Mass Production of Free-Living and Symbiotic Nitrogen-Fixing Biofertilizers and Comparative Efficacy Study of Different Carriers

Abstract

There is a high demand for food worldwide which has caused the increase in the use of chemical fertilizer to fulfill the global need for food. The use of chemical fertilizer has a negative impact on the environment which has exponentially raised the global interest in microbial fertilizer. This study focuses on the easy and costeffective

use of carrier material that can be used in the production of microbial fertilizer. For these symbiotic bacteria (Rhizobium) and non-symbiotic bacteria (Azotobacter) were used as microorganisms and charcoal, rice husk, and farmyard manure as carrier material were used. Rhizobium species and Azotobacter species were isolated from pea plant root nodule and soil sample respectively. These isolated organisms were blended with carrier material and kept in two different temperatures i.e. at room temperature and refrigerator to know the survivability of microorganisms in normal conditions and preserved condition. A decline in moisture and pH on prolonged incubation was observed in both organisms. A high survivable rate of Rhizobium species is seen in rice husk and Azotobacter species is seen in farmyard manure stored in both temperatures. Whereas least survivability was seen in charcoal for both organisms stored in both temperature. Moisture and pH are normally responsible for more 50% of change in CFU in all carrier material except for rice husk blended with Rhizobium and farm yard manure blended with Azotobacter stored in room temperature. CFU in all the carrier material with respect to storage and carrier material have significant difference except for Azotobacter stored in room temperature. The rhizobia and Azotobacter strains population significantly decline over time regardless of the carrier material and storage temperature. A decline in population on prolonged incubation may be attributed to the depletion of nutrients, moisture, and cell death. Rice husk, however, demonstrated extraordinary potential, particularly in respect of shelf life. KEYWORDS: Rhizobium, Azotobacter, carrier, biofertilizer