Phosphorus fractions in biochar-amended soil — chemical sequential fractionation, ³¹P NMR, and phosphatase activity

ABSTRACT

In this study, we assessed the effects of biochar application for five years on soil phosphorus (P) factions by chemical sequential P fractionation, phosphatase activity, and ³¹P NMR. Four treatments were included in this research: two biochar (0 and 2.63 t ha⁻¹) levels blended with two P fertilizer levels (0 and 26 kg P ha⁻¹), respectively. We found elevated levels of soil pH, total carbon (C), and total P in soil exposed to biochar. The inorganic (Ca₈ – P, Al – P, Fe – P, and Ca₁₀ – P) and organic (LOP and HROP) P fractions were all enhanced by biochar regardless of the application of P fertiliser. ³¹P NMR spectra further showed that ortho – P, monoester – P, and diester – P levels in the soil with added biochar combined with P fertiliser were 464.5 mg kg⁻¹, 74.3 mg kg⁻¹, and 13.9 mg kg⁻¹, respectively, which were the highest among all treatments. Biochar application increased alkaline phosphomonoesterase activity by 24.4–32.7% and decreased phosphodiesterase activity by 10.2–11.0%. In conclusion, biochar application significantly improves soil P fractions and regulates phosphatase activity.

KEYWORDS:

• Biochar
• P fractions
• ³¹P NMR
• phosphatase activity

Abbreviations

Table

Acknowledgements

This work was financially supported by the National Natural Science Foundation of China (grant no. 41401325), the Natural Science Foundation of Liaoning Province (grant no. 20180550247), the National Key Research and Development Project (grant no. 2018YFD0300308).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [41401325]; National Key Research and Development Project [2018YFD0300308]; The Natural Science Foundation of Liaoning [20180550247].