<![CDATA[Abstrak. Lahan sub optimal merupakan lahan yang memiliki produktivitas rendah. Lahan sub optimal terbagi menjadi lahan basah dan lahan kering. Rendahnya hara menjadi faktor pembatas dalam pengembangan lahan kering menjadi wilayah pertanian. Nitrogen merupakan hara esensial yang sangat diperlukan tanaman. Penggunaan tanaman leguminosae yang mampu bersimbiosis dengan bakteri penambat nitrogen dapat meningkatkan ketersediaan nitrogen dalam tanah. Penelitian ini bertujuan untuk mengetahui populasi bakteri penambat nitrogen dan hubunganya terhadap N-total tanah pada beberapa lokasi budidaya lahan kering. Penelitian dilakukan di lahan budidaya kacang panjang pada lima lokasi di Kabupaten Situbondo. Variabel Pengamatan meliputi : populasi bakteri penambat nitrogen, N-total, pH, C-organik dan C/N rasio. Hasil menunjukkan Lahan budidaya di Kecamatan Banyuglugur memiliki populasi bakteri dan nilai N-total tertinggi. Analisis korelasi regresi menunjukkan erdapat hubungan yang erat antara populasi bakteri penambat nitogen dengan N-total. Bakteri penambat nitrogen mempengaruhi ketersediaan nitrogen sebesar 61,72%, sedangkan 32,28 % dipengaruhi oleh faktor lain.Abstract. Sub optimal land has low productivity. Sub optimal land is divided into wetlands and dry lands. Low nutrients are a limiting factor in the development of dry land into agricultural areas. Nitrogen is an essential nutrient that is needed by plants. Legume plants can symbiosis with nitrogen fixing bacteria to increase the availability of nitrogen in the soil. This study aims to determine the population of nitrogen fixing bacteria and their relationship to soil N-total in several cultivation locations. The research was conducted in long bean cultivation at five locations in Situbondo Regency. Observation variables include: nitrogen fixing bacterial population, N-total, pH, C-organic and C / N ratio. The results showed that the cultivated land in Banyuglugur District had the highest bacterial population and N-total value. The regression correlation analysis showed that there was a close relationship between the nitogen-fixing bacterial population and total N. Nitrogen fixing bacteria affect nitrogen availability by 61.72%, while 32.28% was influenced by other factors.]]>
