Bacillus and azotobacter counts in solid biofertilizer with different concentration of zeolite and liquid inoculant

Abstract

Bacillus and Azotobacter sp are Plant Growth Promoting Rhizobacteria widely used as biofertilizer. The success of commercial carrier-basedbiofertilizer is depend on formulation which dictate the shelf live and cell viability as well. A laboratory experiment was conducted to evaluate the population of Bacillus and Azotobacter in compost-based solid biofertilizer with several zeolite and liquid inoculant concentration. The experiment was conducted in completely randomized design which test the combintion treatment of three concentration of zeolite (0.1, 1 and 5%) and four concentration of initial liquid mixed inoculant (1, 5, 10 and 15%). All formulations were incubated at room temperature prior to count the Bacillus and Azotobacter population at day 7, 14, 21 and 28. The results verified that, the population of both bacteria in compost-based inoculant were higher than initial population. The zeolite and liquid inoculant concentration influenced Bacillus count at 7 days and Azotobacter count at 7 and 14 days Nonetheless the higher population of both bacterial species was in the compost-based biofertilizer contained 1% zeolite and 10% of liquid inoculant as well as 5% zeolite and 5% liquid inoculant. Both formulations maintain the Bacillus and Azotobacter population up to 12 and 10 log of cfu/g respectively.