the system of rotation, a cereal crop is followed by a so-called green crop, the roots of which penetrate deep into the subsoil and extract from it a fresh supply of the needful minerals; thus the vigor of the surface soil is renewed and it again produces an abundant grain crop.
The fundamentals of the new rural economy are to secure maximum productiveness on the agricultural lands, as a whole, by a comprehensive utilization of a great variety of fertilizers, and, by studying the needs of the soil, to apply to them the particular fertilizers best adapted to their nature. The demonstrations of experimental chemistry in these directions have been so effective that agricultural science has become one of the leading subjects of practical investigation, receiving the actual encouragement of all civilized governments. The energetic spirit stimulated by the latest teachings of chemical science has reflected constant advance in all other departments of scientific agriculture, such as drainage, irrigation, the improvement of breeds and plants, meteorology, etc.
Agricultural Interests and the Government.—The growth of agriculture and the evolution of enlightened governmental administration have uniformly gone hand in hand. The great distinguishing characteristic of the Dark Ages in Europe was the crushing oppression of the rural population. The lifting of the arbitrary burdens resting on the agricultural class has in all countries marked the beginning of the era of enlarged civil liberty and of diffused intelligence. The marvelous progress of the United States is above all the result of the rapid absorption of lands by its own native citizens and by industrious immigrants from Europe. From the earliest period the Federal Government, having enormous tracts of unoccupied lands at its disposal, pursued an extremely liberal policy to encourage settlement. Thus, in a brief time, every section of the country was peopled and the foundations of a great commonwealth were laid. With the vigorous revival of enterprise and thrift after the Civil War, and the steady advance of immigration, the epoch of abundant, fertile lands obtainable for a nominal price was brought to its close; and the intense rivalry witnessed at the opening of Oklahoma Territory was a demonstration of the practical termination of the era of settlement. In a new country, the soil of which has been accessible to all, the farmers have not been prompt to turn their attention to the strictly scientific aspects of agriculture, yet the government has manifested appreciation of the spirit of the age and the needs of the future by its generous provisions for the founding of agricultural colleges, and by its admirable system of agricultural experiment stations. The latter, like the agricultural colleges, are modeled upon the technical institutions originated in Europe for scientific investigation concerning all the branches of agriculture. The Federal Government makes an annual grant for experiment station purposes to each State and Territory in which an agricultural college is in operation, and some of the States also contribute to the support of the stations. The Department of Agriculture of the National Government is excellently equipped for the promotion of agricultural interests in both practical and experimental aspects. Its Weather Bureau, Bureau of Animal Industries, and various divisions, are constantly performing work of much value, and a great variety of useful information is systematically disseminated.
The following tables give the acreage, value, and production (000 omitted) of the principal agricultural crops in 1919:
BARLEY
| State | Acreage | Production | Total farm value |
| Acres | Bushels | Dollars | |
| Maine | 6 | 168 | 286 |
| New Hampshire | 1 | 25 | 47 |
| Vermont | 14 | 420 | 630 |
| New York | 113 | 2,486 | 3,381 |
|
Pennsylvania |
16 | 392 | 502 |
| Maryland | 6 | 198 | 244 |
| Virginia | 15 | 375 | 488 |
| Ohio | 125 | 3,150 | 3,938 |
| Indiana | 55 | 1,430 | 1,687 |
| Illinois | 212 | 5,724 | 6,926 |
| Michigan | 280 | 5,320 | 6,278 |
| Wisconsin | 512 | 13,568 | 16,417 |
| Minnesota | 910 | 18,200 | 21,112 |
| Iowa | 315 | 8,032 | 8,996 |
| Missouri | 11 | 330 | 429 |
| North Dakota | 1,300 | 14,950 | 16,146 |
| South Dakota | 875 | 19,250 | 22,138 |
| Nebraska | 217 | 5,577 | 5,577 |
| Kansas | 600 | 16,200 | 16,200 |
| Kentucky | 4 | 100 | 157 |
| Tennessee | 8 | 176 | 317 |
| Texas | 25 | 875 | 980 |
| Oklahoma | 50 | 1,500 | 1,830 |
| Montana | 90 | 540 | 756 |
| Wyoming | 35 | 525 | 919 |
| Colorado | 200 | 3,900 | 4,680 |
| New Mexico | 20 | 680 | 748 |
| Arizona | 29 | 1,102 | 1,543 |
| Utah | 24 | 720 | 1,015 |
| Nevada | 12 | 420 | 630 |
| Idaho | 120 | 3,360 | 4,704 |
| Washington | 138 | 4,140 | 5,589 |
| Oregon | 82 | 1,886 | 2,829 |
| California | 1,000 | 30,000 | 42,300 |
| United States | 7,420 | 165,719 | 200,419 |
