The Combined Applications of Microbial Inoculants and Organic Fertilizer Improve Plant Growth under Unfavorable Soil Conditions

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 a two-year field experiment with different soil pH levels and available nutrients. Grain yield; contents of P, N, K, and Mg; and soil microbial parameters were measured. Grain yield and the content of nutrients were significantly increased by the applications of mineral fertilizer, organic fertilizer, AMF, and K. radicincitans, and the 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 the grain yield and content of nutrients of barley over the control.