Microbial groups containing alkaline phosphatase accelerate soil phosphate mineralization in two soil patterns with contrasting pH levels

Low utilization rate of phosphorus (P) fertilizer seriously affects crop yield worldwide. Selection of different P fertilizers has a great effect in improving P conversion. This research assessed the impact of P fertilizer on P conversion in soils with different pH values and to determine the best fertilizer treatment.

We estimated the responses of ALP (alkaline phosphatase) activity, soil inorganic P fractions, and two functional genes phoD and pqqc to the application of chemical fertilizer, organic fertilizer, and mixed different proportions of organic–inorganic fertilizer in two soil patterns with contrasting pH levels based on an incubation experiment.

The highest ALP activities of 51.19 and 52.97 μg pNPP g⁻¹ soil h⁻¹ were obtained under the 3/4 OP (organic P fertilizer) treatment in neutral soils and the OP treatment in acid soils, respectively. Soil available P content was markedly increased in neutral soils (33.06–33.59 mg kg⁻¹) and acid soils (20.87–21.42 mg kg⁻¹) under mixed organic–inorganic fertilizer (1/2 OP and 3/4 OP) compared with chemical fertilizer alone in both soils. Furthermore, combined application of chemical and organic P fertilizers also significantly favored the growth of organic P (organophosphorus) –mineralizing and inorganic P–solubilizing bacterial phyla. Combined application of chemical and organic P fertilizers improved the nutrients requirement of microorganisms and provided a low P environment to promote microbial activity, increasing ALP activity and AP (available P) content.

Organic–inorganic fertilization affected the process of P conversion and ALP activity by altering the characteristics of microbial communities. This research pointed out that 3/4 organic fertilizer replacement could increase available P. Moreover, combined application of chemical and organic P fertilizers significantly enhanced the P supply potential in acid soils.