Acid phosphate was also used in direct comparison; and, in answer to the question whether the general farmer should apply liberal amounts of finely ground natural rock phosphate, or whether he should pay four times as much for phosphorus after the fertilizer manufacturer has mixed one part of the raw rock with one of sulfuric acid and thus produced two parts of acid phosphate, these Pennsylvania experiments tell us that the yearly average for the twelve years gave a gain per year of $2.45 from the raw phosphate and 48 cents from the acid phosphate, at the prices used by the Pennsylvania Experiment Station.  But we must not draw general conclusions from this one experiment, even though it covers twelve years.

In 1895 the Maryland Experiment Station began field experiments with different forms of phosphorus; and, as an average of six tests every year for twelve years, $1.965 invested in ground raw rock phosphate produced increases in corn, wheat and hay that were worth $22.11, at 35 cents a bushel for corn, 70 cents for wheat, $6 a ton for hay, and 3 cents a pound for phosphorus in the ground natural phosphate.  How would you like 1000 per cent profit as the result of mixing brain with brawn, in connection with the improvement of your own business, thus keeping the investment under your own control?

Mind you, this does not prove that farming is profitable, but only that the intelligent use of phosphorus in farming is profitable.  In other words the admixture—­brains—­is profitable.

In commenting upon his investigations the director of the Maryland Agricultural Experiment Station states that the raw phosphate produced a higher total average yield than acid phosphate, and at less than half the cost.

The Rhode Island Experiment Station began a series of experiments with different forms of phosphorus in 1894.  If we add together all the hay and grain crops grown during the decade following the first year of these experiments, we find that the increases per acre were 14,580 pounds for raw phosphate and 14,550 pounds for acid phosphate, on unlimed land; while lime and raw phosphate produced 27,030 pounds, and lime and acid phosphate 29,690 pounds, of increase; and the acid phosphate cost three times as much as the raw phosphate.

In commenting upon these investigations the director of the Rhode Island Experiment Station states that the raw phosphate gave very good results with such farm crops as oats, peas, crimson clover, millet, soy beans, and so forth, but very poor results with such garden crops as turnips, rutabagas, cabbage, beets, lettuce, squash, and so forth, and its use for these garden crops is not advised.

In 1890 the Massachusetts Experiment Station began investigations with different phosphates applied in equal money value, and in his report for 1900 the director states that the raw rock phosphate ranks above the acid phosphate both as an average for the entire period and as an average between 1895 and 1900, during which time the land to which no phosphorus was applied produced only 55 per cent as much as where raw phosphate was used—­a result worth every farmer’s consideration.