An investigation of 'Azotobacter' spp. population distribution in differently managed soils

Abstract

Nitrogen fixation is the biocatalytic conversion of gaseous nitrogen (N 2) to ammonium, and it is an exclusive role of nitrogen fixing prokaryotes. The enzymes responsible for the reaction are nitrogenases, whose activity are affected by environmental factors such as soil organic matter and oxygen content, which vary with different soil management practices. The distribution of Azotobacter spp. as a function of soil management and soil organic matter was investigated in a man modified Terra Rossa type soil subjected to different management practice. Contrary to what was expected, results indicated that number of Azotobacter spp were not highest where the soil organic matter was highest. Azotobacter number was high in the sites where tillage practice was high.