June IS, 191S Antagonism between Anions as Affecting Barley 211 



that, at least so far as some seasons are concerned, small quantities of 

 gypsum are as efficient for the purpose as larger quantities, if not more so. 

 Indeed, this would seem to reply to one of the questions above raised as 

 to the role of valence of ions in antagonism. It appears that small 

 quantities of calcium are as efficacious in antagonism to other ions as 

 large quantities of sodium or other univalent ions — or even more so. 



GENERAL DISCUSSION OF THE EXPERIMENTS 



Several questions arise in connection with the discussion of the fore- 

 going experiments which deserve brief attention here. 



GRAIN YIELDS AND ROOT PRODUCTION AS RELATED TO ANTAGONISM 



Thinking that it might be possible to correlate grain or straw yields 

 with antagonism between ions or with the lack thereof, we proceeded to 

 determine separately from the total weight of the tops of the barley 

 plants the weight of the grain produced. No regularity in the produc- 

 tion of grain with respect to soil treatment was found. At times the 

 treatment which yielded the largest amount of dry matter would also 

 be found to give the highest grain yields, but very frequently no such 

 relation could be established. If anything general could be stated with 

 reference to the grain yields of the barley plants, it would be that grain 

 production was nearly uniform throughout the series in any given season. 

 No significance can be found, therefore, to judge from our figures, in the 

 grain yields as criteria of absence or presence of antagonism. 



The case is not similar with respect to root production. No matter 

 how marked antagonism may be, as judged by the production of total 

 dry matter, root development from the absolute standpoint is always 

 markedly depressed in the presence of salts in the soil. To be sure, the 

 root production is often improved when total yields are increased, but 

 never in the same proportion, and it will be noted throughout in the 

 tables that the root production is always largest in the control pots. 

 Moreover, in the case of the root growth as in that of grain yield, we find 

 great irregularity, for much of which we are unable to account. 



COMPARISON OF OUR RESULTS WITH THOSE OF OTHER INVESTIGATORS 



As Stated above, the only other results, so far as we are aware, which 

 have been obtained in antagonism work with anions are those of Miyake 

 (10), which were published after our preliminary statement had appeared. 

 Even Miyake's work, however, gives no results of the antagonism between 

 anions as noted in soil cultures, for all his experiments of this kind were 

 carried out in solutions. Nevertheless, the general nature of the work 

 of the Japanese investigator may here be mentioned for comparison with 

 ours and in confirmation of the latter. Miyake found that for the rice 

 plant (Oryza sativa) grown in culture solutions antagonism is apparent 



