AVAILABILITY OF THE NITROGEN IN PACIFIC COAST 



KELPS 



By Guy R. Stewart, 

 Assistant Chemist, Agricultural Experiment Station of the University of California 



PURPOSE OF THE STUDY 



One of the first problems to be solved in the study of the fertilizing 

 value of the three major kelps of the Pacific coast, Macrocystis pyrifera, 

 Nereocystis luetkeana, and Pelagophycus porta, is the form in which 

 these plants can most economically and completely be utilized. The 

 difficulties inherent in any plan for manufacturing pure potash salts 

 as their sole product have already been pointed out by J. S. Burd (5)/ 

 of the California Agricultural Experiment Station. It has also been shown 

 in the same publication that the most feasible plan of manufacture 

 so far suggested is to dry and grind the kelp and to use it either alone 

 or preferably in combination with other ingredients as the basis for a 

 mixed fertilizer. The advantages of such a method of operation are at 

 once obvious. The low cost of operation and the probable complete 

 utilization of the plant food present are among the most evident. In 

 the latter connection, however, it at once becomes very pertinent to 

 inquire what will be the probable fate of the organic matter of the 

 kelp when added to the soil. 



Will it readily decompose and aid in the formation of humus? Will 

 its nitrogen and phosphoric acid become freely available for the crops 

 upon which it is used ? 



In addition, it will be very desirable to know what effect not only 

 the organic matter of the kelp but also its salts will have upon the 

 biological, chemical, and physical processes of the soil and also upon 

 the plants growing therein. The laboratory studies taken up in this 

 paper are intended to show the availability of the organic matter of the 

 kelps studied and also to give some insight into the effect of the salts 

 present in them upon the biological activities of the soil. 



The study of the changes taking place in organic matter when added 

 to the soil is of the most absorbing interest to modern investigators. 

 It has been the subject of many excellent researches during recent years, 

 though earlier work dates back to the time of Boussingault (2) in 1834. 

 At present the most satisfactory procedure for studying this problem 

 is undoubtedly the so-called beaker method of soil bacteriology, which 

 measures the availability of a material by the readiness with which 

 it will ammonify and nitrify when a small portion is added to a definite 

 quantity of soil. This method is now so well known that it hardly 



' Reference is made by number to "Literature cited," pp. 37-38. 



Journal of Agricultural Research, Vol. IV, No. i 



Dept. of Agriculture, Washington, D. C. Apr. 15, 1915 



Cal. — 

 (21) 



