Electronic Theses and Dissertation

Tandan kosong kelapa sawit (TKKS) merupakan limbah padat hasil pengolahan kelapa sawit yang tersedia dalam jumlah melimpah di Indonesia, namun pemanfaatannya masih terbatas. Padahal, TKKS berpotensi dimanfaatkan sebagai amandemen organik untuk memperbaiki sifat kimia dan biologi tanah. Tanah Inceptisol umumnya memiliki kandungan bahan organik, kapasitas tukar kation (KTK), dan ketersediaan unsur hara yang relatif rendah sehingga memerlukan upaya perbaikan melalui pemberian bahan organik. Penelitian ini bertujuan untuk mengetahui pengaruh pemberian tandan kosong kelapa sawit (TKKS) dalam bentuk segar, kompos, biochar, dan abu terhadap sifat kimia dan biologi tanah Inceptisol serta menentukan bentuk TKKS yang memberikan respons terbaik. Penelitian dilaksanakan pada bulan Desember 2025 hingga April 2026 menggunakan Rancangan Acak Lengkap (RAL) nonfaktorial yang terdiri atas lima perlakuan, yaitu kontrol (P0), TKKS segar (P1), TKKS kompos (P2), TKKS biochar (P3), dan TKKS abu (P4), dengan lima ulangan sehingga diperoleh 25 satuan percobaan. Dosis TKKS yang digunakan adalah 5% atau setara dengan 50 g kg⁻¹ tanah, kemudian diinkubasi selama 60 hari pada kelembapan sekitar 60% kapasitas lapang. Parameter yang diamati meliputi pH tanah, C-organik, N-total, P-tersedia, kapasitas tukar kation (KTK), respirasi tanah, dan total mikroorganisme tanah. Data dianalisis menggunakan analisis ragam (ANOVA) dan dilanjutkan dengan uji beda nyata terkecil (BNT) pada taraf 5%.
Hasil penelitian menunjukkan bahwa pemberian berbagai bentuk TKKS berpengaruh nyata terhadap C-organik, P-tersedia, kapasitas tukar kation (KTK), dan total mikroorganisme tanah, tetapi tidak berpengaruh nyata terhadap pH tanah, N-total, dan respirasi tanah. Perlakuan TKKS biochar menghasilkan C-organik tertinggi sebesar 1,38%, P-tersedia tertinggi sebesar 24,39 mg kg⁻¹, dan total mikroorganisme tanah tertinggi sebesar 6.609.415,4 CFU g⁻¹ tanah. Perlakuan TKKS kompos menghasilkan nilai kapasitas tukar kation (KTK) tertinggi sebesar 27,12 cmol(+) kg⁻¹ serta N-total tertinggi sebesar 0,09%, meskipun tidak berbeda nyata dengan perlakuan lainnya. Perlakuan TKKS abu menghasilkan nilai pH tertinggi sebesar 8,17 dan respirasi tanah tertinggi sebesar 6,844 mg CO₂ kg⁻¹ hari⁻¹, namun kedua parameter tersebut tidak berbeda nyata antarperlakuan. Berdasarkan hasil penelitian dapat disimpulkan bahwa setiap bentuk TKKS memberikan respons yang berbeda terhadap sifat kimia dan biologi tanah Inceptisol. Pada kondisi penelitian ini, TKKS biochar merupakan bentuk amandemen organik yang paling efektif dalam meningkatkan C-organik, P-tersedia, dan total mikroorganisme tanah, sedangkan TKKS kompos paling efektif dalam meningkatkan kapasitas tukar kation (KTK).
Kata kunci: amandemen organik, biochar, Inceptisol, kompos, sifat biologi tanah, sifat kimia tanah, tandan kosong kelapa sawit (TKKS).

Oil palm empty fruit bunches (OPEFB) are solid wastes generated from the palm oil processing industry and are abundantly available in Indonesia; however, their utilization remains limited. In fact, OPEFB has considerable potential to be used as an organic amendment to improve the chemical and biological properties of soil. Inceptisol soils generally have low organic matter content, cation exchange capacity (CEC), and nutrient availability, thus requiring improvement through the application of organic amendments. This study aimed to evaluate the effects of fresh, composted, biochar, and ash forms of oil palm empty fruit bunches (OPEFB) on the chemical and biological properties of Inceptisol soil and to determine the most effective form of OPEFB. The study was conducted from December 2025 to April 2026 using a non-factorial Completely Randomized Design (CRD) consisting of five treatments, namely control (P0), fresh OPEFB (P1), OPEFB compost (P2), OPEFB biochar (P3), and OPEFB ash (P4), with five replications, resulting in 25 experimental units. OPEFB was applied at a rate of 5% or 50 g kg⁻¹ of soil, followed by a 60-day incubation period at approximately 60% of field capacity. The observed parameters included soil pH, organic carbon, total nitrogen, available phosphorus, cation exchange capacity (CEC), soil respiration, and total soil microorganisms. The data were analyzed using analysis of variance (ANOVA), followed by the Least Significant Difference (LSD) test at the 5% significance level. The results showed that the application of different forms of OPEFB significantly affected soil organic carbon, available phosphorus, cation exchange capacity (CEC), and total soil microorganisms, but had no significant effect on soil pH, total nitrogen, and soil respiration. OPEFB biochar produced the highest organic carbon content (1.38%), available phosphorus (24.39 mg kg⁻¹), and total soil microorganisms (6,609,415.4 CFU g⁻¹ soil). OPEFB compost resulted in the highest cation exchange capacity (27.12 cmol(+) kg⁻¹) and the highest total nitrogen content (0.09%), although the latter did not differ significantly from the other treatments. OPEFB ash produced the highest soil pH (8.17) and soil respiration rate (6.844 mg CO₂ kg⁻¹ day⁻¹); however, both parameters did not differ significantly among treatments. It can be concluded that each form of OPEFB produced different responses in improving the chemical and biological properties of Inceptisol soil. Under the conditions of this study, OPEFB biochar was the most effective organic amendment for increasing soil organic carbon, available phosphorus, and total soil microorganisms, whereas OPEFB compost was the most effective in improving cation exchange capacity (CEC). Keywords: biochar, chemical properties, compost, Inceptisol, oil palm empty fruit bunches (OPEFB), organic amendment, soil biological properties.