During this period, he worked on a number of topics, among them iron bacteria, nitrifying bacteria, nitrogen fixation by Azotobacter, cellulose-decomposing bacteria, and culture methods for soil microorganisms.
I denne periode arbejdede han på en række emner, heriblandt jernbakterier, nitrificerende bakterier, kvælstoffiksering af Azotobacter, cellulose-nedbrydende bakterier og kultiveringsmetoder for mikroorganismer i jord.