Amirrullah, J., Hutapea, Y., Ratmini, N., & Prabowo, A. (2020). Farmer Mentoring in Determining Fertilization Dosage of Corn Plants (Zea Mays L.) Using Soil Test Equipment. Jurnal Lahan Suboptimal : Journal of Suboptimal Lands, 9(1), 102–108. https://doi.org/10.33230/JLSO.9.1.2020.437