Karakterisasi Biologis dan Respirasi Tanah Gambut pada Zona Pengelolaan di Perkebunan Kelapa Sawit

Abstract

Lahan gambut di Indonesia termasuk dalam gambut tropis yang terbentuk dari akumulasi tumbuhan berkayu pada suhu yang relatif hangat dan curah hujan yang sangat tinggi. Lahan gambut banyak dimanfaatkan sebagai perkebunan kelapa sawit yang memiliki manajemen pengelolaan berupa zona piringan dan gawangan mati. Perbedaan manajemen pengelolaan di perkebunan kelapa sawit ini diduga memengaruhi kondisi biologi dan kimia antarzona pengelolaan yang berimplikasi pada kondisi lingkungan, contohnya emisi gas CO2. Tujuan dari penelitian ini adalah menganalisis total mikrob, fungi, dan respirasi tanah gambut pada piringan dan gawangan mati di dua blok perkebunan kelapa sawit, serta mengidentifikasi faktor pengaruhnya antarzona pengelolaan dan antarblok perkebunan kelapa sawit. Sampel tanah gambut diambil di Desa Mertasari, Kecamatan Pedongga, Kabupaten Pasangkayu, Provinsi Sulawesi Barat. Pengambilan tanah dilakukan di dua blok, yakni OC08 dan OL02 dengan rincian plot: piringan (P) pada kedua blok, gawangan mati (GM) pada OC08, gawangan mati perlakuan tandan kosong kelapa sawit (GM-TKKS) pada OL02, dan kontrol (G) pada kedua blok. Analisis populasi total mikrob dan fungi menggunakan metode Total Plate Count (TPC), sementara laju respirasi menggunakan metode Verstaete. Hasil menunjukkan bahwa populasi total mikrob tertinggi pada GM sebesar 11,70 x 108 CFU/g BKM dan pada P di blok OL02 sebesar 4,92 x 108 CFU/g BKM. Sementara total fungi tertinggi pada P di blok OC08 sebesar 1,71 x 105 CFU/g BKM dan GM-TKKS sebesar 1,76 x 105 CFU/g BKM. Laju respirasi tertinggi terdapat pada GM sebesar 18,14 mg C-CO2/kg tanah/hari dan GM-TKKS sebesar 20,08 mg C-CO2/kg tanah/hari. Hasil tersebut diduga dipengaruhi oleh beberapa faktor seperti akumulasi pelepah kelapa sawit, eksudat akar, dan pemupukan.

Peatlands in Indonesia are classified as tropical peatlands, formed by the accumulation of woody vegetation in relatively warm temperatures and under conditions of very high rainfall. Peatlands are widely utilised as oil palm plantations, which employ management practices involving palm circle and interrow zones. Differences in management practices within these oil palm plantations are suspected to influence biological and chemical conditions among management zones, which in turn affect environmental conditions, such as CO2 emissions. The objective of this study was to analyse total microbial populations, fungi, and soil respiration in peatland palm circle plots and interrow areas across two blocks of oil palm plantations, as well as to identify influencing factors among management zones and plantation blocks of oil palm plantations. Peat soil samples were taken in Mertasari Village, Pedongga Sub-district, Pasangkayu District, West Sulawesi Province. Soil samples were collected from two blocks, namely OC08 and OL02, with the following plot details: palm circle (P) in both blocks, interrow aera (GM) in OC08, interrow area with empty fruit branches application (GM-TKKS) in OL02, and controls (K) in both blocks. Analysis of total microbial and fungal populations used the Total Plate Count (TPC) method, whilst respiration rates were measured using the Verstaete method. The results showed that the highest total microbial population was found in the GM plots at 11,70 × 108 CFU/g oven-dry soil and in the P plots in block OL02 at 4,92 × 108 CFU/g oven-dry soil. Meanwhile, the highest total fungal population was found in P in block OC08 at 1,71 × 105 CFU/g oven-dry soil and in GM-TKKS at 1,76 × 105 CFU/g oven-dry soil. The highest respiration rate was observed in GM at 18,14 g C-CO2/kg soil/day and in GMTKKS at 20,08 g C-CO2/kg soil/day. These results are thought to be influenced by several factors, such as the accumulation of oil palm fronds, root exudates, and fertilisation.