Impact of fertilizer, salinity, and exo-electrogen bacteria on the performance of plant microbial fuel cell (PMFC) using rice plant (Oryza sativa)

Saline soil paddy agriculture becomes a prominent solution to increase rice production. However, high salinity level, low inorganic nutrient availability, and the absence of halophilic bacteria incorporating inorganic nutrient especially nitrogen become a challenge for a successful saline soil agriculture. We conducted a set of mesocosm research using plant microbial fuel cell (PMFC) systems, four levels of fertilizer (cultivation without fertilizer, 100% NPK dose, combination of compost and NPK fertilizer), bacterial inoculation (Staphylococcus saprophyticus ICBB 9554, Citrobacter freundii ICBB 9763, and co-culture of both), and salt addition (salt addition only on anode area, salt addition entire of soil). In addition, we used no paddy, fertilizers, and salt for control. We aimed to investigate the impact of fertilizer, salinity, and addition of exo-electrogenic bacteria for the PMFC performance and paddy growth. The result showed that paddy plant cultivation increased electricity generation two times due to the release of rhizodeposits compared to control without paddy plant. Secondly, a high concentration of mineral fertilizers 2 dS/m negatively impacts power output. Thus, the compost addition + 50% NPK fertilizer was suggested to balance electricity generation and paddy plant growth. Finally, salinity and exo-electrogenic bacteria resulted in positive impacts on electricity generation, with co-culture inoculation and salt addition on the anode area reaching the highest electricity production at an average voltage and power density of 646.17 mV/reactor and 0.22 mW/reactor, respectively. This study provides valuable insight that PMFC can be applied in saline soil paddy agriculture by complementing the halotolerant rice variety and the utilization of bacterial inoculates.