Performing Spatial Variabilityof Peat Depth by Using Geostatistics Mohd. Zuhdi, M. Edi Armanto, Dedi Setiabudidaya and Ngudiantoro E3S Web Conf., 68 (2018) 04021 Published online: 27 November 2018 DOI: 10.1051/e3sconf/20186804021