ABSTRACT This research aimed to determine the relation of nutrients K and soil organic carbon to the intensity of basal stem rot (Ganoderma sp.) on PT. PD. PATI Aceh Tamiang. This research was conducted at the Laboratory Socfin Indonesia North Sumatera and Soil Biology Laboratory, Faculty of Agriculture, University of North Sumatera, Medan in May 2015 through September 2015. Soil sampling was done by using Purposive Sampling, analysis of K nutrient used K2O extract HCl 25%, analysis of soil organic carbon used Walkey and Black method and interpreted into nutrient status map. The data were processed using correlation and regression. The results showed that the intensity of basal stem rot (Ganoderma sp.) was positively correlated with K. Potassium enable explain its effect on the basal stem rot (Ganoderma sp.) by 16.8%. Keywords: Basal Stem Rot (Ganoderma sp.), Correlation and Regression, Organic Carbon, Potassium, Purposive Sampling ABSTRAKPenelitian ini bertujuan untuk mengetahui hubungan sebaran hara K dan C-organik tanah terhadap intensitas serangan penyakit busuk pangkal batang (Ganoderma sp.) di perkebunan kelapa sawit PT. PD. PATI Kabupaten Aceh Tamiang. Penelitian ini dilakukan di Laboratorium Socfin Indonesia Sumatera Utara dan Laboratorium Biologi Tanah Fakultas Pertanian, Universitas Sumatera Utara, Medan pada Mei 2015 hingga September 2015. Pengambilan contoh tanah dilakukan dengan menggunakan metode Purposive Sampling, analisis hara K mengunakan K2O ekstrak HCl 25% dan analisis kandungsn C-organik menggunakan metode Walkey and Black serta menginterpretasikannya dalam bentuk peta. Data diolah dengan menggunakan uji korelasi dan regresi. Hasil penelitian menunjukkan bahwa intensitas penyakit busuk pangkal batang (Ganoderma sp.) berkolerasi positif dengan K. Kadar K tanah berkemampuan menjelaskan pengaruhnya terhadap intensitas penyakit busuk pangkal batang (Ganoderma sp.) sebesar 16.8%. Kata Kunci : Busuk Pangkal Batang (Ganoderma sp.), C-organik, kalium, Korelasi dan Regresi, Purposive Sampling