Nitrogen species specific phosphorus mineralization in temperate floodplain soils

Mary R Arenberg,Yuji Arai

doi:10.1038/s41598-021-96885-5

Mary R Arenberg, Yuji Arai

Open Access

https://doi.org/10.1038/s41598-021-96885-5

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Abstract

As an essential component of enzymes, higher N availability from agricultural runoff to forest soils may boost the activity of phosphatase, increasing the bioavailability of phosphate. The objective of this study was to evaluate P mineralization rates in temperate floodplain soils as a function of inorganic N species (i.e., ammonium and nitrate) and amendment rate (1.5–3.5 g N kg−1). Accordingly, the soil was amended with nitrate and ammonium, and P dynamics were monitored during a 40-day incubation. The addition of ammonium significantly boosted acid and alkaline phosphatase activity by 1.39 and 1.44 µmol p-nitrophenol P (pNP) g−1 h−1, respectively. The degree of increase was positively correlated with the amendment rate. Likewise, the P mineralization rate increased by 0.27 mg P kg−1 in the 3.5 g N kg−1 ammonium treatment. 31P nuclear magnetic resonance spectroscopic analysis further supported the reduction in organic orthophosphate diesters on day 30. Meanwhile, the addition of nitrate promoted P mineralization to a lesser degree but did not increase phosphatase activity. While floodplain soils have great potential to sequester anthropogenic P, high availability of inorganic N, especially ammonium, could promote P mineralization, potentially increasing P fertility and/or reducing P the sequestration capacity of floodplain soils.

Highlights

As an essential component of enzymes, higher N availability from agricultural runoff to forest soils may boost the activity of phosphatase, increasing the bioavailability of phosphate
Mineralization regulates the transformation of organic P into bioavailable orthophosphate[4,5]
Higher N availability may boost the activity of phosphatase, the enzyme that carries out the mineralization of organic P into bioavailable orthophosphate[14,15,16]

Summary

Introduction

As an essential component of enzymes, higher N availability from agricultural runoff to forest soils may boost the activity of phosphatase, increasing the bioavailability of phosphate. N additions boosted phosphatase activity in a far greater number of soils, including in agricultural, forest, and grassland systems[16,22,23,24,25,26,27,28,29]. Based on these contradicting responses, it was hypothesized that the form of N added and/or its amendment rate could have resulted in variable phosphatase response. While the effects of N on phosphatase activity have been extensively studied, the broader impacts on biological P cycling (e.g., rate of P mineralization, organic P concentration, and P speciation) have been seldomly investigated. It has been hypothesized that N deposition may delay the onset of P limitation as soils a ge[32,34]

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Conclusion