H. B. Hutchinson 109 



Bacteria Nitrogen as ammonia and nitrate 

 (millions per grm. of soil) (pts per million of soil) 



At After After After At After After After 



Soil I start 23 days 48 days 114 days start 23 days 48 days 114 days 



Soil alone 12-9 10-3 210 — 17 30 28 30 



SoU+sugar 12-9 470 510 — 17 13 13 20 



Bacteria Nitrogen as ammonia and nitrate 



(millions per grm. of soil) (pts per miUion of soil) 



At After After After After At After After After After 

 Soil II start 6 days 62 days 101 days 215 days start 6 days 62 days 101 days 215 days 



Soil alone 8-2 13 2 6-9 10-6 12-4 55 51 71 85 98 



Soil + sugar 8-2 129 2 96-6 32-3 25-9 55 5 24 37 71 



The addition of hay dust to the soil has a like effect. Two soils were 

 tested, the first being an untreated soil, and the second, a toluened soil 

 which had been stored in the laboratory for some months prior to treat- 

 ment with hay dust. The results are summarised below: 



It cannot be assumed from these data, however, that the soil actually 

 loses nitrogen to the extent represented by the disappearance of nitrates 

 after treatment. Many organisms are known to have the capacity of 

 assimilating nitrogen in the form of nitrate and of elaborating it into 

 protein; even under the conditions most favourable for true denitrifica- 

 tion (that is, the Hberation of gaseous nitrogen) upwards of 25-30 per 

 cent, of the total nitric nitrogen can frequently be recovered as bacterial 

 protein. Nitrate disappearance does not therefore provide a true index 

 of actual soil losses, and it is in fact reasonable to suppose that under 

 conditions where the soil is otherwise likelv to lose the greater part of its 

 soluble nitrogen compounds by excessive leaching, such a retention of 

 nitrogen in the organic form may be more or less of an asset. 



Finally, sufficient evidence has been advanced to establish a close 

 relation between the results obtained by the addition of hay dust and 

 sugar to laboratory and field soils, and those obtained by Wagner (31), 

 Maercker(32) and others when simultaneous applications of nitrate of soda 

 and farmyard manure, straw, etc., were made to the soil. Although the 

 conditions which prevailed in their experiments were decidedly abnormal 



