Effects of Microbial Inoculants and Organic Amendments on Wheat Nutrition and Development in a Variety of Soils

Abstract

Manipulation of soil microbial communities through inoculants or amendments can improve crop nutrition. However, to what extent these benefits vary depending on soil properties is not yet understood. Thus, here we studied the effects of microbial inoculants and the application of labile organic C on the yield and uptake of micronutrients and P in wheat (Triticum durum) in different soils. The application of Bacillus subtilis QST713, Trichoderma asperellum strain T34, and cellulose was tested in ten soils varying greatly in properties in a pot experiment. Microbial inoculants and cellulose increased dry matter (between 5 and 10%) and grain yield (between 15 and 20%), regardless of the soil. Some treatments triggered nutrient mobilization mechanisms such as phosphatase and oxalate production. However, total Zn and P in plants did not increase with treatments, and their effect on Fe and Mn varied depending on soils. The effect of B. subtilis and T. asperellum improving Fe uptake by plants decreased with increasing pH and also with decreased microbial activity in soil. Inoculants and cellulose increased the Zn harvest index and decreased the P-to-Zn ratio in grains independently of the soil. This was probably ascribable to changes in the distribution of phytohormones in plants. Microorganisms and cellulose improved wheat yield, the portion of absorbed Zn accumulated in grains, and grain quality. These effects did not depend on the soil. However, the effect on Fe and Mn nutrition was affected by soil pH and microbial activity.