Apr. 15. I9IS Availability of the Nitrogen in Kelps 25 



becomes more balanced in its character. He has shown that the prin- 

 ciples of antagonism previously established by Loeb (13, 14) and Oster- 

 hout (16, 17) for animals and plants also hold in general for soil bacteria. 



Considering now the results obtained in Series I, it will be observed 

 that the first ammonia determinations were made at the end of 9 days' 

 incubation. Other duplicate sets were analyzed at periods of 11, 15, 

 19, 48, and 102 days. Even at the end of 9 days it will be seen that 

 very striking differences exist. As was to be expected, the dried blood 

 ammonifies most readily. Next in rate of conversion is the cottonseed 

 meal, while Nereocystis luetkeana is not very far behind this. Pelago- 

 phycus porra is distinctly slower, while Macrocystis pyrijera shows only 

 a trace converted. 



Still considering the ammonification, the same relationship holds with 

 the kelps throughout the whole series. After 15 days the major portion 

 of the nitrogen, which was changed to ammonia with the blood and the 

 cottonseed meal, has been converted over into nitrates. It must be 

 pointed out in the discussion of the results of this first series that the 

 amounts of kelp added were quite excessive. The only reason for employ- 

 ing such quantities even in a laboratory study was that it furnished an 

 amount of nitrogen which would give a very satisfactory analytical figure 

 should conversion readily take place. It had been supposed also that all 

 the kelps were probably very available and would decompose readily, so 

 the large quantities used were intended to test this beHef under extreme 

 conditions. 



Taking this series as a whole, it will be seen that even with the 

 large content of soluble salts furnished by the kelp, ammonification took 

 place with surprising readiness in the case of Nereocystis and Pelagophy- 

 cus, while with Macrocystis it was only after 48 days had elapsed that 

 definite small amounts were converted to ammonia. Nitrification, how- 

 ever, in the case of all the kelps was almost entirely inhibited; in fact, 

 even the amounts originally present in the soil did not remain at the end 

 of the period in the form of nitrates. At the close of the final period, 102 

 days, duplicate sets of tumblers were mixed and the total amount of 

 nitrogen determined by the modified Kjeldahl method to include the 

 nitrogen of nitrates. 



Recovered. Added. 

 Material. Mg. Mg. 



Macrocystis pyrifera < ^° ' 5 U 



Nereocystis licetkeana < ^ ,5- 7 L 



Pelagopkycus porra < ^ ^'^^ ^122 



Dried blood |'°°- 4i32 



( 92. 2j "^ 



Cottonseed meal 124. 7 128 



There has apparently been a slight denitrifiation in the case of the 

 dried blood, but with the other materials the amount recovered is sub- 

 stantially the same as that which had been added. 

 79827°— 15 3 



rio7 

 k66 



