“These bacteria have power to furnish very large amounts of nitrogen to such a crop as alfalfa.  The Illinois Station reports having grown eight and one-half tons of alfalfa per acre in one season.  It was harvested in four cuttings.  The hay itself was worth at least $6 a ton above all expenses, which would bring $51 an acre net profit for one year.  Of course this was above the average, which is only about four and one-half tons over a series of several years.  But suppose you can save only three tons and get $6 a ton net for it, as you could easily do by feeding it to your cattle and sheep.  That would bring $18 an acre or six per cent. interest on $300 land.  I am altogether confident that this could be done on your sloping hillsides, with their rich supplies of phosphorus and other mineral foods, provided, of course, that you use plenty of ground limestone and thoroughly inoculate the soil.”

“Well, I shall certainly try alfalfa again,” said Mr. West, “and if I can grow such crops of alfalfa as you think on the hillsides, I can have much more farm manure produced for the improvement of the rest of the land.  By the way what did that chemist find in that sample you took of the other land where it does not wash so much as on the steeper slopes.”

“He found the following: 

1,030 pounds of nitrogen 1,270 pounds of phosphorus 16,500 pounds of potassium 7,460 pounds of magnesium 16,100 pounds of calcium

“Well, the phosphorus is not so low,” said Mr. West.

“Fully equal to that in our $150 Illinois prairie,” replied Percy, “and again the calcium is more than ours, with magnesium not far below, and potassium half our supply.  Nitrogen is plainly the most serious problem on most of this farm, and limestone and legumes must solve that problem if properly used.”

“Do you think this land could be made as valuable as the Illinois land just by a liberal use of limestone and legumes?” asked Adelaide.

“I should have some doubt about that,” Percy replied.  “Your very level uplands that neither lose nor receive material from surface washing are very deficient in phosphorus and much poorer than ours in potassium and magnesium; and your undulating and steeply sloping lands are more or less broken, with many rock outcrops on the points and some impassable gullies, which as a rule compel the cultivation of the land in small irregular fields.  A three-cornered field of from two to fifteen acres can never have quite the same value per acre as the land where forty or eighty acres of corn can be grown in a body with no necessity of omitting a single hill.  Then there is some unavoidable loss from surface washing, so that to maintain the supply of organic matter and nitrogen will require a larger use of legumes than on level land of equal richness.  In addition to this is the initial difference in humus content.  This is well measured by the nitrogen content.  While your soil contains eight hundred pounds of nitrogen