EXPERIMENTS WITH NITROGEN FERTILIZERS 



17 



Japanese millet was seeded in 1913 and cut for hay. The Hming of one-half 

 of each plot brought the ammonia plots to the front in yield, with organic nitro- 

 gen a good second. This kind of millet was grown in 1916 and was matured and 

 separated into seed and straw. The conditions were somewhat unlike those of 

 1913, when the millet followed two successive crops of corn. This year, the millet 

 had been preceded in 1915 by an exceptionally good clover crop, the sod of which 

 had been plowed under and on which potatoes had been planted before sowing 

 the millet. Defective seed caused a very uneven stand of potatoes, which were 

 plowed under and the millet substituted. 



Estimation of the efftciency of the different nitrogen fertilizers was puzzling. 

 Manure produced the highest yield of seed, while ammonia plots 6 and 8 bore 

 the smallest quantity. But total crop of seed and straw were practically equal. 

 Nitrate plots and organic nitrogen plots bore a similar relation to one another. 

 Plots without nitrogen were nearly as good in yield as those with nitrogen. 

 There may be noted in this crop the influence of the previous clover crop on the 

 nitrogen supply by the narrow gap between the plots without nitrogen and 

 those with it. 



Table 7 — Yield of Miscellaneous Crops 



(Pounds per plot.) 



*Lime applied. 



AN ECONOMIC VIEW OF THE EXPERIMENT 



A fertilizer experiment, of the kind on Field A, is made to ascertain the effects 

 of definite forms of fertilizers from which may be deduced plans for cropping 

 and manuring that will be economical. 



Did the crops grown on Field A use all the fertilizer that was applied each 

 year? The question can be partially answered by calculating the amounts of 

 fertility removed year by year in the harvested crops. Some of the crops grown 

 on these plots were analyzed and numerous analyses have been made of the 

 same kinds of crops grown on other fields of the experiment station. The data 

 have been used to calculate the amounts of nitrogen, phosphoric acid, and potash 

 contained in the crops during the years from 1889 to 1921, including 33 harvests. 



