Azolla pinnata ammendment and P-solubilizing bacteria inoculation for improving Inceptisols fertility and rice (Oryza sativa L.) yield production

Continuous and long-term use of chemical fertilizers in lowland rice fields can have negative impacts on the environment, causing harm to aquatic life and a decrease in soil health. Applying Azolla pinnata and inoculating phosphate solubilizing bacteria (PSB) in organic farming is an appropriate strategy to increase soil nutrients and lowland rice production. Azolla pinnata plays a role in increasing N nutrients, while phosphate solubilizing bacteria (PSB) increase available phosphate in the soil. This study aims to assess the effectiveness of varying doses of Azolla pinnata and PSB inoculant in increasing soil available P, plant-P concentration, plant hegh, productive tiller, and rice yield. The experimental design used a Factorial Randomized Block Design of two factors in three replications. The first factor was Azolla pinnata application (0 ton ha-1; 10 ton ha-1; 20 ton ha-1; 30 ton ha-1), and the second factor was PSB inoculation (0 kg ha-1; 12.5 kg ha -1; 25 kg ha-1). The experimental results showed that the Azolla pinnata application at a dose of 10 t ha-1 with inoculation of 12.5 kg ha-1 PSB significantly increased the highest soil available P by 48.3 ppm. The application of Azolla pinnata 30 t ha-1 significantly increased the P content of plants—0.26 mg g-1. Azolla pinnata 30 t ha-1 application and PSB inoculation produced significantly the highest productive tillers of rice plants, 38 plants pot-1. Azolla pinnata 10 tons ha-1 application with BPF inoculant 12.5 kg ha-1 significantly increased the highest grain yield, namely 81.47 g pot.-1