§ 1. Changes in the land supply. § 2. New land supplies by means of drainage and irrigation. § 3. Abuse of agricultural land. § 4. Means of restoring lost fertility. § 5. Land for products other than food. § 6. Destruction of the natural forests. § 7. Rapid consumption of coal. § 8. Disappearance of mineral stores. § 9. Civilization's consumption of earth's stores. § 10. Land as a site for residence, commerce, and manufacture. § 11. Production of usable land surface in cities. § 12. Dura-tive character of hydraulic power sites. § 13. Goods varying in in-creasableness.

§ 1. Changes in the land supply. The greatest dynamic movements in industry of modern times have been caused by rapid changes in "the land supply," that great complex of area, fertile soil, timber, mineral resources, etc. This seems paradoxical, for "land," "nature," seems to be the one thing (or great group of things) which is fixed in amount. But the economic supply is that which is available in a market. Land in Venus or Mars is of no economic importance to us, but lands on the earth as yet undiscovered or unavailable are a potential supply that, under certain conditions of price and of technic, may be realized.

The discovery of new trade-routes and of new continents in the fifteenth century had immediate economic effects upon Europe, but these began to be more largely felt as actual settlement on these sparsely settled lands progressed in the seventeenth and eighteenth centuries. Pioneers from the most advanced peoples in the world moved on to take up these areas occupied only by small hunting tribes, and to use them by modern agricultural methods. They overcame the first great difficulty of distance, dread, and mystery; they faced and overcame the danger from savages and wild beasts; they cleared the forest, opened paths and highways, and enlarged the supplies of new and fertile lands. They made these lands available to help supply many of the needs of the older countries, just as if the areas of Europe had been increased.

The greatest change came in the middle of the nineteenth century with the use of steamships and the rapid building of railroads in the western states of America. This had an effect upon England and western Europe identical in nature with that which would have been produced had an area touching Europe risen out of the ocean. Every country in Europe has repeatedly felt the shock of these great economic changes which have lowered the price of nearly all kinds of their landed wealth. Because of increasing population (about 1860-1890) the need of land-uses was increasing very rapidly, but the supply of land-uses increased so much more rapidly that it caused the lowering of the value of the older lands in the eastern states of America and throughout Europe, the entire abandonment of some lands for agricultural purposes, and the neglect to repair and maintain a large part of the remainder.

The rate of this movement was more rapid in the nineteenth century than it ever had been, and perhaps more rapid than it will be again; but in some measure such developments will continue for a long period. The land in America for centuries was not, but now has become, for some purposes, a part of the supply in the same market as the land of England. The land in Greenland is not, and probably never can be, an important part of the supply of land in the world; but the tropical lands will doubtless contribute increasingly to the supplies of food and materials used in the temperate zones.

§ 2. New land supplies by means of drainage and irrigation. The habitable globe has now been fully explored and there are no more agricultural lands to discover. There are, however, great areas almost unusable in their natural states that can be made to blossom if properly improved. The greatest possibilities of this kind are in drainage and in irrigation. The improvements consist in insuring just that amount of water needed for cultivated crops.

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 unsurpassed 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 1908).1 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 ihe 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 hundredth 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 farms.2

1 National Conservation Commission Report, 1908-09, Doc. Cons. No. 5399, p. 373. Of the 75,000,000 acres about two thirds are in the southern 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.