Analisis Indeks Kualitas Tanah pada Lahan Pertambangan Emas Rakyat Sangon II, Kalirejo, Kokap, Kulon Progo

Alvian Tegar Wiranda, Prof. Dr. Ir. Sri Nuryani Hidayah Utami, M.P., M.Sc ; Dr. Ir. Eko Hanudin, M.P., IPU, ASEAN Eng.

2025 | Skripsi | ILMU TANAH

Penelitian ini bertujuan untuk menilai Indeks Kualitas Tanah (IKT) pada berbagai kondisi lahan, meliputi lahan bekas tambang emas rakyat dengan usia yang berbeda, lahan tambang aktif, dan lahan pertanian. Analisis regresi stepwise digunakan untuk mengidentifikasi parameter tanah yang paling berpengaruh terhadap IKT. Selain itu, diberikan rekomendasi pengolahan tanah guna mengoptimalkan lahan sebagai area pertanian. Sampel tanah diambil dari Dusun Sangon II, Desa Kalirejo, Kecamatan Kokap, Kabupaten Kulon Progo, yang mewakili berbagai kondisi lahan: bekas tambang emas selama 8, 16, dan 20 tahun; tambang aktif; serta lahan pertanian sebagai kontrol. Penilaian IKT dilakukan dengan metode skoring berdasarkan Minimum Data Set, menggunakan skor antara 1 (terendah) hingga 5 (tertinggi). Sebanyak 11 sifat tanah dianalisis, mencakup sifat fisik (tekstur, berat volume, porositas), kimia (pH, nitrogen total, fosfor tersedia, kalium tersedia, kapasitas pertukaran kation, karbon organik, dan merkuri), serta sifat biologi tanah (respirasi tanah). Nilai rerata IKT pada lahan bekas tambang 8 tahun, 16 tahun, dan 20 tahun; tambang aktif; serta lahan pertanian berturut-turut adalah 22,73; 22,73; 20,00; 18,79; dan 29,39. Rendahnya nilai IKT terutama disebabkan oleh pencemaran merkuri dari proses amalgamasi bijih emas. Hasil regresi stepwise menunjukkan bahwa fosfor tersedia, karbon organik, porositas, kalium tersedia, dan respirasi tanah sangat mepengaruhi IKT. Rekomendasi pengolahan tanah di lokasi penelitian adalah penggunaan hasil penggilingan bijih emas yang dicampur biochar untuk meningkatkan kesuburan dan kualitas tanah.

This study aims to assess the Soil Quality Index (SQI) under various land conditions, including abandoned artisanal gold mining sites of different ages, an active mining area, and agricultural land. Stepwise regression analysis was employed to identify the soil parameters that most significantly influence SQI. Additionally, soil management recommendations were proposed to optimize land for agricultural use. Soil samples were collected from Dusun Sangon II, Kalirejo Village, Kokap Subdistrict, Kulon Progo District, representing five land conditions: gold mining areas abandoned for 8, 16, and 20 years; an active mining site; and agricultural land as a control. SQI was evaluated using a scoring method based on the Minimum Data Set, with scores ranging from 1 (lowest) to 5 (highest). Eleven soil properties were analyzed, including physical (texture, bulk density, porosity), chemical (pH, total nitrogen, available phosphorus, available potassium, cation exchange capacity, organic carbon, and mercury), and biological (soil respiration) characteristics. The average SQI scores for the 8-year, 16-year, and 20-year abandoned sites, active mining site, and agricultural land were 22.73, 22.73, 20.00, 18.79, and 29.39, respectively. The low SQI values were primarily attributed to mercury contamination from gold ore processing using the amalgamation method. Stepwise regression results indicated that available phosphorus, organic carbon, porosity, available potassium, and soil respiration were the most influential factors affecting SQI. As a recommendation, the application of gold ore milling residues mixed with biochar is suggested to improve soil fertility and quality in the study area.

Kata Kunci : indeks kualitas tanah, tambang emas rakyat, amalgamasi, merkuri.