Despite the fact that erosion undermines productivity in the Ethiopian highlands, adoption of fertility enhancing techniques remained very minimal. The objectives of this study is to examine factors affecting adoption of fertilize and manure use and their interrelationships using plot and household level data collected from 211 farm households. A two-stage probit model results revealed a negative reciprocal relationship between fertilizer use and manure applications, basically because of the difference in additional resource requirements for application of the two inputs. Whereas prices of chemical fertilizers are very high in the study area, manure is labor-intensive in its application. This implies that the ability to afford high fertilizer prices decreases the probability to apply manure; and endowment with adequate labor input decreases the probability to opt for fertilizer. The study also identified different impediments to adoption of fertilizer use and manure applications and important implications drawn from the results are discussed.