Potential test of non-symbiotic nitrogen-fixing bacteria in increasing nitrogen in Andisol soil

Abstract

Nitrogen (N) is one of the elements most needed by plants and widely distributed in nature. Nitrogen fixation can occur symbiotic or non-symbiotic by soil microbes. This research aimed to examine the potential of N-fixing microbes in increasing the availability of N in the soil. This research was conducted at the Soil Biology Laboratory of Faculty of Agriculture, Universitas Sumatera Utara. The results showed that the ability of microbes to increase the availability of N in the soil was varied. The population of N-fixing bacteria increased during 4 weeks of incubation. All bacterial isolates which incubated on Andisol soil were able to increase soil N-total content by around 9.4% -15.6%. The isolate with the most potential to increase soil N-total content was B6 isolate with an increase in total N content by 15.6%.