Amirrullah, J., Hutapea, Y., Ratmini, N. and 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), pp. 102–108. doi: 10.33230/JLSO.9.1.2020.437.