New York Agricultural Experiment Station. 



49 



Table III. — Effect of Fertilizer Elements and Combinations in 

 Pennsylvania Experiments. 



Here in another state on a widely different soil type we have in 

 general the same story as is revealed in the Ohio experiments. 

 Phosphorus is the first limiting element of plant food. Nitrogen 

 or potassium without phosphorus does not materially increase the 

 yields and is used at an entire loss. In combination with phos- 

 phorus they decidedly increase the yields, though at heavy expense. 

 The most profitable combination has at a cost of $14.80 given a net 

 profit of $9.26. But $4.80 invested in phosphorus alone has given 

 a net profit of $6.54. 



These experiments have been conducted on a clay loam soil and 

 no effort, other than the use of the clover and timothy sod, has 

 been made to supply the organic matter so much needed for good 

 physical condition and to aid in making plant food available. If 

 organic matter had been supplied in fair amounts more nitrogen 

 would have been furnished in this way and more potassium made 

 available, thus rendering it still less profitable to purchase them. 

 And in the light of other experiments we know that under such con- 

 ditions phosphorus would give greater returns. 



These Ohio and Pennsylvania experiments are the most extensive 

 long-time fertilizer tests that have been conducted in this country. 

 Attention is again called to the fact that they have been conducted 

 on three widely different soil types. In Pennsylvania the experi- 

 ments have been on a residual clay-loam soil of limestone origin. 

 At Wooster, Ohio, it is a silt-loam hill-land soil of glacial origin, 



