1901.] PUBLIC DOCUMENT — No. 33. 93 



fertilizer, for various legumes, and includes forty plots ; 

 while fifteen plots in another locality have been used in a 

 soil test with grass as the crop. 



Most of the problems upon which wo hope to obtain light 

 by means of these experiments have engaged our attention 

 for a number of years. As might naturally l)e expected, the 

 results are somewhat affected by season, as well as by numer- 

 ous other causes which are not fully under control. Results 

 in some cases have varied to some extent from year to year, 

 and such variation nuist always be looked for in experiments 

 of this character. This variation, of course, renders inter- 

 pretation of the results a matter of much difficulty. iNIorc- 

 over, from the very nature of the questions engaging our 

 attention, it is necessary that the work should continue over 

 a considerable series of years before conclusions of general 

 interest and importance can be drawn. It does not, there- 

 fore, seem best to publish in full the details concerning any 

 considerable number of these experiments. Attention, how- 

 ever, will be called to some of the conclusions which it is 

 believed are fully warranted by the results, not of the past 

 year alone, but of a continuous line of investigations touch- 

 ing these points, many of which have continued for ten or 

 more years. 



I. — The Relative Value of Manures furnishing 



Nitrogen. 

 The experiments on wliich the conclusions now to l)e 

 stated are based have been carried out on Field A, and a 

 detailed description of the plan of experiment followed will 

 be found in our twelfth annual report. These exj^eriments 

 were begun in 1890, and the crops grown have been oats, 

 rye, soy beans, oats, soy beans, oats, soy l)eans, oats, oats, 

 clover and potatoes. As the result of these experiments, 

 we have found, taking into account all experiments from the 

 beginning of the work up to date, that the various manures 

 supplying nitrogen rank in the following order : nitrate of 

 soda, barnyard manure, sulfate of ammonia and dried blood. 

 If we allow numbers to express the relative efficiency of 

 these materials, their standing is as follows : nitrate of soda, 



