the development of our own soil, for in that case we must become physically self-supporting.

The pent-up versus the expanding type of civilization. Even though we aim to become physically self-supporting we have two distinct lines of development open to us: one is to develop an oriental, or pent-up, type of civilization; the other is to develop an occidental, or expanding, type of civilization. By an oriental, or pent-up, type of civilization is meant one in which we try to live on our existing area of land and to support a growing population without adding to our productive area. This leads to a gradually increasing intensity of cultivation and a gradual lowering of the standard of living of those who work on the soil, and eventually of the masses of the people. By an occidental, or expanding, type of civilization is meant one in which the effort is made to maintain the standard of living and the product per man in a growing population by widening our cultivated area rather than by cultivating the original area more intensively. If we had been developing a pent-up civilization we should never have spread, say, outside of the original thirteen states, but should have tried to support our increasing numbers by cultivating the soil more and more intensively. Indeed, we should probably not have left Europe in the first place, unless it had been to escape persecution. We have preferred to expand over more land rather than to try to live on the original area, whatever that original area might have been. It is difficult to see where this tendency will lead us, but it is a rather striking fact that from the Greeks down to the nations of the present every great European nation has been a colonizing nation. Thus people have preferred to go where land was abundant rather than to stay where population was dense. Unless we change our habit very decidedly we shall try to maintain our standard of living. When this cannot be achieved by intensive cultivation we shall swarm or send out colonists; that is, some people will emigrate. The only alternative would be the maintenance of a stationary population through birth control.

The table on the following page shows, roughly, the area of land which it takes to produce, under fairly good agriculture, the food of a soldier for a year.

This does not take into consideration the land necessary to clothe him or to feed the horses which are used to cultivate the land. If we assume that an average family of five persons will consume as much as do three soldiers, we shall conclude that it takes nine acres to produce food for a family. Besides, the land must grow feed for the horse that plows and cultivates it. According to the United States Census, in the great farming area of the upper Mississippi Valley there is one farm horse for every thirteen acres under cultivation. If, to be fairly liberal, one horse is sufficient to cultivate on the average fourteen acres, we might conclude that one horse could furnish the power necessary to cultivate enough land to grow the food for one family (nine acres) and for himself besides (five acres), or a total of fourteen.

The yields assumed in the table on page 255 are not unusually large, being about the same as those in England and other well-cultivated countries; but they are about twice the average yields in this and other new countries.

One very important part of the problem of economizing land is that of preserving and improving its present fertility. This is to be done mainly by careful management of the soil. Crop rotation, a proper balance between plant-growing and animal husbandry in order to supply natural manure, and an increased use of chemical fertilizers are the main parts of a policy of soil conservation. How important an item natural manure is in our national economy may be shown by the following facts: It has been conservatively estimated1 that the value of the animal manure of the country exceeds two billion dollars ($2,225,700,000). This is greater than the combined value of all the mineral output and the entire timber cut of the country at the time the estimate was made. If one third of this is wasted, it amounts to a sum much greater than the value of the

1 Farmers' Bulletin 192, p. 5, United States Department of Agriculture.

entire timber cut of the country. Clearly the conservation of our animal manure is one of our greatest conservation problems.2 The increasing use of chemical fertilizers, however, is necessary if we are to make increasing drafts upon the soil in order to feed our increasing population.

1 Cf. "United States Army Regulations, 1913" (corrected to April 15, 1917), paragraph 1205, p. 240. Government Printing Office, Washington, 1917.

2" The Organization of a Rural Community," Yearbook of the United States Department of Agriculture, 1914.

CHAPTER XVII

THE BALANCING OF THE FACTORS OF PRODUCTION

Balanced rations, fertilizers, etc. Every farmer nowadays is familiar with the idea of a balanced ration for his live stock and a balanced fertilizer for his soil. Students of human dietetics also are familiar with the idea of a balanced ration for man. By a balanced ration is meant one which contains the different food elements in the proportion in which the body needs them. By a balanced fertilizer is meant either one which contains the different elements of plant food in the proportion in which plants need them, or one which will balance up the soil and put into it the elements of plant food which it lacks. Thus, a soil that is rich in nitrogen but deficient in potash would need a fertilizer that was particularly rich in potash. Not long ago the writer was at the home of a professor of agriculture in one of our leading agricultural colleges. The grass was growing up between the bricks in the sidewalk in front of the agriculturist's house. As a demonstration he was using fertilizer to kill the grass. It was excellent fertilizer, and in the proper relation it would have made the grass grow more luxuriantly. He simply put on too much, and the result of the bad balance was to kill the grass. In addition to those elements of plant food which ordinarily go into the fertilizer, moisture and other factors are required. If there is too much of one and too little of another factor, plants will not grow. Everyone is familiar with the fact that on swampy land plants will not grow because there is too much water, and that on desert land they will not grow because there is too little.

Balanced ingredients. All these facts are mentioned to make it perfectly clear to the student that in almost any line of

production the question of the balance of factors is a very important one. All the factors may be present, but if they are not in the right proportions, production will be reduced or even destroyed. This is true not only of the elements of plant and animal growth, which are agents of production, but of tools, implements, raw materials, and other things which enter into a mechanical industry. In the manufacture of oldfashioned gunpowder, for example, charcoal, saltpeter, and sulphur were required, and they had to be combined in fairly definite proportions. If it happened that there was more charcoal on the market than would combine with the limited supply of one of the other ingredients, say saltpeter, the production of gunpowder was limited by the small supply of saltpeter and not by the supply of charcoal. Only as much gunpowder could be manufactured as the small supply of saltpeter would permit. In the making of old-fashioned mortar, lime and sand were required. Too much of either one or too little of the other would spoil the mortar. If in any given situation there should happen to be a scarcity of sand, very little lime could be used, because only as much mortar could be made as the limited supply of sand would permit. Again, however abundant both lime and sand might be for the making of mortar, if brick and stone were scarce, very little mortar could be used, and there would, therefore, be very little productive demand for sand and lime.

Balanced agents of production. This principle applies not only to the raw materials which are used in various lines of production but to the active agents themselves, such as labor. However numerous the hodcarriers might be, if there were a scarcity of brick and stone masons not many hodcarriers could be used. The farmer who had plenty of land and tools, but no horses, oxen, or tractors, would not be able to use either his land or his tools effectively. If he could not raise the money in any other way, it would pay him to sell some of his tools or some of his land and buy horses in order to restore the balance. At bottom this is much the same problem as that of balancing rations or fertilizers. Again, however much land he might