Populasi Bakteri Tanah pada Piringan Tanaman Kelapa Sawit Akibat Pemberian Pupuk NPK Komplit: Population of Soil Bacterial in The Oil Palm’s Weeded Circle Applied with NPK Complete Fertilizer

Biota tanah memainkan peranan penting dalam berbagai proses dalam tanah. Biota tanah meningkatkan pertumbuhan tanah sebagai pupuk anorganik, salah satunya adalah pupuk NPK komplit. Penelitian ini dilaksanakan untuk mempelajari populasi beberapa spesies bakteri pada piringan tanaman kelapa sawit di Desa Gajah Kecamatan Sei Balai Kabupaten Batubara. Penelitian ini merupakan penelitian survei dengan metode purposive sampling yang bertujuan membandingkan populasi bakteri tanah (Azotobacter spp., Bacillus spp. dan Lactobacillus spp.) pada piringan tanaman kelapa sawit. Penelitian ini dilakukan dengan mengambil 60 sampel tanah pada piringan tanaman kelapa. Hasil penelitian menunjukkan bahwa adanya perbedaan populasi bakteri Azotobacter spp. di sekitar piringan tanaman kelapa sawit yang telah diberikan pupuk NPK komplit dengan yang tidak diberikan pupuk NPK komplit. Hubungan antara kehadiran bakteri tanah terhadap sifat tanah terlihat bahwa Bacillus spp. mempengaruhi kadar air tanah dan total nitrogen tanah.   Soil biota plays an important role several processes in soil. They are enchancing plant growth as inorganic fertilizer such as NPK complete fertilizer. This research was conducted to study population of some species of bacteria at Gajah Village, Sei Balai Subdistrict, Batubara District. The research was a survey by purposive sampling method that aimed to compare soil bacterial population (Azotobacter spp., Bacillus spp. and Lactobacillus spp.) in the oil palm’s weeded circle. The research was done by taking 60 soil samples in the oil palm’s weeded circle. The result showed that the population of bacteria Azotobacter spp. around the weeded circle of oil palm applied with the NPK complete differed with the oil palm’s weeded circle that has not been given a NPK complete fertilizer. The relationship between the occurrences of soil bacteria with the soil properties showed that the presence of Bacillus spp. affected the water soil content and the nitrogen total.&nbsp