PERAN GAMBUT TERHADAP NITROGEN TOTAL TANAH DI LAHAN RAWA The Role of Peat on Total Nitrogen in The Wetland Soils Arifin Fahmi 1 dan Bostang Radjagukguk 2 1 Badan Litbang Pertanian/BALITTRA, Jl. Kebun Karet, Loktabat Utara, Banjarbaru, 70712, Kalimantan Selatan, Tlp ; 085330118888, email ; Fahmi.nbl@gmail.com 2 Jurusan Tanah, Fakultas Pertanian Universitas Gadjah Mada ABSTRACT Peatland has important role in wetland ecosystem stability. Depletion and disappearance of peat layer lead to loss of potential source of nutrient and disruption of wetland ecosystem stability. The research aimed to study the influence of peat thickness and land hydrological condition on the total nitrogen (N) content in soil, the influence of rapidly or naturally the depletion and disappear of peat layer on total N content in soil, and the influence of hydrological condition on total N content in soil. Total N was observed in June of 2009 and 2010 (transition from wet to dry season), September of 2009 and 2010 (peak of dry season), and January of 2010 and 2011 (peak of wet season). The research was carried out on potential acid sulphate soil (A), peaty acid sulphate soil (B), shallow peat which all of peat layers were removed (C), shallow peat which peat layer was partially removed (D), shallow peat (E), moderate peat (F) and deep peat (G). The results showed that total N content increased with increasing of peat thickness, the depletion and disappearance of peat layer reduced total N content in soil, and declining in the groundwater level increased total N content in soil. Key words : Nitrogen, peat, and wetland ABSTRAK Lahan gambut memiliki peranan penting terhadap kestabilan ekosistem lahan rawa. Hilang dan menipisnya lapisan gambut menyebabkan hilangnya sumber hara dan mengganggu kestabilan ekosistem lahan rawa. Penelitian bertujuan mengetahui pengaruh ketebalan lapisan gambut terhadap kandungan N total tanah, mengetahui pengaruh menipisnya atau hilangnya lapisan gambut akibat penggalian lapisan gambut ataupun secara alamiah terhadap kandungan N total tanah, serta mengetahui pengaruh kondisi hidrologi lahan terhadap kandungan N total tanah. Nitrogen total diamati pada kondisi puncak musim hujan (MH) yaitu Januari 2010 dan 2011, kondisi lahan agak jenuh atau agak kering (T) dilaksanakan Juni 2009 dan 2010 dan kondisi paling kering (puncak MK) dilaksanakan Oktober 2009 dan 2010. Pada tahun pertama penelitian hanya dilaksanakan pada tanah gambut tipis (E), sedang (F), tebal (G). Sedangkan pada tahun kedua penelitian dilaksanakan pada tanah E, F, G, tanah sulfat masam bergambut (B), sulfat masam potensial (A), gambut tipis yang lapisan gambutnya di hilangkan sebagian (D), gambut tipis yang lapisan gambutnya dihilangkan seluruhnya (C). Hasil penelitian menunjukkan bahwa kandungan N total meningkat dengan peningkatan ketebalan gambut, hilang dan menipisnya lapisan