Kadar Amonium dan Populasi Bakteri Amonifikasi di Bawah Tegakan Acacia auriculiformis, Tectona grandis, dan Lahan Pertanian pada Musim Hujan di Gunungkidul

Rury Septyanda Putri, Dr. Ir. Handojo Hadi Nurjanto , M.Agr.Sc., IPU.; Dr. Arom Figyantika, S.Hut., M.Sc.,

2025 | Skripsi | KEHUTANAN

Kesuburan tanah merupakan faktor penting yang berpengaruh terhadap produktivitas tegakan. Semakin subur suatu tanah maka produktivitas tegakan akan semakin tinggi. Salah satu indikator kesuburan tanah yaitu adanya mikroorganisme tanah. Mikroorganisme tanah khususnya bakteri amonifikasi berperan dalam siklus nitrogen melalui proses amonifikasi yaitu mengubah nitrogen organik menjadi amonium (NH4+) yang tersedia dan dapat diserap tanaman. Penelitian ini bertujuan untuk menganalisis populasi bakteri amonifikasi dan kadar amonium tanah setelah ditanami pohon formis dan jati selama delapan tahun serta membandingkan dengan lahan pertanian tanpa vegetasi pohon.

Penelitian dilakukan pada bulan November 2024-Februari 2025. Sampel tanah diambil pada tegakan formis dan jati pada kedalaman tanah 0-10cm, 10-20cm, dan 20-30cm, serta diambil sampel tanah pertanian sebagai pembanding. Sumber variasi terdiri dari jenis tegakan dan kedalaman tanah. Hasil penelitian dianalisis menggunakan Analisis Varian (ANOVA). Kuantifikasi bakteri amonifikasi dan kadar amonium tanah dilakukan di Laboratorium Fisiologi Pohon dan Tanah Hutan, Fakultas Kehutanan, Universitas Gadjah Mada.

Hasil penelitian menunjukkan populasi bakteri amonifikasi tertinggi di bawah tegakan jati sebesar 7,91 Log sel/gram diikuti tegakan formis sebesar 7,56 Log sel/gram tanah, dan lahan pertanian 7,36 Log sel/gram tanah. Populasi bakteri amonifikasi menurun seiring bertambahnya kedalaman lapisan tanah. Kadar amonium tanah tertinggi pada lahan pertanian sebesar 82,56 mg/kg diikuti pada tegakan formis sebesar 79,85 mg/kg, dan tegakan jati sebesar 79,24 mg/kg. Kedalaman tanah tidak berpengaruh terhadap kadar amonium tanah. Kedalaman tanah tidak berpengaruh terhadap kadar amonium tanah.

Soil fertility is a crucial factor influencing stand productivity, the higher the soil fertility, the greater the stand producvtivity. One indicator of soil fertility is the presence of soil microorganisms. Soil microorganisms, particularly ammonification bacteria, play a role in the nitrogen cycle through the process of ammonification, which involves converting organic nitrogen into ammonium (NH??) that is available and can be absorbed by plants. This study aims to analyze the population of ammonification bacteria and the ammonium content in soil planted with formis and teak trees for eight years and compare them with agricultural land without tree vegetation.

The research was conducted from November 2024 to February 2025. Soil samples were taken from Formis and teak stands at depths of 0-10 cm, 10-20 cm, and 20-30 cm. The sources of variation consist of stand types and soil depth. The research results were analyzed using Analysis of Variance (ANOVA).The quantification of ammonification bacteria and ammonium content in the soil was carried out at the Tree and Soil Physiology Laboratory, Faculty of Forestry, Universitas Gadjah Mada. The research results were analyzed descriptively and quantitatively.

The results showed that the highest population of ammonification bacteria was found under the teak stand, with 7.91 log cells/gram, followed by the Formis stand at 7.56 log cells/gram, and agricultural land at 7.36 log cells/gram. The population of ammonification bacteria decreased with increasing soil depth. The highest soil ammonium concentration in agricultural land was 82.56?mg/kg, followed by 79.85?mg/kg in the formis stand, and 79.24?mg/kg in the teak stand. Soil depth had no effect on soil ammonium concentration. Soil depth did not affect the ammonium content in the soil.

Kata Kunci : Bakteri amonifikasi, kadar amonium, Formis, Jati, Lahan pertanian; Ammonification bacteria, Ammonium content, Formis, Teak, Agricultural land