222 



Journal of Agricultural Research voi. xiii, no. 4 



Table VI. — Ammonification of dried blood in sand with varying percentages of 



potassium chlorid 



Salt in air-dry soil. 



Sand. 



NitroEcn 

 produced. 



Depression 



of freezing 



point. 



Osmotic 

 pressure. 



Per cent. 



o. 000 



. 001 



. 002 



. 004 



.008 



. 016 



•032 



. 064 



. 100 



. 200 



•300 



. 400 



. 500 



Algm. 

 32. 64 



33-34 

 31.80 

 32- 36 

 24- 73 

 29. 14 

 28. 44 

 23. 82 

 27.88 



16.53 



10. 09 



6. 44 



5-88 



°C. 



I- 157 

 I. 109 

 1. 120 

 1-137 



I. lOI 



1.086 

 I. 160 



1-587 

 1-837 

 2.746 



A tmos- 

 plieres. 



13-924 

 13- 348 

 13. 48 

 13. 684 

 13-372 

 13. 072 

 13.96 

 19. 084 

 22. 084 

 32. 962 



These results show ammonification proceeding normally when the os- 

 motic pressure of the soil solution is from 13 to 14 atmospheres. This is 

 twice the osmotic pressure in sandy loam when calcium nitrate depressed 

 ammonification and three times that when magnesium sulphate caused 

 a decrease in ammonia production. It seems justifiable from the data 

 presented to conclude that osmotic pressure is not the determining factor 

 in the reduction of ammonification by the salts used. 



One point should be mentioned in this connection. Neither in this 

 work nor in the results of other workers reviewed by the writer have the 

 total osmotic pressures of the soil solution been reported at the time the 

 ammonia determinations were made. It is possible that the pressure 

 due to the products of bacterial action plus that due to the salt added 

 may equal a constant. 



Table VII. — Effect of dried blood on the osmotic pressure of the soil solution 



Kind of soil. 



Sand 



Do 



Do 



Sandy loam 



Do 



Do 



Clay loam. . 



Do 



Do ... . 



Amount 

 of soil. 



Gm. 

 100 

 100 

 100 

 100 

 100 

 iIjO 

 100 

 100 

 100 



Amount of 

 dried blood. 



Gm. 



0. O 



1. O 



2. o 

 . O 



1. O 



2. O 



. o 



I. o 



Freezing- 

 point de- 

 pression. 



°C. 



I. 160 

 . 267 

 - 157 

 •135 

 . 190 

 .285 

 . 160 



-195 

 .276 



Osmotic 

 pressure. 



Aijnos' 

 pheres. 

 1.930 

 3.218 

 13. 924 

 1.518 

 2. 291 



3-435 

 1.930 



2-351 

 3- 327 



DiSerence 



in osmotic 



pressure 



due to 



dried blood. 



Atmos- 

 pheres. 



, I. 288 

 11.994 



•773 

 I. 917 



.421 



1-397 



