Under a good system of crop rotation with all grain sold from the farm it is possible to return to the soil more than one-third of the phosphorus and more than one-half of the organic matter contained in the crops, and even as much nitrogen as all of the crops remove from the land in the grain sold.  Thus, with a four-year rotation of wheat, corn, oats, and clover, and a catch crop of clover grown with the wheat and turned under late the following spring for corn, we may plow under three tons of clover containing one hundred and twenty pounds of nitrogen, in return for the one hundred and nineteen pounds removed from the soil for the twenty-five bushels of wheat, fifty bushels of corn, and fifty bushels of oats.  These amounts of grain and the two bushels of clover seed might be sold from the farm, while the two and one-half tons of straw, one and one-half tons of stalks, and three tons of clover might be returned to the land.  These amounts aggregate seven tons of organic matter, or the equivalent of seventeen tons of manure, measured by the nitrogen content, or of twenty-four tons, measured by the content of organic matter.  To replace the twenty-two pounds of phosphorus sold from the farm in the grain of these four crops would require the expenditure of sixty-six cents at the present prices for raw phosphate delivered at Heart-of-Egypt.

I have no doubt you will be glad to have your attention called to the fact that the world does not live wholly, or even largely, upon meat and milk.  Bread is the staff of life, and I note from your World’s Work article that you prefer to have the bread made of wheat.  Thus, most farmers must raise and sell grain and vegetables.

If no independent system of live-stock farming can add a pound of phosphorus to the one hundred and sixty pounds still remaining in the great body of the level uplands constituting forty-one per cent. of St. Mary county, and forty-five thousand seven hundred and seventy acres of Prince George county, Maryland, adjoining the District of Columbia, nor even maintain the phosphorus supply in our good lands, then what must we do to be fed?

Manifestly, we should make large use of legume crops for the production of farm manure or green manure; and, manifestly, America should stop selling every year for five million dollars enough raw phosphate for the production of more than a billion dollars’ worth of wheat.  How long can we afford to give away a thousand millions for five millions?

Our annual corn crop is nearly three billion bushels, while the estimated value of all the timber on the still remaining federal lands is only one billion dollars.  Again, our three trillion tons of coal is sufficient for an annual consumption of half a billion tons for six thousands years, whereas the United States Geological Survey has estimated that at the present rate of increase in mining and exportation our total supply of high-grade phosphate will be exhausted in fifty years.  It seems to me that about ninety per cent. of the talk about conservation of natural resources is directed toward ten per cent. of the resources, when we remember the soil as the foundation of all agriculture and all industry.