A field experiment was conducted on Nitisols of Asossa Agricultural Research Centre during 2017/18 to 2018/2019 cropping season toinvestigate the response of yieldpartial budget analysis to biofertilizer rates.The N fertilizer treatments considered in the study consisted of six levels (rates) of biofertilizer, one nationally recommended inorganic N and negative control of N.The treatments consists of: 125 g ha-1 (T1), 250 g ha-1 (T2), 500 g ha-1(T3), 625 g ha-1(T4), 750 g ha-1(T5), 900 g ha-1 (T6), negative control (T7) and 18kg N ha-1. The treatments were laid out as a Randomized Complete Block Design with three replications.The analysis of variance revealed that bio-fertilizer
rates significantly (P < 0.01) affected grain yield at Begi district, while non-siginificant (p<0.05) at Asossa district. The maximum (3483.7 kg ha-1and 1750.9 kg ha-1
) grain yield was recorded from 500 g ha-1bio-fertilizer at Begi and Asossa districtrespectively. The application of 500 g ha- 1biofertilizer had the highest net-benefit of 20850.8 ETB, followed by 125 g ha -1biofertilizer which also had a total of 20196.8 ETB net benefit at Asossa district, while the application of 500 g ha- 1biofertilizerhad the highest net-benefit of 41644.4 ETB, followed by 125 g ha-1biofertilizer which also had a total of 38315.6 ETB net benefit at Begi district. The application of 500 g ha-1
bio-fertilizerha-1 had highest net benefit. Therefore, we recommended the treatment 500 g ha-1 since it produced high marginal rate of return, high net benefit and relatively small total cost of production, for soybean production in Begi and Asossa area.
