PENGARUH DOSIS KOMPOS TANDAN KOSONG KELAPA SAWIT DAN PUPUK NPK TERHADAP PERTUMBUHAN DAN HASIL BAWANG MERAH (Allium ascalonicum L.) Effects of oil palm empty bunch compost dose and NPK fertilizer on growth and yields of onion (Allium ascalonicum L.) Irwandi1, Erida Nurahmi2, Marai Rahmawati2 1Alumni Fakultas Pertanian Universitas Syiah Kuala 2Tenaga Pengajar Fakultas Pertanian Universitas Syiah Kuala ABSTRAK Pengaruh dosis kompos tandan kosong kelapa sawit dan pupuk NPK terhadap pertumbuhan dan hasil bawang merah (Allium ascalonicum L.) di bawah bimbingan Erida Nurahmi selaku pembimbing utama dan Marai Rahmawati selaku pembimbing anggota. Penelitian dilaksanakan di Kebun Percobaan Fakultas Pertanian Universitas Syiah Kuala, yang berlangsung dari Januari sampai Maret 2015. Penelitian ini menggunakan Rancangan Acak Kelompok (RAK) pola faktorial 3 x 3 dengan tiga ulangan. Faktor yang diteliti adalah dosis kompos tandan kosong kelapa sawit yang terdiri atas 3 taraf yaitu 10, 20 dan 30 ton ha-1, dan dosis pupuk NPK yang terdiri atas 3 taraf yaitu 500, 800 dan 1100 kg ha-1. Hasil penelitian menunjukkan bahwa dosis kompos tandan kosong kelapa sawit berpengaruh tidak nyata terhadap semua parameter yang diamati. Perlakuan pupuk NPK berpengaruh sangat nyata terhadap jumlah umbi per rumpun, bobot umbi kering angin per rumpun, berpengaruh nyata terhadap jumlah anakan per rumpun umur 28 dan 56 hari setelah tanam serta bobot basah tanaman per rumpun, berpengaruh tidak nyata terhadap tinggi tanaman umur 14, 28 dan 42 HST, jumlah anakan per rumpun umur 42 HST serta potensi hasil. Terdapat interaksi yang tidak nyata antara perlakuan dosis kompos tandan kosong kelapa sawit dengan perlakuan pupuk NPK terhadap pertumbuhan dan hasil tanaman bawang merah. Kata Kunci : Bawang merah, Kompos tandan kosong kelapa sawit, Pupuk NPK ABSTRACT Effects of oil palm empty bunch compost dose and NPK fertilizer on growth and yields of onion (Allium ascalonicum L.) under supervision of Erida Nurahmi as main supervisor and Marai Rahmawati as cosupervisor. Study was conducted in Experimental Garden of Agriculture Faculty of Syiah Kuala University, taken place from January to March 2015. This study used Randomized Block Design by factorial pattern 3 x 3 with 3 replications. Factor investigated was oil palm empty bunch compost dose which comprise of 3 levels they were 10, 20, and 30 tons ha-1, and dose of NPK fertilizer comprise of 3 levels were 500, 800, and 1100 kg ha-1. Results of study indicated that dose of oil palm empty bunch compost has not significant effect on all parameters observed. Treatment of NPK fertilizer has most significant effect on amount of tuber per clump, weight of air dried tuber per clump, has significant effect on amount of shoots per clump of 28 and 56 days after planting and wet weight plant per clump, has not significant effects on height of plant in age 14, 28 and 42 Days after planting, amount of shoots per clump in age 42 days after planting and yield potential. There was not significant interaction between treatment of oil palm empty bunch compost dose to the treatment of NPK fertilizer for growth and yield of onion. Keywords : Onion, Oil palm empty bunch compost, NPK fertilizer