Populasi Bakteri Pelarut Fosfat dan Kadar P-Tersedia di Bawah Tegakan Acacia Auriculiformis di Bleberan, Playen, Gunungkidul, Yogyakarta

Ken Falah Syahnur, Dr. Ir. Handojo Hadi Nurjanto, M.Agr.Sc. ; Ir. Arom Figyantika, S.Hut., M.Sc., Ph.D.

2026 | Skripsi | KEHUTANAN

Ketersediaan fosfor pada tanah vertisol berkapur sangat terbatas akibat fiksasi oleh kalsium, sehingga peran bakteri pelarut fosfat (BPF) menjadi krusial dalam mengonversi fosfat tidak larut menjadi bentuk tersedia bagi tanaman. Penelitian ini bertujuan menganalisis pengaruh tegakan Acacia auriculiformis umur 2 tahun dan kedalaman tanah terhadap populasi BPF serta kadar P-tersedia di Bleberan, Playen, Gunungkidul.

Penelitian menggunakan rancangan dua faktor: penggunaan lahan (tegakan A. auriculiformis vs. lahan kosong, tiga ulangan) dan kedalaman tanah (0–10, 10–20, 20–30 cm), dengan total 18 sampel komposit. Populasi BPF dihitung dengan metode plate count pada media selektif Pikovskaya, dan kadar P-tersedia dianalisis dengan metode Olsen. Data dianalisis menggunakan ANOVA dua arah dan uji lanjut DMRT (? = 0,05).

Hasil menunjukkan bahwa tegakan A. auriculiformis berpengaruh nyata terhadap populasi BPF (p = 0,002) dan berpengaruh sangat nyata terhadap kadar P-tersedia (p < 0>A. auriculiformis sebesar 6,92 × 10? CFU g?¹ tanah (6,84 Log CFU g?¹ tanah) nyata lebih tinggi dibandingkan lahan kosong sebesar 1,20 × 10? CFU g?¹ tanah (6,08 Log CFU g?¹ tanah), dengan populasi tertinggi 95,7 × 10? CFU g?¹ tanah pada kedalaman 0–10 cm. Kadar P-tersedia lahan tegakan (37,74 ppm) nyata lebih tinggi daripada lahan kosong (15,58 ppm), dengan nilai puncak 64,52 ppm pada lapisan 0–10 cm. Kedalaman tanah berpengaruh sangat nyata terhadap kedua variabel (p < 0>Acacia auriculiformis berpotensi memperbaiki kesuburan biologis dan kimia tanah vertisol kawasan karst Gunungkidul, sehingga layak dipertimbangkan sebagai jenis rehabilitasi lahan marginal.

Phosphorus availability in calcareous Vertisols is severely limited by calcium fixation, making phosphate-solubilizing bacteria (PSB) critical for converting insoluble phosphate into plant-available forms. This study analyzed the effect of a 2-year-old Acacia auriculiformis stand and soil depth on PSB population and available P content in Bleberan, Playen, Gunungkidul.

A two-factor design was employed: land use (A. auriculiformis stand vs. open land, three replications) and soil depth (0–10, 10–20, 20–30 cm), yielding 18 composite samples. PSB population was enumerated by the plate count method on Pikovskaya selective medium, and available P was determined by the Olsen method. Data were analyzed by two-way ANOVA and DMRT post-hoc test (? = 0.05).

The results indicated that A. auriculiformis stands significantly increased the population of phosphate-solubilizing bacteria (PSB) (p = 0.002) and highly significantly increased soil available phosphorus (P) content (p < 0>. Mean log PSB population under the stand 6.84 Log CFU g?¹ soil (6,92 × 10? CFU g?¹ soil) was significantly higher than in open land 6.08 Log CFU g?¹ soil (1,20 × 10? CFU g?¹ soil), peaking at 95.7 × 10? cells g?¹ soil at the 0–10 cm depth. Available P under the stand (37.74 ppm) significantly exceeded that of open land (15.58 ppm), with the highest value of 64.52 ppm recorded at 0–10 cm. Soil depth significantly affected both variables (p < 0>Acacia auriculiformis demonstrates potential for improving the biological and chemical fertility of Vertisol in the Gunungkidul karst area and may be recommended as a rehabilitation species for phosphorus-limited marginal lands.

Kata Kunci : bakteri pelarut fosfat, Acacia auriculiformis, fosfor tersedia, tanah vertisol, rizosfer, kedalaman tanah