Large areas of damp lands, or those covered with swamps, lakes, or shallow arms of the sea, may be made usable if the surplus water can be removed. In England in the eighteenth century the drainage of the fens in the eastern counties marked a new era in agricultural progress. It is estimated that 16,000,000 acres have been reclaimed in the United States, principally in the states of the Mississippi Valley, and most of the soil thus made available to the plow is of unsur passed fertility. The areas of fens, swamps, and marshlands still remaining to be drained comprise about 75,000,000 acres, being about 4 per cent of the area of the country. This would add nearly one fifth to the improved farm area (in Tile underdraining of wet lands is a very enduring sort of improvement which is being made on many thousands of acres yearly. The most extensive work of drainage in the world is that of Holland, where a large part of the surface has been won from the sea. A striking feature of this case is that there is the unceasing need of lifting to the level of the ocean by means of windmills and pumps the natural run-off of rain. Among the larger drainage undertakings in Holland was the draining of the Haarlem Lake in 1840-58, by which 40,000 acres of rich land were made available, and the more recent draining of Zuyder Zee, which added 1,300,000 acres.
Irrigation seeks to supply water to the thirsty land. It is probable that no modern irrigation work (unless it be that of 1 National Conservation Commission Report, 1908-09, Doc. Cons. No. 6399, p. 373. Of the 75,000,000 acres about two thirds are in the south ern states, Florida having about 18,000,000, Louisiana 10,000,000 and other states, Mississippi, Arkansas, Georgia, North Carolina, South Carolina and Texas, ranging from 6,000,000 down to 1,600,000 acres. Over two thirds of the rest is in the group of contiguous states, Indiana, Michigan, Wisconsin, Minnesota, Illinois, Missouri.
the recent Assouan Dam in Egypt) equals that which once was done on the now desert lands between the Euphrates and the Tigris. The opportunities for irrigation, however, in America with its great central desert west of the one hun dredth degree of longitude, are enormous. Already large works have been built by the government and by private enterprise, irrigating 13,000,000 acres, but the national and state governments and private enterprise are entering upon the task on a scale never before attempted. It is estimated that the total area that may some time economically be irrigated is about 45,000,000 acres, enough for nearly a million fifty-acre § 3. Abuse of agricultural land. The forces acting upon the land supply do not all work in the same direction. The land supply shrinks on some sides while it grows in others. The effects of bad husbandry are everywhere in the world apparent, and in many regions fertile fields have been phys ically and economically destroyed. In Asia, lands that once supported millions of people, perhaps tens of millions, are now deserts. Egypt, for a time reduced to a semi-desert condition, has only in the past century been restored to a certain extent by the use of new methods and a return to the old ones. Many of the areas that were the granaries of Rome
can now hardly support a sparse, half-starving population. The land surface remains, but some of the elements indis pensable to its value have been destroyed.
Even in young America may be seen the effect of a failure to keep land in repair. As the new rich lands of the West were opened up, the old lands in the East were allowed to wear out, and many of them were abandoned. Increasing returns marked the spread of the frontier westward. On the new lands in turn the same methods were followed, using up the first rich store of fertility with no attempt to keep up the quality of the soil. This may have been the best policy for 2 Report of National Conservation Commission (1909). Pub. Doc. Consecutive No. 5398, p. 67. Figures for 1908.
the time; it would not have been economical to employ Old World methods of intensive husbandry when such rich ex tensive areas were being opened up. The resulting harvests were in many places phenomenal; in the valley of the James River in Dakota twenty crops of wheat were taken from the same lands with no apparent decrease, and in the black bottom lands of Indiana and Illinois, sometimes overflooded, enor mous crops of corn have been raised still longer without fer tilizer. But the process was one destructive in most places of the natural resources. As settlement moved westward, great forests fell in ashes, and the soil was robbed of the fertile elements which it had taken centuries for nature to store up. What was happening in America and in other new lands in the nineteenth century was the primitive method of exploitation of arable lands (Raubbau, robbery-tillage, as it is expressively called in German). In 1908 there were nearly 11,000,000 acres of abandoned farm lands in the United States and about 4,000,000 acres had suffered from soil erosion as the result of neglects § 4. Means of restoring lost fertility. In the older parts of the United States, as in the older countries, methods have long been employed to maintain the fertility of the soil by returning or increasing certain of the fertile elements. When by neglect of fields the underlying rocks have become denuded of their covering of organic materials, the process of restora tion is most difficult, slow, and costly. The mountain sides have been stripped of forests, and the fertile soil has been washed into the river valleys in many of the older countries as in Greece and Italy, and in many parts of eastern and southern United States. Except in such cases, the soil is a self-replenishing agent, and if allowed to lie fallow, will slowly recover its fertility in whole or in part by disintegration of the subsoil, by slow wearing away of the infertile surface, and by plant action. But self-replenishing of soil is slow. It takes Nature about 500 years to create one inch of fertile a Report of the Conservation Commission, vol. 1, p. 78.