Chemical Properties, Initial Microbial Populations And Survival Of Rhizobia In Peat, Vermiculite And Filtermud.

Abstract

Carrier materials are an important component of legume inoculants, especially in protecting the rhizobia. Selected physical and chemical properties, initial microbial populations (bacteria, actinomycetes and fungi) and survival of rhizobia introduced to peat and vermiculite as well as the Muhoroni filter mud [filter cake], which has long been used as a carrier for legume inoculants in Kenya, were measured. Peat and vermiculite originate from Ondiri and Kajiado respectively. Both sources are readily accessible from Nairobi, the location of the MIRCEN legume inoculant production facility. Peat was acidic while filter mud and vermiculite were near neutral. filter mud and peat had higher carbon contents. Vermiculite had much lower N content than the other two carriers. Original microbial populations in peat and filter mud were approximately 100-fold greater than in vermiculite. Peat and filter mud supported rhizobial densities of ~108 g-1 for six months, the duration of the experiment. The results indicate that Ondiri peat is a suitable carrier for legume inoculant production having properties which compare favourably with filter mud.