Phosphorus Use Management in Paddy Fields by Enriching Periphyton with Its Phosphate-Solubilizing Bacteria and Fungi at the Late Stage of Rice Growth

Phosphorus use efficiency (PUE) in paddy fields is low, and this fertilizer has lower availability to rice plants. Recently, the application of periphyton to regulate nutrient elements cycle especially P in paddy fields has received special attention. However, the effects of periphyton as well as phosphate-solubilizing microorganisms (PSM) on rice plant growth, P bioavailability, and its use management in calcareous soils have not been investigated. The aim of this study was to investigate the effects of periphyton and their effective PSM on P bioavailability, rice growth parameters, phosphatase activity, P fractionation, and P fertilizer efficiency in a calcareous soil fertilized or non-fertilized with chemical P fertilizer. The results showed that both natural periphytons and PSM-enriched periphytons decreased water-soluble P concentration at the early stages of rice growth but increased the concentration of water-soluble P and soil available P at the late stage of the plant growth. In periphyton treatments, the average pH of water and soil increased by 0.7 and 3 units, respectively. Periphytons led to an increase in the amount of easily available P species, such as Ca 2 -P, Ca 10 -P, and Al-P forms, in the calcareous soil. Periphytons also reduced P fixation in the soil and increased the PUE (2–29%) compared to the treatments without periphyton. The periphytons enriched with PSM showed the highest PUE at different levels of P fertilizer. Periphytons significantly increased rice growth parameters and P concentration in different parts of the rice by increasing soil available P concentration, soil organic matter, and soil acid and alkaline phosphatase activity. The use of periphyton enriched with PSM can increase PUE for rice in paddy fields. It seems that the use of PSM to decompose periphyton biomass and release accumulated P at the late stages of rice growth is the best strategy for using periphytons in paddy fields.