The performance of two bio inoculants either in single or in combined applications with organic fertilizer was tested to determine their effect on plant growth and yield under normal and unfavorable field conditions such as low pH value and low content of P. Arbuscular Mycorrhiza Fungi ((AMF; three species of Glomus) and the plant growth-promoting bacterial strain Kosakonia radicincitans DSM16656 were applied to barley in two years field experiment with different soil pH levels and available nutrients. Grain yield, content of P, N, K, Mg, and soil microbial parameters were measured. Grain yield and content of nutrients were significantly increased by the applications of mineral fertilizer, organic fertilizer, AMF, K. radicincitans, and combined application of organic fertilizer with AMF and with K. radicincitans over the control under normal growth conditions. Under low pH and low P conditions, only the combined application of the organic fertilizer with K. radicincitans and organic fertilizer with AMF could increase grain yield and content of nutrients of barley over the control.