“And have you also determined the percentages of sand, silt, and clay in the soils themselves?”

“Oh, yes, the physical composition of the soil is a matter of very great importance, and this is always determined and reported for every soil.  Did you not see that in the Reports you examined this morning?”

“I think I did notice it,” Percy replied, “but it is so easy for the farmer himself to tell a sandy soil from a clay soil that I did not appreciate the value of those physical analyses.

“In any case, I shall be very glad to know what results were obtained from the chemical analysis of the soil separates to which you referred.”

“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.