Apr. 15. 1915 Availability of the Nitrogen in Kelps 29 



The analytical tables furnish some interesting results. It is at once 

 evident that the fresh Macrocystis, whether leached or unleached, is 

 readily decomposed by practically all of the four soils. It is also appar- 

 ent that the leaching, which has removed a considerable portion of the 

 soluble salts present, has not increased the rate at which the nitrogen 

 is changed to more available forms. It was originally planned to incu- 

 bate all of this series for 7 days. Upon analyzing the cultures with 

 leached kelp, however, it was found that the decomposition had not 

 been so rapid as anticipated, and it was supposed that the unleached 

 samples would be slower still. They were therefore incubated for 11 

 days. The result proves that decomposition had been going on in this 

 portion of the set as rapidly as in the leached. The removal of the 

 salts from Macrocystis would not, therefore, be advantageous to in- 

 crease its rate of decomposition. It is also interesting to note that 

 nitrification has taken place with the fresh kelp in all of the soils except 

 the sandy, a type which is frequently somewhat slow in this respect. 



With the dry Macrocystis in this series both the leached and un- 

 leached gave practically a negative result. It was to be expected that 

 there would be some disparity in the availability of the fresh and dried 

 material. A green-manuring crop which is dried before it is turned 

 under the soil differs somewhat similarly from the same crop turned 

 under in a green condition, the fresh legumes decomposing more readily 

 than the dried. The difference between the fresh and the dry Macrocystis 

 is, however, very great. We have no proof as yet of the final availa- 

 bility of the dry Macrocystis. To demonstrate this, we require a posi- 

 tive gain of both ammonia and nitrates. It is of decided importance in 

 our study to have found that the fresh Macrocystis will decompose with 

 any average soil. 



SERIES III.— THE EFFECT OF EARGE AND SMALL AMOUNTS OF DRIED 

 MACROCYSTIS AND NEREOCYSTIS ON THE AMMONIFICATION AND 

 NITRIFICATION OF DRIED BLOOD 



The results so far obtained have left several points undecided. It 

 has been indicated that oven-dry Macrocj^stis decomposes quite slowly, 

 while Nereocystis at least ammonifies readily. Fresh Macrocystis both 

 ammonifies and nitrifies. It now becomes desirable to know how long 

 a period will elapse before dr)?^ Macrocystis in small or large quantities 

 will decompose. Will dry Nereocystis in moderate amounts nitrify, as 

 well as ammonify ? And as kelp will probably be used with other or- 

 ganic fertilizers, how will materials like blood or tankage behave when 

 the salts of kelp are also present ? 



The following series was therefore planned : Air-dried Macrocystis pyri- 

 fera and oven-dried Nereocystis luetkeana were each added to duplicate 

 sets of tumblers. The amounts used furnished 10, 50, and 100 mg. of 

 nitrogen. To another set of tumblers with the same three quantities 

 of kelp, dried blood to furnish 10 mg. of nitrogen was added. In like 



