USE OF PHOSPHORUS IN DIFFERENT FORMS 277 



In the other phosphate experiment by the Maine Station, cover- 

 ing five years on a lo-acre field divided into four 2^-acre plots, the 

 fertilizer applications were made but once (in 1890). The amounts 

 applied per acre were 20 loads of stable manure on plot i, and 66 

 pounds of sodium nitrate, 16 pounds of ammonium sulfate, and 100 

 pounds of potassium chlorid (supplying only 14 pounds of nitro- 

 gen and 42 pounds of potassium) on plots 2 and 3. In addition, 

 plot 2 received 1000 pounds of raw rock phosphate (containing 107 

 pounds of phosphorus), and plot 3 received 500 pounds of acid 

 phosphate (containing 35 pounds of phosphorus), per acre. Plot 4 

 received no fertilizer. 



Table 47 gives the results obtained for the five years of the 

 experiment, and also the average yields of hay for two years before 

 the fertilizers were applied. 



TABLE 47. MAINE EXPERIMENTS WITH EQUAL MONEY VALUES OF RAW 



PHOSPHATE AND ACID PHOSPHATE 

 Pounds per Acre of Air-dry Produce 



