ABSTRAKTanah regosol umumnya memiliki kesuburan tanah rendah. Upaya perbaikan kesuburan tanah dapat dilakukan menggunakan pembenah tanah Tujuan penelitian untuk mengetahui pengaruh pembenah tanah terhadap biomasa bawang merah. Penelitian dilaksanakan di Kapanewon Kalasan, Kabupaten Sleman, Provinsi D.I. Yogyakarta pada Juni-Juli 2023. Rancangan penelitian menggunakan rancangan acak kelompok (RAK) diulang 3 kali. Bahan pembenah tanah dalam perlakuan ini terdiri dari H0:tanpa pembenah (kontrol); H1: pupuk kandang sapi 10 ton/ha; H2: arang sekam 5 ton/ha; H3: asam humat 3 kg/ha; H4: pupuk kandang sapi 5 ton/ha dan arang sekam 2.5 ton/ha; H5: pupuk kandang sapi 5 ton/ha dan asam humat 1.5 kg/ha; H6: asam humat takaran 1.5 kg/ha dan arang sekam 2.5 ton/ha dan H7: pupuk kandang sapi takaran 3.3 ton/ha; asam humat 1 kg/ha dan arang sekam 1.6 ton/ha. Hasil penelitian menunjukkan bahwa Bahan pembenah tanah tidak berpengaruh nyata terhadap jumlah daun, klorofil daun, kadar air relatif (KAR) daun, biomasa/rumpun (berat brangkasan segar dan kering jemur, umbi segar dan kering jemur; daun segar dan kering), berat/umbi dan jumlah anakan, namun berpengaruh nyata pada diameter umbi dan tinggi tanaman 3 dan 5 MST. Perlakuan H4 memberikan diameter umbi yang paling besar dibanding perlakuan yang lain, yaitu sebesar 28.16 mm. ABSTRACTRegosol generally has low soil fertility. Efforts to improve soil fertility can be carried out using soil amendments. The aim of the research is to determine the effect of soil amendments on shallot biomass. The research was conducted in Kapanewon Kalasan, Sleman Regency, D.I. Province. Yogyakarta in June-July 2023. The research design used a randomized block design (RAK) repeated 3 times. The soil amendment materials in this treatment consisted of H0: no amendment (control); H1: cow manure 10 tons/ha; H2: husk charcoal 5 tons/ha; H3: humic acid 3 kg/ha; H4: cow manure 5 tonnes/ha and husk charcoal 2.5 tonnes/ha; H5: cow manure 5 tons/ha and humic acid 1.5 kg/ha; H6: humic acid at a rate of 1.5 kg/ha and husk charcoal at a rate of 2.5 tonnes/ha and H7: cow manure at a rate of 3.3 tonnes/ha; humic acid 1 kg/ha and husk charcoal 1.6 tons/ha. The results showed that soil amendments had no significant effect on the number of leaves, leaf chlorophyll, relative water content (KAR) of leaves, biomass/clump (weight of fresh and sun-dried stover, fresh and sun-dried tubers; fresh and dry leaves), weight/ tubers and number of tillers, but had a significant effect on tuber diameter and plant height at 3 and 5 WAP. The H4 treatment provided the largest tuber diameter compared to the other treatments, namely 28.16 mm.