No. 7. DEPARTMENT OF AGRICULTURE. 



COMMERCIAL. FERTILIZERS vs. YARD MANURE. 



401 



Alternate Years. 



None 



P 



P and K 



P. K and N 



Yard manure, six tons, 



13 96 

 8 68 

 6 64 



13 96 



•Estimated at one dollar per ton. 



Average value of products from 25 four years' rotations, Pennsyl- 

 vania Experiment Station, State College. 



In making this comparison an arbitrary value of |1 per ton has 

 been placed upon the stable manure. In estimating the cost of 

 commercial fertilizers, phosphoric acid has been valued at five cents 

 a pound, potash at four cents a pound, and nitrogen at eighteen 

 cents a pound. Assuming these values to be correct, the best com- 

 mercial returns have been made by the use of yard manure, the next 

 best by the use of phosphoric acid and potash together, next a com- 

 plete fertilizer containing 24 pounds of nitrogen per acre, and fourth 

 by the use of phosphoric acid alone. The amount of potash used 

 has been somewhat excessive and it is believed that probably 

 equally good results would have been obtained by a less amount, 

 perhaps half the amount of potash. If this is true, then relatively 

 better results would be indicated from the use of phosphoric acid 

 and potash or by the use of a complete commercial fertilizer con- 

 taining potash. 



EFFECT OF LIGHT APPLICATIONS OF YARD MANURE, 



Comparatively light applications of yard manure applied on alter- 

 nate years, namely, to the corn and the wheat, have produced 

 marked increase in yield compared with plats receiving no fertilizer 

 of any kind. This table emphasizes the importance of light applica- 

 tions of yard manure when applied as frequently as once in two 

 years. The same facts are brought out in the table showing values 

 of four years' rotations by five year periods. The first column shows 

 the plats which received no fertilizer. It will be noted that there 

 has been a decrease from |7o for the average of the first five years 

 to approximately |50, while where six tons of yard manure has been 

 applied in alternate years the value of the products of a four years 

 rotation for the first five years was .fS7, as compared to nearly |92 

 the last five year period. 



26—7—1908. 



