Apr. 32, 1918 Biological A ctivities and Concentration of Soil Solution 219 



which do not depress ammonification. It is rather striking in this 

 series, however, that when an increase in osmotic pressure occurs the 

 ammonia produced drops to that of the untreated soil. 



The data with clay loam are exceedingly interesting. There appears 

 at first to be a slight depression of ammonia production, the depression 

 increasing until with 0.016 per cent of calcium chlorid it reaches almost 

 9 mgm. of nitrogen, or 19 per cent, considering the production in the 

 untreated soil as 100 per cent. With 0.032 per cent of salt ammonifica- 

 tion returns to normal and remains so until 0.300 per cent of salt is 

 present, when it is slightly depressed again and remains so with but 

 small increases of depression throughout the series. In no other concen- 

 tration in the series, however, is the ammonia production reduced to 

 quite so low a point as with 0.008 and 0.016 per cent of the salt. 



The osmotic pressure of the soil solution shows a sharp increase with 

 addition of 0.064 per cent of calcium chlorid, and thereafter there is a 

 further increase with each addition of the salt. It is noteworthy, how- 

 ever, that ammonification returns to normal before there is any appreci- 

 able increase in the concentration of the soil solution. 



Table IV. 



■Ammonification of dried blood in sandy loam, and clay loam, with varying 

 percentages of potassium, chlorid 



Salt in air-dry soil. 



Sandy loam. 



Nitrogen 

 produced. 



Depression 



of freezing 



point. 



Osmotic 

 pressure. 



Clay loam. 



Nitrogen 

 produced. 



Depression 



of freezing 



point. 



Osmotic 

 pressure. 



Per cent. 



o. 000 



.001 



. 002 



.008 



. 016 



•032 



.064 



. 100 



, 200 



•300 



. 400 



•500 



. 600 



. 700 



Mgm. 

 75-70 

 71-63 

 73-87 

 73-45 

 69-53 

 67-99 

 60.43 

 57.20 

 54.26 

 63-65 

 57.06 



44-03 

 33-95 



'C. 



0. 285 

 .280 



•273 

 .298 



•325 

 •373 

 .440 



•538 

 •858 



1. 118 

 1. 410 

 1-723 



Atmos- 

 pheres. 



3-435 

 3-375 

 3.291 



Mgm. 

 52. 10 

 50.08 



o. 276 

 . 260 



592 

 917 



495 

 302 

 482 

 10. 336 

 10. 768 

 16. 960 

 20. 716 



45-85 

 49. 08 

 48. 38 

 50.48 

 45-71 



276 



305 

 302 



336 

 421 



38.29 



765 



38.43 



1.093 



35-07 



1-455 



A tmos- 

 pheres. 



3- 327 

 3- 134 



3-327 

 3.676 

 3.640 

 4.050 

 5-074 



9.214 



13- 156 



17.500 



The data in Table IV show a well-defined decrease in ammonification 

 when 0.064 per cent of potassium chlorid is added to sandy loam; how- 

 ever, a decided increase in the osmotic pressure of the soil solution is 

 noticeable when only one-fourth of this amount of the salt is added. 

 This agrees closely with the results obtained when calcium chlorid and 

 calcium nitrate are applied to this soil. 



