Effectiveness of rhizobium trifolii populations associated with trifolium species in taranaki, new zealand

Abstract

Indigenous Rhizobium trifolii from 30 sites in Taranaki were evaluated for population size and effectiveness in nitrogen fixation with white clover. Sites were classified on the basis of stage of development/fertility status and Trifolium species present. Numbers of R. trifolii were high at all sites. The lowest count was 1.7 × 104 cells per g of soil, and 13% of the sites contained more than 106 cells per g of soil. Numbers tended to be higher at sites containing more than one Trifolium species and decreased with lower stage of development/fertility status. Regression analysis of soil and Rhizobium data showed significant correlations between effectiveness and calcium concentration, total exchangeable bases, percent base saturation, and altitude. The mean effectiveness of cultures isolated from resident white clovers was 77.9% compared with a standard effective strain. The mean site scores varied from 51 to 98%. No culture was totally ineffective on white clover. Some evidence was obtained that Huia and the field white clovers were not always nodulated by the same fraction of the total soil rhizobial population. © 1981 Taylor & Francis Group, LLC.