Abstract: “This study has been conducted in an agricultural hilly area of Karo District, in North Sumatera Province, Indonesia. The study was conducted in May until July 2016. The objective of this study is to analyse slurry characteristics as organic fertilizer in which biogas is used to yield better slurries. Five biodigesters were used with 5 differents designs of mix materials: T1) 100% cow feces, T2) 75% cow feces + 25% argicultural waste, T3)50% cow feces + 50% agricultural waste, T4) 25% cowfeces + 75% agricultural waste, and T5)100% agricultural waste. The parameters measured were slurry production and slurry chemical compositions including N,P ,K, pH, and C/N.The result showed that T1 and T2 were better in chemical compositions( N,P,K, pH and C/N) while all treatments produce equal volume of slurry. It is suggested that local farmers use the composition of T1 and T2 when using biogas technology in supporting organic fertilizer. It is noteworthy that this first study is continued with the”

Keywords: slurry, agriculture, NPK, pH, C/N