842 EXPERIMENT STATION RECORD. 



ill weight of plants. The same author ' has supplemented his earlier 

 work by his investigations on the influence of different proportions of 

 fertilizing elements upon increase in M^eight. lie found that unless 

 the total amount of fertilizing materials was excessive, an excess of 

 one constituent over another was not detrimental, since part of the 

 excess was not used by the plant. Part of the constituent is used to 

 increase the yield of the crop, but not as much as would have been 

 taken up had it been present in proper proportion. Yields of plants 

 may be increased by increasing the amount of complete fertilizers 

 applied up to a certain limit. This limit, however, is raiher high, it 

 being x>ossible to increase twenty times the amount of fertilizer com- 

 monly used. The increase in yield is at first nearly proportional to 

 the increased amount of fertilizer applied, but gradually becomes less 

 and less, until it disappears and the fertilizer becomes injurious. Plants 

 in poor soil are better adapted to the utilization of small quantities 

 of fertilizers than large amounts. A natural soil gives up its fertilizing 

 materials very slowly, and so its reserve of fertility may be retained for 

 a long time. 



The conclusions of Eaulin's work explain some facts often observed 

 in practice, notably that good results on poor soils follow the applica- 

 tion of small quantities of chemical fertilizers. 



The question of the nitrogen nutrition of plants has received much 

 attention. Miintz^ hasstudiedthe extent to which atmospheric ammonia 

 aids in the nutrition of plants. Schlossing in 1874 demonstrated that 

 gaseous ammonia may be absorbed by leaves. The recent work of 

 Miintz shows that astriugent substances in the ijlant, acid salts, and 

 free acids are able to fix ammonia. The amount of atmospheric ammo- 

 nia taken up annually i)er hectare is about 10 kg. for maize and arti- 

 chokes and 2 to 3 kg. for oats, sugar beets, and grai)evines and an equal 

 amount of nitrogen is carried down in the rain water, but this does not 

 indicate that nitrogenous fertilizers may be disi)ensed with. Ammonia 

 once fixed is not liberated, but enters into the i)rocesses of synthesis 

 under the influence of light. This phenomenon is associated with 

 resi)iration and assimilation. 



The ammonia of the air does not play a very important role, but this 

 is not true of the free nitrogen of the air. Continuing the researches 

 of Berthelot, Hellriegel, Wilfarth, Winogradsky, Deherain, and Schloss- 

 ing and Laurent, R. Bouilhac ' has studied the fixation of atmospheric 

 nitrogen by bacteria and algte. His experiments show that Schi.zothrix 

 lardacea and Ulothrix flaccida are unable to grow in nutrient solutions 

 lacking nitrogen, even when associated with various soil bacteria. 

 On the other hand, Xostoc punctifonnc is able to fix free nitrogen. 

 This plant compares with the Leguminoste in being especially rich in 



'Ann. Sci. Agron., ser. 2, auu. 2, 1 (1896), p. 404. 



"Ibid., p. 161. 



3Compt. Rend., 123 (1896), p. 828. 



