Effect of Exogenous Phosphatases Addition on Phosphorus Uptake by Maize and Phosphorus Activation in Red Soil

Purpose To investigate the effects of different exogenous phosphatase addition on phosphorus (P) uptake by maize and P activation in red soil.

Methods Through a pot experiment, conventional cultivation without enzyme addition was used as the control (CK) to investigate the effects of adding exogenous acid phosphatase (ACP), alkaline phosphatase (ALP), and phytase (PHY) to low-P red soil on the rhizosphere soil enzyme activity, soil P pool fractions, and P uptake by maize.

Results The addition of exogenous ACP, ALP, and PHY increased ACP activity in the maize rhizosphere by 24.4%, 19.6%, and 69.8%, respectively; increased ALP activity by 16.8%, 19.2%, and 20.9%, respectively. The addition of exogenous PHY significantly increased PHY activity in the soil by 95.3%. Exogenous addition of ACP and PHY treatments significantly increased maize P accumulation by 31.6% and 66.2%, respectively, and dry matter weight by 15.6% and 38.7%, respectively; while exogenous ALP showed no significant promoting effect. The PHY treatment had the greatest impact on soil P fractions, followed by ACP and ALP. Compared to CK, the PHY treatment significantly reduced NaHCO₃-Po and NaOH-Po in maize rhizosphere soil by 13.9% and 6.8%, respectively, and significantly increased Resin-P and NaHCO₃-Pi by 337.8% and 65.2%, respectively. Compared to ACP and ALP treatments, the PHY treatment significantly increased Resin-P by 90.1% and 104.3%, NaHCO₃-Pi by 30.6% and 45.2%, and significantly reduced NaHCO₃-Po by 8.8% and 11.4%, and NaOH-Po by 3.5% and 4.4%, respectively. The relative contribution rate of NaHCO₃-Pi, NaHCO₃-Po and Resin-P to available P in red soil were 10.0%, 8.7% and 8.4%, respectively.

Conclusion The addition of exogenous PHY and ACP significantly promotes the conversion of organic P (NaHCO₃-Po and NaOH-Po) in red soil into water-soluble inorganic P (Resin-P) and available inorganic P (NaHCO₃-Pi), enhancing P uptake and utilization by maize. These enzymes play a crucial role in promoting maize P uptake and P activation in red soil.