Enhancement of Green Soybean Growth and Yield in Alluvial Soil by Potent N-fixing Rhizospheric Bacteria.

<b>Background and Objective:</b> Nitrogen fertilizer causes adverse effects on the environment aspect, so biological nitrogen sources should be applied in agriculture. The objective of the study was to evaluate the efficacy of N₂-fixing rhizospheric bacteria in improving soil fertility, nitrogen (N) uptake, growth and yield of green soybean (<i>Glycine max</i> (L.) Merr). <b>Materials and Methods:</b> The pot experiment was conducted with 9 treatments (i) 100% N of recommendation of fertilizer formula (RFF), (ii) 85% N, (iii) 70% N, (iv) 55% N, (v) 85% N and a mixture of <i>Enterobacter cloacae</i> ASD-07 and ASD-28, (vi) 70% N and a mixture of ASD-07 and ASD-28, (vii) 55% N and a mixture of ASD-07 and ASD-28, (viii) 0% N and ASD-07 and ASD-28, and (ix) 0% N, without bacteria<i>,</i> with four replications in in-dyke alluvial soil collected from Chau Phu District, An Giang Province. <b>Results:</b> The use of a mixture of the two N₂-fixing rhizospheric strains<i> </i>as biofertilizers at 85% N level improved NH₄⁺ content and N uptake with an increase of 3.1 mg kg¹ and 95.8 mg pot¹, respectively. They also produced higher values in growth including plant height, number of leaves, stem diameter and yield components including pod number, pod diameter, seed length, seed diameter and seed thickness. <b>Conclusion:</b> The application of a mixture of the two N₂-fixing rhizospheric strains resulted in replacing 15% N of RFF, but it still improved the yield.