48 Report of the Department of Agbon.omy of the 



The figures for the vaiue of increase in the table are obtained by 

 computing corn at 40 cents per bushel, wheat at 80 cents, stover 

 at S3 per ton, straw at $2 and hay at $8. These figures are, of course, 

 much below the market price of these crops, but they are as high 

 as can safely be used in computing net gain from the use of fertil- 

 izers; for it is necessary to make ample allowance for the cost of 

 harvesting and handling the increased crop and for applying the 

 fertilizers. 



The results of these extensive experiments on two widely different 

 soil types in Ohio show that phosphorus when used by itself has been 

 productive of very great increase. But nitrogen and potassium, 

 although they have produced decided increases at Wooster and some 

 increase at Strongsville, have in no case either singly or in any com- 

 bination produced enough increase to make their use profitable. 

 A combination of phosphorus and nitrogen, or phosphorus and potas- 

 sium, or the three together, have at Wooster produced a greater 

 net increase than phosphorus alone; but at Strongsville the opposite 

 is true. The greatest net increase at Wooster has been from the 

 three elements combined. The cost per acre was $23.50 and the 

 net gain $15.63. But when $2.60 invested in phosphorus alone 

 produces a net increase of $13.92 it is hardly profitable to increase 

 the cost to $23.50 for the sake of a net gain of $15.63. A safer 

 investment than this has been $9.10 for phosphorus and potassium 

 in combination. Here the net profit has been $15.09, but the same 

 amount of money invested in phosphorus alone would have been 

 far more profitable. Of course if nitrogen and potassium had been 

 used in somewhat smaller amounts the net profit from their use 

 would have been greater. But phosphorus could no doubt be used 

 in much larger amounts and still give a greater net increase than 

 much smaller amounts of nitrogen and potassium. 



While these experiments show that commercial nitrogen and potas- 

 sium have not been profitable, yet they also show that these soils 

 under the conditions which they have been managed do not furnish 

 enough nitrogen and potassium for good sized crops. They emphasize 

 the importance of supplying nitrogen by the use of farm manures 

 and legumes, and in this way also supply some available potassium 

 and help to make a large amount available from the supply already 

 in the soil. 



Pennsylvania experiment. — Extensive fertilizer experiments have 

 been conducted by the Pennsylvania Experiment Station since 

 1882. They have been carried out on different fields with four 

 different crops each year; corn, oats, wheat and hay (clover and 

 timothy) being grown in each rotation. Results covering 25 years' 

 work are published in Bulletin 90 of the Pennsylvania Station, 

 The following table is derived from data in that bulletin. 



