, and by the time Kansas is reached, it has practically disappeared entirely. One-crop or two-crop production was characteristic of the first agriculture of the north central states.

On the Dalrymple farm of North Dakota wheat was grown continuously for about eighteen years, by which time the soil had been so impoverished that a system of crop rotation and summer fallow became necessary. Generally corn and barley are sown and cut early so that the land may be plowed in July before the wheat harvest. Considerable land is also barren summer-fallowed, in which case it is plowed twice during the summer. In Canada, experience with continuous cropping has been much the same as in the United States. Large areas in different parts of the early settled portions which once yielded fine crops of wheat have been abandoned to pasture and other purposes.

Experimentation.—In experiments in North Dakota, the plots which had been rotated with corn or potatoes yielded about twice as much as the best continuous wheat plot. Good cultivation alone was not sufficient to produce the best crops, and

* Yearbook U. S. Dept. Agr., 1902, p. 520.

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other crops gave a poorer yield on land that had been continuously sown in wheat. “Land which produced three crops of wheat and one cultivated crop in a period of four years, gave almost as much wheat and more profitable returns than did the land which produced four crops of wheat in succession.’’’. Experiments have been made in the continual culture of wheat on a certain piece of ground, there being no fertilizing of any kind, as, for example, the “experimental acre” in Kansas. This trial was begun in 1880, and by 1896 the yield was falling off. Permanent spots of diminished fertility had then appeared. Though they may have been due in part to surface-washing, partial exhausting was undoubtedly a factor.” Historic experiments in growing wheat continuously without fertilizing have been carried on in England for over 50 years. “The yield has fallen to about 12 or 13 bushels to the acre, but for the past 20 years there has been little or no difference in the yield, except slight fluctuations due to seasonal conditions. So far as is known, the soil will produce 12 or 13 bushels to the acre annually for hundreds of years.” " The Crop Rotations of the United States now generally practiced in some typical counties of states leading or promiment in their geographical divisions, are given below: Pennsylvania.—Corn, wheat two years, grass two years (York, Franklin, etc.). Corn, oats, wheat, grass three years (Chester, Westmoreland). Minnesota.--Wheat two years, oats, wheat, flax (Marshall). Corn, wheat two years, oats (Lac qui Parle). Corn, wheat two years, grass two years (Ottertail, Todd, etc.). Washington.—Wheat, rest (Adams). California.--Wheat, rest (Solano, San Joaquin, etc.). Maryland.—Corn, wheat two years, grass two years (Montgomery, Frederick, Talbot, etc.). The rotation on dairy and stock farms includes wheat for only one year.

Oklahoma.--Wheat without rotation (Grant, Garfield, Kingfisher, etc.). Wheat, corn, (Dewey). Wheat three years, oats (Kay).

No crop, nor even any one class of crops, such as the cereals, should be continuously grown on a soil that will produce a variety of crops. On ordinary soils, cereal crops should be rotated every two to four years with a leguminous crop, such as clover or alfalfa. The North Dakota experiment station finds that wheat should have a good place in the rotation because it is a particular crop, and that the average yield of wheat is greatest when the crop follows either corn or potatoes. After these crops, placed in the order that they merit for preparing the soil for wheat, come summer fallow, millet, vetch, peas, wheat and oats. The more dry and unfavorable the season, the more important it was to introduce a cultivated crop into the rotation. The best rotations included a perennial grass, for which purpose brome grass is well adapted to North Dakota. The rotations vary greatly in different states, and soil, climate, and economic causes must determine which rotations are most advantageous for any locality. Summer fallowing is widely practiced on the Pacific coast, largely because there is practically no rotation feasible. Crop Rotations in Foreign Countries.—In Canada, summer fallowing is rapidly becoming general throughout the territories, where the profitable corn crops of the United States cannot be grown on account of the latitude. The system of agriculture most prevalent in Russia is the three-field system, which is universally practiced in the center of the Russian wheat belt. The usual sequence of crops is winter rye, spring wheat and fallow. The arable land is divided into three corresponding parts. At a given time each part is in a different stage of the system. Other crops are being introduced, and this is lessening the area of fallow land. Among the private land owners this signifies progress in agricultural methods. Among the peasants it frequently signifies a harmful overworking of the land, the penalty of which is the drastic retribution of greatly reduced yields. Another system, still more primitive than the three-field one, is also found in Russia, especially in the steppes of the southeast, where the greatest extension of the wheat area is taking place. By this system the land is tilled until it becomes exhausted. It is then allowed to lie fallow in order to recover its fertility. This may require 10, 15, or even 30 years. In Archangel, Olonetz, Vologda, Viatka and Perm, the forest must be cleared to prepare the new land for cultivation, but in the southeastern provinces of Orenburg and Astrakhan, in New Russia, Kherson and northern Caucasia, all that is required is to plow the land. As population grows, this wasteful method of farming is being replaced by the three-field system. Impoverishment of the land by continuous wheat cropping

1 N. D. Bul. 48, p. 735: Bul. 39, p. 458.

* Kan. Bul. 59 (1896), p. 90. * Indus. Com., 10:clxxxviii,

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