210 EXPERIMENT STATION RECORD. 



iicial fertilizer. Vegetation experiments enable the experimenter to 

 eliminate the outside disturbing influences and conditions, and to place 

 the plants under conditions which bring - out the efficiency of the ferti- 

 lizer or ingredient which is being tested. Every new fertilizing mate- 

 rial which makes its appearance can now be tested as to its value in 

 vegetation experiments. The bearing of these vegetation experiments 

 can be illustrated by the case of Thomas slag, which is at present used 

 more extensively in Germany than any other phosphate, much to the 

 advantage of agricultural production. The rapid introduction and 

 widespread use of this material is due to the results obtained with it by 

 Professor Wagner in vegetation experiments. Field experiments could 

 never have brought about such a rapid extension in the use of Thomas 

 slag. 



It should not be understood, however, that the vegetation experiments 

 have rendered field experiments unnecessary. On the contrary, to 

 apply the results of vegetation experiments to actual practice on a large 

 scale field experiments will always remain indispensable; but the 

 fundamental scientific questions cannot be answered by field experi- 

 ments. For this jmrpose vegetation experiments must always be relied 

 upon. 



The vegetation experiment is also coming into extensive use by the 

 German experiment stations for another purpose; namely, for studying 

 the fertilizer requirements of soils. Chemical analysis, as explained 

 above, is by no means suited to determine with certainty the fertilizer 

 requirements of an agricultural soil. This is best accomplished by 

 vegetation experiments, i. c. through the analysis of the soil by the 

 plant. 



This method of determining the fertilizer requirements of the soil is 

 extensively used at the Halle station for the benefit of the farmers of 

 the Province of Saxony. By this means the farmers learn on which 

 soils they can omit certain fertilizers and on which they must apply the 

 same in large amounts. 



Finally the agricultural experiment stations must attack the questions 

 of animal nutrition in similar manner. Heretofore the digestibility of 

 the constituents of the various feeding stuffs have been studied with 

 profitable results, and on the basis of these investigations practical 

 tables showing the digestibility of feeding stuffs 1 have been prepared. 

 On the basis of the feeding experiments which have been made, feed- 

 ing rations for animals, containing the proper amounts of digestible 

 nutrients for the most advantageous production, may be compounded 

 from different feeding studs. Much remains to be done, however, in 

 solving the more intricate problems relative to animal nutrition, and 

 for this respiration experiments arc important. The natural laws of 

 the nutrition of Herbivora are, in spite of much research, not fully 

 understood, and Henneberg's classic investigations on this subject 



1 See the extensive compilation of Dietrich and Konk 



