Apr. 22, 191 



8 Biological Activities and Concentration of. Soil Solution 217 



per cent of the salt gave results practically identical with those of the 

 untreated soil; but with an addition of 0.064 P^^ cent a marked decrease 

 in ammonia production resulted. With a higher percentage of the salt 

 the results show irregularities due to experimental errors, but they also 

 show a general tendency to depress ammonification still further. When 

 0.7 per cent of the salt was added, a very great decrease resulted in the 

 amount of ammonia produced. 



A tendency to increase the osmotic pressure in the sandy-loam series is 

 noticeable with an addition of 0.016 per cent of the salt. This tendency, 

 however, is more pronounced at 0.064 per cent ; and thereafter the osmotic 

 pressure rises steadily with no irregularities. 



The results with clay loam show a small but persistent stimulation 

 of the ammonifying organisms until a concentration of 0.064 P^r cent 

 of the salt is reached, when the production of ammonia drops back to 

 practically that of the untreated soil. 



There is very little further decrease in the amount of ammonia pro- 

 duced with a greater application of the salt, except in the case of 0.500 

 per cent. Since, however, the production with 0.700 per cent rises to 

 practically that of the untreated soil, it seems probable that the reduc- 

 tion with 0.500 per cent of the salt is an experimental error. There is 

 no point, therefore, at which it can be said that a marked toxicity to 

 ammonification occurs. 



It is interesting to note that there is no marked increase in the osmotic 

 pressure of the soil solution until an addition of 0.300 per cent of the 

 salt has been made, which is somewhat more than the amount present 

 when ammonification was reduced to normal. 



Table II. — Amvwnificalion of dried blood in sandy loam and clay loam with varying 

 percentages of calcium nitrate 



Salt in air-dry soil. 



Per cent 



O. 000 



. 001 



. 002 



.008 



. 016 



•032 



. 064 



. 100 



. 200 



•300 



. 400 



• 500 



. 6CX5 



. 700 



Sandy loam. 



Nitrogen 

 produced. 



Mgm. 



Depression 



of freezing 



point. 



0. 285 

 .263 

 .280 



• 252 

 .277 

 •307 

 •364 

 •394 

 •523 

 .685 



• 790 

 ■930 



1. 060 



Osmotic 

 pressure. 



Almos- 

 pheres. 



3-435 



3- 170 



3-375 

 3-038 



3-339 

 3.700 



4-387 



4- 748 

 6. 302 

 8.251 

 9-514 



11. 20 



12. 76 

 13. 864 



Clay loam. 



Nitrogen 

 produced. 



Mgm. 

 52. 10 

 55-52 



55- 24 

 51.88 



49-92 

 55- 66 

 53-70 



48. 24 

 49-36 



47-54 



Depression 



of freezing 



point. 



276 



275 



285 



295 

 290 



330 



393 



568 



683 



873 



Osmotic 

 pressure. 



Atmos- 

 pheres. 



3-327 



3-435 

 3-546 

 3- 496 

 3-978 

 4-736 



6.843 



8. 227 



10. 516 



