1917. 



PUBLIC DOCUMENT — No. 31. 



49 a 



For the last six years certain areas of each plot have been 

 continuously in onions. The following table shows the yields 

 obtained each yeai, the average for the five years previous to 

 1916, and the yield for this season. These figures represent the 

 total yields of the different plots, both limed and unlimed 

 areas. 



Onions, Yields Bushels per Acre {Whole Plot). 



The figures show that for the onion crop, with one excep- 

 tion, no benefit is derived from the addition of chemicals to 

 manure; that the best source of nitrogen is nitrate of soda, 

 and the source least beneficial to the crop is sulfate of 

 ammonia; and that there is very little difference between the 

 two sources of potash. 



Considering the fact that no potash was applied this year, it 

 would seem that on land in a high state of cultivation, which 

 has received liberal annual applications of fertilizers contain- 

 ing potash, a good crop might be expected for at least one year 

 without the use of any potash. 



Comparison of Different Phosphates. 

 This experiment was begun in 1897, and has for its object a 

 comparison of ten different materials that may be used as 

 sources of ' phosphoric acid. The data for the first eighteen 

 years of the experiment were published in Experiment Station 

 Bulletin No. 162. The crop this year was field corn, and the 

 results obtained, are shown in the following table: — 



