Apr. IS. 19IS Availability of the Nitrogen in Kelps 27 



SERIES II.— COMPARATIVE AMMONIFICATION AND NITRIFICATION ON 

 FOUR TYPICAL SOILS OF FRESH AND DRIED MACROCYSTIS, COTTON- 

 SEED MEAL, AND DRIED BLOOD 



The results obtained in Series I clearly show the readiness with which 

 Nereocystis luetkcana and Pelagophycus porra are decomposed in the soil 

 with the formation of ammonia. With smaller concentrations of kelp, 

 this would probably be readily converted over to nitrates. These 

 varieties, however, are only of minor importance from a commercial 

 standpoint. As has been pointed out by J. S. Burd (5), the Macrocystis 

 is the only one which can be considered commercially important in 

 California. 



A second series of ammonification and nitrification studies was there- 

 fore started to further investigate the availability of Macrocystis pyrifera. 

 It was felt also that the composite analytical sample of Macrocystis 

 which was used in the first series had possibly been dried for a longer 

 time than would be the case if the kelp were handled commercially. 



In the second series, therefore, M. pyrifera, which, after having been 

 thoroughly sun-dried, contained 10.52 per cent of moisture, 0.80 per cent 

 of nitrogen, and 30.80 per cent of soluble salts, was employed. Fresh 

 kelp, just gathered from the ocean, was also obtained at Pacific Grove, 

 Cal., brought to Berkeley the same day, and placed in a refrigerator till 

 it was used the following morning. The fresh kelp contained 87.9 per 

 cent of moisture, 0.22 per cent of nitrogen, and 4.60 per cent of soluble 

 salts. These two fonns of kelp were again contrasted with dried blood 

 and cottonseed meal. In order to study the effect on a variety of soils, 

 four different types of fresh field soil were employed. The first was again 

 the clay adobe from the university campus. The next was a highly pro- 

 ductive alluvial loam from Hayward, Cal. A moderately productive clay 

 loam was also obtained from Hayward, and for the fourth a light sandy 

 soil from the vegetable-garden district of South San Francisco. 



The series was divided into two sets. In the first set both the fresh 

 and the dry Macrocystis were partially leached with distilled water. 

 Any such treatment of the fresh kelp would be impracticable on a large 

 scale. The thick colloidal solutions formed are extremely difficult to 

 pour or filter. A great deal of moisture was also retained by the kelp. 

 After leaching, the fresh sample contained 95.46 per cent of moisture, 

 0.09 per cent of nitrogen, and 1.46 per cent of soluble salts. The dried 

 and ground Macrocystis was easily treated with about 15 c. c. of distilled 

 water. This removed a few milligrams of nitrogen and two-thirds of 

 the soluble salts. The tumblers of this set were incubated for 7 days. 



In the other set the kelp was added to the soil without leaching, and 

 the period of incubation was 1 1 days. The fresh kelp used in both sets 

 was ground by passing it through a food chopper. The dry Macrocystis 

 was ground, as in Series I, and the same analytical procedure was fol- 

 lowed. (See Table II.) 



