DAIRY, SEED IMPROVEMENT, STOCK BREEDERS' MEETINGS. 305 



of soda), eight per cent available phosphoric acid, and no 

 potash. 



Experiments at Massachusetts, however, indicate that avail- 

 able phosp^horic acid hastens the development of the plants at 

 the beginning of the season and that would seem to be borne out 

 by the farmers' experiences cited above, where they had com- 

 pared ten per cent available phosphoric acid against eight per 

 cent available phosphoric acid. The fertilizer companies state 

 that the difference in cost between a fertilizer carrying eight 

 per cent and one carrying ten per cent available phosphoric 

 acid in 1916, will not exceed $1.00 per ton. It may be that 

 this added phosphoric acid may be found profitable. Based on 

 the 191 5 results at Aroostook Farm it would not pay any man 

 to buy potash at the present price of $5 per unit, even if it 

 could be obtained. The increase of ten barrels of potatoes per 

 acre where eight per cent of potash was used over where none 

 was used was worth at harvest about $15. Eight per cent 

 potash, if it could be had, would cost not less than $30 per acre 

 for 1,500 pounds of fertilizer, which is twice the value of the 

 increased crop. 



For potash liberators the evidence is preponderant in favor 

 of nitrate of soda. There is little evidence that common salt 

 frees any perceptible amount of potash which will become avail- 

 able to the potato crop. Gypsum (calcium sulphate) probably 

 will help render the potash available. A fertilizer carrying five 

 per cent of ammonia, in which one-third of the nitrogen is in 

 the form of nitrate of soda, and carrying eight or ten per cent 

 of available phosphoric acid, will have theoretically enough 

 sodium from the sodium nitrate and calcium from the calcium 

 sulphate (gypsum) to liberate enough potash for a maximum 

 crop of potatoes. 



The speaker, therefore, would advise the use of 1,500 to 

 2,000 pounds of a fertilizer carrying five per cent of ammonia, 

 with one-third of the nitrogen in the form of nitrate of soda, 

 and eight per cent or even ten per cent of available phosphoric 

 acid and no potash, for 191 6. With people who- have been get- 

 ting good results from a fertilizer carrying four per cent of 

 ammonia, a 4-10-0 fertilizer would probably prove satisfactory. 



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