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

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