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Thus it took about 1 hour and 45 minutes of human labor to harvest and thresh each bushel. These figures of Brewer are too small, however, as compared with those given by the department of labor for 1830. According to the latter figures it required 2 hours and 32 minutes at that time for the same operations. In 1896, by the use of the combined harvester, this time had been reduced to 5.6 minutes. The cost of human labor per bushel had declined from 15 cents to 2.2 cents. The entire time of human labor necessary to produce one bushel of wheat, including sowing, reaping and threshing, fell from 3 hours and 3 minutes in 1830 to 10 minutes in 1896. In the same period of time the cost of human labor per bushel fell from 17% cents to 3 1-3 cents. The cost of both animal and human labor fell from 20 cents to less than 10 cents. The greatest saving has been in harvesting. The human labor which does remain is quite light compared to that of 1830. This reduction in cost of production represented a saving of about $91,000,000 for the United States on the wheat crop of 1907.

CHAPTER VII.
CROP ROTATION AND IRRIGATION

CROP ROTATION.

The Effects of Continuous Cropping.—Different crops remove from and contribute to the soil elements of different kinds or in different proportions. The availability of plant food is also influenced. Continuously raising one crop tends to exhaust the soil of the food elements available for that crop. In a rotation of crops these effects are not so manifest. Some crops also contribute to the soil elements needed by others, as, for example, leguminous plants fix nitrogen which becomes available for wheat the next year. A rotation involves different methods of cultivation, which are often very effective in eradicating certain weeds. Continuous cropping and cultivation change the physical condition of the soil. This often results, particularly in prairie regions, in the soil blowing and drifting. Rotation of crops, especially when grass is introduced, will soon return the soil to its proper physical condition and prevent blowing. There is little profit in using commercial fertilizers unless rotation of crops is practiced.

Comparative Utility of Crop Rotation.—As a rule the pioneer farmer in a new country never practices much rotation of crops. This is one of the factors of high and intensive farming, which is never found on the frontier. The main reason for this is that land, being plentiful, is cheap, while all other forms of capital, as well as human labor, are comparatively scarce and high. It is but natural for the pioneer to endeavor to diminish those elements entering into the cost of production which are most expensive by substituting others less expensive. Land is the cheapest factor, so he uses this more lavishly, not to say recklessly, and saves the labor and other capital required to farm intensively, which is to cultivate more carefully, to rotate and diversify crops, to keep stock, to fertilize, to irrigate, and to follow many other practices requiring additional labor and capital. This fundamental advantage of extensive farming due to the cheapness and abundance of land is augmented by the fact that the pioneer usually is farming a soil of such virgin fertility that for a number of years it will produce large crops in spite of extensive culture. Often, as has been the case in the United States from the very beginning, when the soil Has lost its fertility so that it will no longer yield standard crops, the farmer leaves the solution of the problem of its further profitable culture to others than himself by removing away from it to settle again upon virgin soil, and to repeat there his previous operations. While labor and all capital except land are higher in price in a new farming country, so little capital is required that its cost is usually below the cost of that required in the older country. In 1860 the United States was a half century behind England in intensive methods of farming, yet the cost of production was much lower for the American farmers than for the most scientific farmer of England, even if the latter paid nothing for the use of his land.1 If most of the members of a community are engaged in agriculture, the supply of agricultural products is not apt to fall below the home demand. Where such a large proportion of the people have an opportunity of producing at cost, home demand is not apt to raise the price greatly above the cost of production of older countries, and exportation is possible. Exportation involves the cost of transportation. Under normal conditions then, prices must always be lower at home than abroad before it will be profitable to export. As long as these conditions obtain, it will be impossible for prices of agricultural products in a new country (generally an exporting country) to be as high as those of an older country. High farming involves more expense than extensive farming, and consequently a larger capital is essential. But as prices cannot be so high in the newer community, and as capital is not so abundant, it follows directly and imperatively that farming cannot be of such a high and intensive grade. Unfortunately, however, as is so frequently the case with the recklessness of plenty, the most loose and careless methods of farming come in vogue, methods that are certain to exhaust the soil to such a degree within a limited number of years as to necessitate either improved methods of culture or its abandonment. While there may be extenuating circumstances in pioneer times which will 1 8th U. R. Census, Agriculture, p. viii.

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.1 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.

1 N. D. Bui. 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 1902.1 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 1 Yearbook U. S. Dept. Agr., 1902, p. 520.

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