EXPERIMENTS WITH NITROGEN FERTILIZERS 7 



effect. In 1917, because of war conditions, the quantity of potash was reduced 

 40 per cent to 75 pounds per acre and the reduction was maintained until the 

 close of this study. 



Fertilizer Plan for Thirty Years 

 1889-1918 



Plot 0. — 800 lbs. manure, 32 lbs. sulfate of potash-magnesia, 18 lbs. dissolved boneblack. 



Plot 1. — 29 lbs. sodium nitrate, 25 lbs. muriate of potash, 50 lbs. dissolved boneblack. 



Plot 2. — 29 lbs. sodium nitrate, 48.5 lbs. sulfate of potash-magnesia, 50 lbs. dissolved boneblack. 



Plot 3. — 43 lbs. dried blood, 25 lbs. muriate of potash, 50 lbs. dissolved boneblack. 



Plot 4. — No nitrogen, 48.5 lbs. sulfate of potash-magnesia, 50 lbs. dissolved boneblack. 



Plot 5. — 22.5 lbs. ammonium sulfate, 48.5 lbs. sulfate of potash-magnesia, 50 lbs. dissolved bone- 

 black. 



Plot 6. — 22.5 lbs. ammonium sulfate, 25 lbs. muriate of potash, 50 lbs. dissolved boneblack. 



Plot 7. — No nitrogen, 25 lbs. muriate of potash, 50 lbs. dissolved boneblack. 



Plot 8. — 22.5 lbs. ammonium sulfate, 25 lbs. muriate of potash, 50 lbs. dissolved boneblack. 



Plot 9. — No nitrogen, 25 lbs. muriate of potash, 50 lbs. dissolved boneblack. 



Plot 10. — 43 lbs. dried blood, 48.5 lbs. sulfate of potash-magnesia, 50 lbs. dissolved boneblack. 



The arrangement of plots for the comparison of the fertilizers was influenced 

 by the treatment they had received in the previous period, and at the outset 

 the diiTerent plots were not as nearly uniform in their fertility as they apparently 

 were in 1883. 



Plot had been omitted from the experiment after 1884 because it showed 

 the residual effects of a manure pile which had been upon its surface at some 

 previous period. During this omission from the records it had probably been 

 planted with corn without fertilizer. It was restored to the experiment in 1889 

 and was fertilized with stable manure supplemented by boneblack and sulfates 

 of potash and magnesia. The amount of manure, 800 pounds, was calculated 

 from the average composition determined by numerous analyses and contained 

 an amount of nitrogen equal to that in the chemical fertilizers used. The supple- 

 mentary phosphoric acid and potash were necessary to equalize Plot with the 

 other plots. This plot was the only representation of this treatment and must 

 stand on one annual result. 



Plots 1 and 2 were selected for nitrate of soda because they had each received 

 that fertilizer at one time or another in the previous years. They adjoined and 

 were frequently fairly close together in yields. In 13 j^ears out of 33, their in- 

 dividual yields were within 1 per cent or less of their average. Plot 1 definitely 

 excelled Plot 2 in 14 harvests, while the latter excelled in 6. 



Plot 3, which received dried blood in the new plan, had also been dressed 

 repeatedly with it alone in the previous years. It was paired with Plot 10 at the 

 other end of the field. In the subsequent years, Plot 10 excelled Plot 3 in 15 

 harvests, while it was excelled by the latter 13 times. In five seasons, their 

 yields were so nearly alike that they may be considered as equal. 



