Matheus, Rupa, and Donatus Kantur. 2025. “Effectiveness of Organic Fertilizer Enriched With Humic Acid on Soil Chemical Quality, Nutrient Uptake, and Shallot Yield in Calcareous Soils”. Jurnal Teknik Pertanian Lampung (Journal of Agricultural Engineering) 14 (1):309-18. https://doi.org/10.23960/jtep-l.v14i1.309-318.