PHOSPHATES IN MASSACHUSETTS AGRICULTURE. 149 



Annual Application to All Plots. 



Rate per Acre (Pounds). 

 High-grade sulfate of potash, i ........ 300 



Nitrate of soda, ^ .......... . 364 



Sulfate of ammonia, ........... 100 



Hoof meal ' (to all no-phosphate and mineral phosphate plots) , ^ . . 102 



The various forms of bone meal all contain organic nitrogen; the 

 steamed bone usually most. To equahze conditions hoof meal is applied 

 to each in such quantities as are required to bring the total organic nitro- 

 gen to the same amount as is furnished by the hoof meal on the other 

 plots. 



Plant-food Elements applied. 

 In the materials used the annual apphcation of plant-food elements has 

 varied somewhat with slightly varying composition of materials. One 

 important change has been made, viz., a 50 per cent, increase in the nitrate 

 nitrogen and in the actual potash in 1901. The annual apphcation per 

 plot has been substantially constant since that date, as follows : — 



Plant Food applied Annually {Pounds). 



Per Acre. 



Nitrogen, 

 Potash, 

 Phosphoric acid. 



91.2 

 152.0 

 96.0 



General Treatment. 



The entire field received an apphcation of hydrated hme at the rate 

 of one ton per acre in 1898, and again in 1914. This was spread upon the 

 plowed land in early spring and harrowed in. 



The stock of organic matter in the soil has been maintained by turning 

 under heavy crops, as follows: winter rye in 1901, buckwheat in 1912 

 and rye in 1913; and by introducing grasses and clovers, 1905 to 1907, 

 and turning under a heavy growth of grass before late cabbage in 1908. 



All fertihzers have been apphed broadcast in early spring, and, except 

 when the land was in grass, on the plowed surface and disked in. 



I For the first two years potash-magnesia sulfate, 400 pounds; in 1899, high-grade sulfate, 400 

 pounds; in 1901, potash-magnesia sulfate, 400 pounds. 

 - For the first four years 250 pounds. 



3 Tobacco dust was used by accident in place of hoof meal in 1911. 

 * To all bone-meal plots an amount to make total organic nitrogen equal. 



