"Those results are all reported in Bulletin No. 54 of the Bureau of Soils," said the Chemist, "and I have extra copies right here and will be glad to present you with one. And let me give you our Bulletin 22 also. This will enable you to get a clear idea of the principles we are developing which are solving the soil fertility problems that have completely baffled the scientists heretofore." CHAPTER XXIII MATHEMATICS APPLIED TO AGRICULTURE PERCY left the Bureau of Soils with a feeling of deep appreciation for the uniform courtesy and kindness that had been accorded him, but with a firm conviction that the laboratory scientists were too far removed from the actual conditions existing in the cultivated field. He sought the quiet of his room at the hotel in order to study the bulletins he had received. Even with his college training he found it difficult to form clear mental conceptions of the results of investigations reported in the bulletins. Sometimes the data were reported in percentages and sometimes in parts per million. No reports gave the amounts of the element phosphorus; but PO4 was given in some places and P2O5 in others. In Bulletin No. 22, the potassium and calcium were reported as the elements and the nitrogen in terms of NO3, while potash (K20), quicklime (CaO), and magnesia (MgO) were reported in Bulletin 54. By a somewhat complicated mathematical process, he finally succeeded in making computations from the percentages of the various compounds reported in the soil separates and from the percentages of these different separates contained in the soils themselves and from the known weights of normal soils, until he reduced the data to amounts per acre of plowed soil. He was especially pleased to find that the essential data were at hand not only for both the Leonardtown loam and the Porter's black loam, but also for the Norfolk loam, which he had learned from one of the soil maps was the principal type of soil southwest of Blairville on Mr. Thornton's farm; and, furthermore, the Miami black clay loam of Illinois was included. Percy knew the black clay loam was a rich soil, for the teacher in college had said that the more common prairie land and most timber lands were much less durable and needed thorough investigation at once, while the flat recently drained heavy black land could wait a few years if necessary. Percy first worked out the data for the Miami black clay loam. The chemist had analyzed the soil separates for only four constituents, and they showed the following amounts per acre of plowed soil to a depth of six and two-thirds inches, averaging two million pounds in weight: 2,970 pounds of phosphorus 38,500 pounds of potassium 18,440 pounds of magnesium 46,200 pounds of calcium He then made the computations for the average of the Leonardtown loam of St. Mary County, Maryland, with results as follows: 160 pounds of phosphorus 18,500 pounds of potassium 3,480 pounds of magnesium