RESUMEN
In the Mekong Delta Vietnam, rice is heavily affected by Al3+ and Fe2+ ions appearing in local acid sulfate soils (AAS). Therefore, the current study was carried out to assess the efficacy of a liquid biofertilizer (LB) containing nitrogen-fixing and phosphorus-solubilizing bacterial strains of Rhodopseudomonas spp. on remediation of soil characteristics and improvements of rice uptakes, growth, and yield. The experiment was designed in a randomized block design with nine treatments and four replications in an ASS. The results have shown that the LB application could contribute to the remediation of soil properties, including an increase in concentrations of NH4+ by 12.9%-19.4%, soluble P by 25.7%-42.6%, total N uptake by 40.7-64.0 kg ha-1 and total P uptake by 5.60-12.6 kg ha-1, and a decrease in concentrations of toxins, such as Al3+ by 12.1%-19.7% and Fe2+ by 16.6%-19.0%, compared to the treatment with the farmer-based fertilization. Thereby, grain yield was improved by 31.9%-32.2% with the LB versus the treatments without the bacteria and by 9.5%-11.1% compared to the commercial biofertilizer treatments. The application of LB reduced 25% N and 50% P of the recommendation versus the farmers' fertilization and improved performance of rice growth and yield cultivated on ASS which suffered from Al3+ and Fe2+ ions.
The current study has introduced the potential of the Rhodopseudomonas palustris TLS06, VNW02, VNW64, and VNS89 strains in performance as a bioremediator and a biofertilizer. The strains have shown their ability to recover acid sulfate soils, which had damaged the yield of rice plants due to high concentrations of Al3+ and Fe2+ ions. The work has delivered a biological approach to improve acid sulfate soil fertility and rice productivity in Vietnam and in other parts of the world, which have similar conditions, to achieve sustainable agriculture and food security.