590 pounds of nitrogen 1,980 pounds of phosphorus 37,940 pounds of potassium 24,808 pounds of magnesium 31,320 pounds of calcium

“A splendid subsoil,” Percy continued.  “I know of none better in Illinois, except that we sometimes have more calcium in the form of carbonate, and even somewhat more potassium in places; but this must be a fine subsoil for alfalfa, where the bed rock is not too near the surface.  Of course there is but little nitrogen in the subsoil, but that is true of all normal soils, because the nitrogen is contained only in the organic matter, and that decreases rapidly with depth and usually becomes insufficient to color the soil below 18 inches.”

“Now,” began Mr. West, “from these different analyses or invoices, and from your discussion of these results, I take it that you would not advise me to purchase any commercial fertilizer for use on the land we are still using in my rotation; but you think we should make large use of limestone and legume crops.”

“Yes, Sir.  Phosphorus is markedly deficient only in the very level upland which has been allowed to remain uncleared for fifty years or more, and nitrogen is certainly the limiting element on the land you are trying to keep in your rotation.  While you cannot hope to put into your soil any such reserve of slow-acting organic matter as we still have in our comparatively new soils of the West, we may keep in mind that a small amount of quick-acting fresh organic matter is more effective than a large supply of what we might call embalmed material that decomposes very, very slowly unless assisted by the addition of more active organic matter.  It frequently happens that one soil containing a large reserve of old humus, and hence showing more organic carbon and more nitrogen, by the ultimate invoice, than another soil, is, nevertheless, less productive, because the other soil contains a larger amount of fresh organic matter which decays quickly and thus furnishes more nitrogen and liberates more of the other elements from the insoluble minerals of the soil because of the greater abundance of the active products of organic decay.

“I think you should keep in mind, however, that, for every twenty-five bushels of corn you wish to produce, you should return to the soil one ton of clover or four tons of average farm manure, and that for one ton of produce hauled to the barns and fed, you will probably not return to the land more than one ton of manure.”

CHAPTER XXX

“Stone soup”

The next forenoon Percy and Mr. West spent some time making some further tests with hydrochloric acid and litmus paper in different places on the farm; but the result only confirmed the previous examinations.