AGNES TUTIK PURWANI IRIANTI, AGUS SUYANTO*, SHINTA ROSALINA AND EDI KURNIADI
Department of Agrotechnology, Faculty of Agriculture, Science and Technology, Panca Bhakti University, Jl.
Kom Yos Sudarso, 78113 Pontianak, West Kalimantan, Indonesia
*(e-mail: agussuyanto@upb.ac.id; Mobile: 62811574462)
(Received: December 13, 2025; Accepted: January 27, 2026)
ABSTRACT
Edamame production in Indonesia remained sub-optimal, particularly in alluvial soils characterized by extreme acidity (pH 4.35), aluminium toxicity and limited microbial activity. This study evaluated the individual and interactive effects of Rhizobium sp. inoculation and rice husk biochar application on soil chemical properties, growth performance and yield of edamame in alluvial soil. A factorial randomized complete block design was employed with two factors: Rhizobium sp. inoculation (control, commercial Rhizoka and local isolate) and rice husk biochar rates (25, 50 and 75 g/polybag). No significant interaction was observed between factors. However, Rhizobium sp. significantly influenced compound leaf number, and highly significantly affected branch number, fresh pod number and pod weight. The local Rhizobium isolate demonstrated superior performance compared to commercial inoculant and control. Rice husk biochar significantly increased root nodule formation, with the highest rate (75 g/polybag) producing 6.0 nodules per plant compared to 4.7 in the lowest rate. Biochar application achieved substantial soil amelioration: pH increased by 1.33 units (4.35’!5.67 average), exchangeable aluminium decreased by 74% (1.05’!0.29 cmol(+)/kg) and organic carbon increased by 22% (1.41%’!1.72%). The optimal treatment combination R‚ Aƒ yielded 111.59 g/plant (equivalent to 11.2 t/ha), representing a 53% increase over control. Local Rhizobium isolate and rice husk biochar independently enhanced edamame productivity through complementary mechanisms, offering sustainable pathways for improving production in challenging tropical soil environments.
Key words: Biological nitrogen fixation, biochar amendment, edamame production, local rhizobia, root nodulation, sustainable agriculture