1891.] PUBLIC DOCUMENT — No. 33. 149 



VI. Field Experiments to ascertain the Effect of 

 Different Combinations of Nitrogen, Nitrate 

 of Soda, Sulphate of Ammonia and Organic- 

 nitrogen-containing Compounds, Blood, under 

 Otherwise Corresponding Circumstances, on 

 Oats. 1890. (Field A.) 



The area occupied by this experiment is the same which 

 has served during four preceding years in succession — 1884 

 to 1888 — for the purpose of ascertaining the extent of the 

 inherent natural resources of potash. The results obtained 

 in that connection, which are described in our third, fourth, 

 fifth and sixth annual reports, left no doubt about the fact 

 that our farm land had been in an exceptional degree 

 impoverished in potash, in consequence of a too close 

 rotation of grass and corn. 



The field record of each of the ten plats, one-tenth of an 

 acre in size, extended over a period of more than six years, 

 as far as modes of cultivation and of manuring are con- 

 cerned. Some plats had received during that period a supply 

 of nitrogen for manurial purposes in but one and the same 

 specified form, while others had received none in any form. 

 This condition of the various plats was turned to proper 

 account in our new plans. 



1889. — Several plats which for five preceding years did 

 not receive any nitrogen compound for manurial purposes, 

 were retained in that state to study the effect of an entire 

 exclusion of nitrogen-containing manurial substances on the 

 crop under cultivation ; while the remaining ones received, 

 as before, a definite amount of nitrogen in the same form in 

 which they had received it in preceding years ; namely, 

 either as sodium nitrate or as ammonium sulphate, or as 

 organic nitrogenous matter in form of dried blood. A 

 corresponding amount of available nitrogen was applied 

 in all these cases. 



Aside from the difference regarding the nitrogen supply, 

 all plats were treated alike. They each received, without 

 an exception, a corresponding amount of available phos- 



