Podzolik merah kuning termasuk tanah tua dengan tingkat pelapukan lanjut, pencucian intensif, dan kesuburan kimia, fisika, serta biologi yang sangat rendah. Kendala sifat fisika podzolik merah kuning yang kurang baik, diantaranya daya pegang air rendah, tekstur lempung berliat, struktur kurang mantap dan permeabilitas makin kebawah makin rendah. Penelitian ini bertujuan untuk mengetahui pengaruh jenis pembenah tanah organik terhadap perubahan sifat fisika tanah Podzolik Merah Kuning dan mendapatkn jenis pembenah tanah yang mampu memberikan perubahan sifat fisika tanah yang terbaik. Penelitian dilakukan di lahan penelitian dan Labortorium Fakultas Pertanian Universitas Borneo Tarakan. Penelitian ini menggunakan rancangan acak kelompok (RAK) dengan satu faktor. Terdiri dari 10 perlakuan yaitu P0 (tanah tanpa perlakuan), P1 (Kotoran sapi 15 t/ha), P2 (Kotoran Sapi 30 t/ha), P3 (Kotoran sapi 45 t/ha), P4 (Arang sekam 15 t/ha), P5 (Arang sekam 30 t/ha), P6 (Arang sekam 45 t/ha), P7 (Cocopeat 15 t/ha), P8 (Cocopeat 30 t/ha), P9 (Cocopeat 45 t/ha). Setiap perlakuan diulang sebanyak 3 kali sehingga diperoleh 30 satuan. Percobaan dari setiap satuan percobaan terdiri dari 5 polybag. Parameter yang diamati meliputi kadar lengas, porositas, permeabilitas, berat jenis, berat volume, suhu tanah dan warna tanah. Penelitian ini menunjukkan bahwa pemberian bahan pembenah tanah organik seperti kotoran sapi, arang sekam, dan cocopeat dapat memperbaiki sifat fisika tanah. Penambahan bahan organik terbukti meningkatkan kadar air, porositas tanah, serta menurunkan berat volume dan berat jenis tanah sehingga kemampuan tanah dalam menahan dan menyediakan air meningkat Pada penelitian ini pembenah tanah kotoran sapi dan arang sekam merupakan bahan pembenah tanah yang memberikan pengaruh terbaik dalam memperbaiki sifat fisika tanah.
Kata kunci : Tanah podzolik merah kuning, pembenah tanah organik, sifat fisika tanah

Yellowish Red Podzolic soil is classified as an old soil type characterized by advanced weathering, intense leaching, and very low chemical, physical, and biological fertility. The major physical constraints of this soil type include low water-holding capacity, clayey texture, unstable structure, and decreasing permeability with soil depth. This study aims to assess the effects of different types of organic soil amendments on the physical properties of Yellowish Red Podzolic soil and to identify the most effective amendment in improving soil physical conditions. The research was conducted at the research field and laboratory of the Faculty of Agriculture, Borneo University Tarakan. A randomized complete block design (RCBD) with a single factor was employed, consisting of 10 treatments: PO (untreated soil), P1 (cow manure 15 t/ha), P2 (cow manure 30 t/ha), P3 (cow manure 45 t/ha), P4 (rice husk biochar 15 t/ha), P5 (rice husk biochar 30 t/ha), P6 (rice husk biochar 45 t/ha), P7 (cocopeat 15 t/ha), P8 (cocopeat 30 t/ha), and P9 (cocopeat 45 t/ha). Each treatment was replicated three times, resulting in 30 experimental units, each comprising five polybags. Observed parameters included soil moisture content, porosity, permeability, specific gravity, bulk density, soil temperature, and soil color. The findings indicate that the application of organic soil amendments such as cow manure, rice husk biochar, and cocopeat significantly improved soil physical properties. The addition of organic materials increased soil moisture and porosity while reducing bulk density and specific gravity, thereby enhancing the soil's capacity to retain and supply water. Among the amendments tested, cow manure and rice husk biochar were found to be the most effective in improving the physical properties of Yellowish Red Podzolic soil. Keywords: Yellowish Red Podzolic soil, organic soil amendment, soil physical properties