Analysis of Functional Genes and Microbial Community Relevant to N2O Emission in Dent Corn Fields

Pradipta Guntur Putra, Ir. Donny Widianto, Ph.D., Prof. Dr. Toru Watanabe, Ph.D.

2023 | Skripsi | MIKROBIOLOGI PERTANIAN

Emisi N2O pada jagung gigi telah menjadi isu mendesak yang terlibat dalam meningkatnya suhu bumi. Emisi N2O ini terutama terjadi karena nitrifikasi dan denitrifikasi oleh aktivitas mikroba di tanah budidaya. Studi ini menggunakan gen fungsional nitrifikasi (amoA(AOB) dan amoA(AOA)), gen fungsional denitrifikasi (nirS, nirK, norB, dan nosZ), serta identifikasi komunitas berbasis 16S rRNA untuk menyelidiki aktivitas nitrifikasi dan denitrifikasi pada ladang jagung gigi yang diolah dengan enam perlakuan pemupukan. Perlakuan pemupukan melibatkan tanpa pemupukan (CT), pupuk kimia (CF), pupuk kandang babi (PM), pupuk kandang babi dengan penambahan tulang (PM+B), lumpur tinja kompos (CS), dan lumpur tinja kompos dengan penambahan tulang (CS+B). Studi ini menemukan bahwa perlakuan pemupukan hanya memengaruhi nirK secara signifikan (p<0>Pseudomonas, Bacillus, Rhodococcus, Agrobacter, Rhizobium, Balneimonas, dan juga Dechloromonas sebagai bakteri penting dalam reduksi N2O pada ladang jagung gigi.

N2O emission in dent corn has been an urgent issue involved in rising earth temperature. This N2O emission mainly occurs due to the nitrification and denitrification by the microbial activity in the cultivation soil. This study used the nitrification functional gene (amoA(AOB) and amoA(AOA)), denitrification functional gene (nirS, nirK, norB, and nosZ), and 16S rRNA-based community identification to investigate the nitrification and denitrification activity in dent corn fields treated with 6 fertilization treatments. The fertilization treatments including no fertilization (CT), chemical fertilizer (CF), pig manure (PM), pig manure with bone meal addition (PM+B), composted sewage sludge (CS), and composted sewage sludge with bone meal addition (CS+B). This study discovered that the fertilization treatments only affect nirK significantly (p<0>nirS+nirK/nosZ ratio on the CF indicating there is a higher N2O production activity due to the higher nitrogen release by the CF. In opposite, organic fertilizer tends to lower the N2O production activity. Denitrification seems to be the main source of the N2O emission in dent corn fields due to the significant correlation (p<0>nirS (0.50*), nirK(0.67**), and nosZ (0.63**) with N2O emission. Higher activity on CF was also projected on the higher nitrifying bacteria (1.94×108 copies 16S rRNA.g dry soil-1) and denitrifying bacteria (3.11×108 copies 16S rRNA.g dry soil-1) abundance found in the community. This study found some important nitrifying-denitrifying and denitrifying bacteria that play an important role in N2O production, such as Pseudomonas, Bacillus, Rhodococcus, Agrobacter, Rhizobium, Balneimonas, and also Dechloromonas as an important bacteria in N2O reduction in dent corn fields.

Kata Kunci : N2O emission, dent corn, fertilization, functional gene, microbial community