Effects of solid biofertilizer containing potassium-solubilizing purple nonsulfur bacteria on potassium dynamics, growth, and yield of hybrid maize grown in dyked alluvial soils

Abstract This study was conducted to evaluate the effects of solid biofertilizer (SBF) containing potassium-solubilizing purple nonsulfur bacteria (K-PNSB), including Cereibacter sphaeroides M-Sl-09, Rhodopseudomonas thermotolerans M-So-11, and Rhodopseudomonas palustris M-So-14, on soil properties, K uptake, growth, and yield of hybrid maize cultivated in dyked alluvial soil collected from an Phu, An Giang. A two-factor experiment was arranged in a completely randomized design with four replications. The first factor was K fertilizer levels (0, 25, 50, 75, and 100 % of the recommended rate), and the second was SBF types (sterile water only, single strains M-Sl-09, M-So-11, M-So-14, or a mixture of all three strains). The application of SBF containing either single or mixed K-PNSB strains significantly enhanced soil exchangeable K, total K uptake, plant growth, and grain yield compared with the uninoculated control. The highest yield and total K uptake were recorded under 100 % K fertilizer combined with the three-strain SBF (106.5 g plant −1 ), demonstrating a strong synergistic interaction between biofertilizer and K application. These findings suggest that K-PNSB-based biofertilizer can improve potassium availability and maize productivity in nutrient-depleted dyked alluvial soils.