Apr. IS, 1915 Availability of the Nitrogen in Kelps 33 



The data obtained where dried blood alone was added do not call for 

 any special comment. The production of ammonia and nitrates, with 

 some minor variations, proceeds through each period. When Macro- 

 cystis and blood are present, the conditions are very different. The 

 blood is a very available material; the Macrocystis is slowly available. 

 It is therefore reasonable to suppose that the first gains of ammonia and 

 nitrates will be due to the blood. Later, , the Macrocystis may also 

 furnish a portion of the nitrogen gained. If at all times the percentage 

 of total gain is calculated as if it were due to the nitrogen of the blood, 

 it can readily be seen whether the total amount gained is greater or less 

 than that where the blood alone was present. This has accordingly been 

 done. If the kelp also furnishes a large part of the gain, the result will 

 evidently exceed 100 per cent and will clearly indicate this fact. It is 

 not claimed that this procedure is strictly accurate, but it will demon- 

 strate whether as much nitrogen is gained with blood and kelp as with 

 blood alone. 



With two weeks' incubation we find that this is not so. All quantities 

 of Macrocystis give a reduction in the total gain. Ten mg. of nitrogen 

 in kelp added to one hundred in blood show the smallest inhibitive 

 effect. At four weeks the results are practically the same. Eleven 

 weeks' incubation shows a distinct reduction of the inhibition; especially 

 is this so in regard to nitrification. At 15 weeks it is found that with 10 

 mg. of blood and with both 10 and 50 mg. of kelp inhibition has ceased and 

 there has been a gain from the kelp added. With the loo-mg. tumblers 

 of blood and Macrocystis nitrification is observed to have commenced. 

 The general evidence would appear to be that at first there undoubtedly 

 is an inhibitive effect from the Macrocystis. This inhibition is gradually 

 reduced as time goes on. 



The results from the two sets of tumblers with dried and ground 

 Nereocystis furnish a very striking contrast to those from the Macrocystis. 

 With the kelp alone there is a very ready and uniform conversion to both 

 ammonia and nitrates. It is only with the loo-mg. portions that a very 

 marked inhibition of nitrification has occurred. 



The total gain of ammonia and nitrates has again been calculated as 

 if it were all due to blood. The resulting percentages in a number of 

 cases show a greater gain than occurred where blood alone was added to 

 the soil. The difference is naturally assumed to be due to the Nereocvstis 

 present. This difference between the blood alone and blood plus Nereo- 

 cystis has been calculated as the percentage of Nereocystis nitrogen 

 gained. The data throughout show that the Nereocystis is a very avail- 

 able material. This corroborates the results obtained in Series I, which 

 showed that it readily ammonified. We have now proved in addition 

 that it also nitrifies rapidly. 



