Abstract: We explored the effects of the application of exogenous phytase and phosphate liberation bacteria in a cropland of maize, with the following treatments, no fertilization (CK), conventional fertilization (F100), and 20% reduced phosphorus fertilization (F80), adding exogenous phytase (F80S1), phosphate liberation bacteria (F80S2), and a combination of exogenous phytase and phosphate liberation bacteria (F80S3) under reduced phosphorus fertilization. The effects of exogenous phytase or phosphate liberation on soil phosphorus availability, soil phosphatase activity, maize yield, and phosphorus uptake were examined. The results showed that compared to solely reducing phosphorus (F80) treatment, the F80S1, F80S2, and F80S3 treatments increased maize yield and phosphorus uptake. In 2021, the F80S1 treatment significantly increased the inorganic phosphorus content in the 0-10 cm soil layer compared to F100 and F80, while the treatments with other phosphorus regulators showed no significant impact on the contents of soil phosphorus fractions. There was a trend of increasing soil available phosphorus content and the ratio of inorganic phosphorus to organic phosphorus (P_i/P_o). Soil phosphatase activity in the phosphorus regulator treatments showed no significant difference compared to F80. In 2022, compared to F80 treatment, F80S1 and F80S3 treatments significantly increased soil available phosphorus and total phosphorus contents in the 0-10 cm soil layer, as well as soil inorganic phosphorus and total phosphorus contents in the 10-20 cm soil layer. F80S1 and F80S3 treatments significantly decreased soil alkaline phosphatase and phosphodiesterase activities in the 0-10 cm soil layer. Results of correlation analysis showed that soil available phosphorus and organic phosphorus contents were significantly negatively correlated with soil phosphatase activity and significantly positively correlated with soil inorganic phosphorus content in the 0-10 cm soil layer. In the 10-20 cm soil layer, alkaline phosphatase and phosphodiesterase activities were significantly negatively correlated with soil available phosphorus and organic phosphorus contents, and significantly positively correlated with soil inorganic phosphorus and total phosphorus contents. Soil acid phosphatase activity was positively correlated with soil inorganic phosphorus and total phosphorus contents. In summary, exogenous phytase and phosphate liberation bacteria can effectively increase soil available phosphorus content, thereby promoting maize yield and phosphorus uptake. The combined application of exogenous phytase and phosphate liberation bacteria inoculants is better than the single application.

Key words: exogenous phytase, phosphate liberation bacteria, available phosphorus, soil enzyme activity