In this study composting of yard trimmings and sheep manure using windrow system wasrncarried out at Ilala Gojo Sira-Ati Youths Den Lemat Mahiber nursery site at WelmerarnWoreda in Oromiya National Regional State. Composting of on-farm biodegradablerninputs helps to produce compost that maintain the biogeochemical cycles of nutrients.rnCompost is an organic fertilizer that is applied to amend soil physical and chemicalrnproperties. This study mainly focused on the composting of yard trimmings with sheeprnmanure using windrow composting system and determined the major plant nutrient (N-PK)rncontent including pH, EC, OM and C:N ratio changes during the composting processrnand in the final end product. For this purpose three treatment windrows with replicaternwere constructed in the ratio1:1 grass clippings and sheep manure, 2:1 yard trimmingsrnand sheep manure and 2:1 sheep manure and yard trimmings, coded as P11, P21 and P12rnrespectively. Temperature was daily monitored for 70 days during composting. Therncomposting temperature at the early stages had risen to the thermophilic temperature thatrnindicated process functioning and latter gradually declined to the ambient temperature inrnthree of treatment windrows. The composite samples of treatment windrows werernanalyzed for selected parameters to evaluate the composting process functioning and thernend product quality. The results were analyzed using descriptive statistics and one-wayrnanalysis of variance. The mean values of analysis results of each parameter indicated thernpresence of differences between treatment windrows. Generally, during the compostingrnperiod the total nitrogen exhibited an increasing trend while potassium, phosphorus,rnelectrical conductivity, organic matter and C:N ratio showed decreasing trend. The OM,rnTN, TP, Exchangeable K in percent and EC values in mS/cm of the matured composts ofrntreatment windrows ranges from 14.33-20.78, 0.87-1.12, 0.18-0.32, 0.75-1.35 and 3.45-rn5.79 respectively. Treatment windrow P21 resulted in better quality compost in terms ofrnthe nutrient content and salinity level followed by P11 and P12 which was relativelyrnlower in quality. The maturity of the compost was evaluated based on the observation ofrnphysical parameters and by carrying out germination tests.rnKey words: compost, composting, compost quality, electrical conductivity, nitrogen,rnpotassium, phosphorus, organic matter, yard trimming, and manure.