Assessment of spatial variability and mapping of soil properties for sustainable agricultural production using geographic information system techniques (GIS) oleh O.A. Denton, V.O. Aduramigba-Modupe, A.O. Ojo, O.D. Adeoyolanu, K.S. Are, A.O. Adelana, A.O. Oyedele, A.O. Adetayo, A.O. Oke