ABSTRACT This field experiment was conducted to evaluate the effect of fertilizer type and plant spacing on plant morphology, biomass yield and chemical composition of brachiaria hybrid mulato II grass grown in lowland of northwest Ethiopia. The experimental design used was a 3×3 factorial layout in a randomized complete block design with three replications giving a total of 27 plots, each measuring 2×2 m2. The plant spacing were 15, 30 and 45cm between plants and fertilizer types were commercial (NPS), manure and control. Morphological parameters such as plant height (PH), leaf length per plant (LLPP), number of leaves per plant (NLPP), number of tillers per plant (NTPP), leaf stem ratio( LSR), number of roots per plant (NRPP),root length per plant (RLPP), root circumference(RC), leaf area index (LAI), biomass yield and chemical composition were collected based on established methods. All data were subjected to GLM ANOVA following the procedures of SAS version 9.0. The result indicated that there was no significant interaction between main factors. Most of the morphological parameters were significantly affected (P<0.05) by the type of fertilizer and plant spacing. Similarly significant (P<0.05) difference were observed in most of chemical composition of the grass by fertilizer type; but not by plant spacing. However, ADF and ADL were not affected (P>0.05) by effect of fertilizer. The highest CP (11.08%) and biomass yield (18.28t/ha) were obtained from NPS fertilized grass. More CP% (11.06) content was recorded for larger plant spacing but the reverse was for biomass yield (11.22t/ha. It can be concluded that fertilizer types has its own significant contribution on the brachiaria grass morphology and chemical composition grown in the lowland area. NPS fertilizer is recommendable for brachiaria hybrid production if it is accessible by smallholder farmers, otherwise, the use of manure could be an alternative in the study area and in similar environments elsewhere in Ethiopia. Moreover, for better biomass production 30cmx50cm planting space is recommended. Key word: Brachiaria, Chemical composition, Fertilizer type, morphological characteristics, plant spacing