Authors:
Isnaniar Rahmatul Azizah, Rahmatia Harahap, Betty Natalie Fitriatin, Nadia N. Kamaluddin and Tualar Simarmata ,Indonesia |
Abstract:
Soil microbial communities are crucial in ecosystem diversity and are directly related to soil
fertility. Lombok is an island in central Indonesia that has low soil fertility and a limited amount
of available water. Beneficial microorganisms can be used as a low-cost and environmentalfriendly tool to increase productivity in dryland agriculture systems. Screening to obtain superior
rhizosphere bacteria is one of the options to support the nutrient supply in arid soils. Composites
soil samples were taken from five ecosystems in Lombok, West Nusa Tenggara, an arid region in
the eastern part of Indonesia to obtain the isolates of nitrogen-fixer rhizobacteria (NFR). Nine
Azotobacter and Azopirillium spp were isolated from, rainfed, maize, mixed crop, natural
forests, and savanna ecosystems. Abundance of total bacteria and N2-fixers in all ecosystems
was relatively high (more than 108 cfu g-1), and the highest total population was recorded in the
natural forest. The abundance of N2-fixer rhizobacteria recorded the highest Azotobacter
population at 2.64 x 108 cfu g-1 in the maize ecosystem and the highest Azospirillum population
at 2.32 x 108 cfu g-1 in the natural forest ecosystem. Additionally, the highest contain of organic
C and total nitrogen were obtained in natural forest and savanna ecosystem. Eighteen isolates
were obtained and characterized microscopic and macroscopically, consisted of nine Azotobacter
sp and nine Azospirillium isolates which are potentially to be used as biogent for improving the
growth of upland rice on dry climate zone. |
