ANTAGONISM BETWEEN ANIONS 803 



0.5% of the dry weight of the soil, nitrification is only slightly 

 below the normal. 



Considering Table IXb the reciprocal of I\^\ in which a con- 

 stant toxic quantity of Na2S04 namely 0.35% is employed we 

 find the following. When 0.35% Na2S04 is added alone, the nitri- 

 fying power of the soil is depressed by about 15%. "V\Tien how- 

 ever varying quantities of NaCl are added thereto ranging from 

 O.Oo^/c to 0.15% inclusive nitrification is gradually improved 

 as the amount of the latter salt is increased until at the last 

 named concentration nitrification is again brought back to the 

 normal. 



Table Va and its reciprocal, however, show what are probably 

 the most striking results owing to the acutely toxic nature of 

 NaoCOs. Considering each of the two tables separately we find 

 that an addition of 0.05% Na2C03 depresses nitrification to a 

 point approximately 75% below the normal. When however, 

 varying amounts of NajSOa are added with the Na2C03 nitri- 

 fication is gradually improved as the amount of Na2S04 is in- 

 creased until it reaches the very high concentration of 0.5%. 

 Even at that very high salt concentration nitrification is su- 

 perior to that of the normal soil and even an addition of 0.6% 

 Na2S04 to the 0.05% Na2C03 allows the latter to lower nitrifi- 

 cation only very slightly. It is difficult to conceive of anything 

 more striking than these data in support of the theory of antago- 

 nism between ions. 



In Table Vb the reciprocal of Table Va in which 0.35% Na2S04 

 is used as the constant toxic salt concentration we find that 

 0.35% Na2S04 alone as in some of the foregoing tables lowers 

 the nitrifying power of the normal soil by approximately 15%. 

 When, however, varying quantities of Na2C03 ranging from 

 0.01% to 0.05% inclusive are added to it nitrification is most 

 markedly stimulated and increased by about 40% in excess of the 

 normal soil. 



Considering briefly the last two reciprocal tables we find 

 again most striking evidence in support of antagonism between 

 anions. Thus, for example in Table VIa in which the constant 

 toxic salt Na2C03 is used again at a concentration of 0.05% of 



