Phosphorus reuse by application of biochar is a recent concept that needs to be supported by long-term field data. To monitor biochar's long-term effects on P turnover, one-off biochar was applied in 2013 with mineral NPK fertilizers being applied every year since then. Biochar application rates included 0 t ha-1 (CK), 15.75 t ha-1 (BC1), 31.5 t ha-1 (BC2), and 47.25 t ha-1 (BC3). Over the 5 years' field experiment, P distribution in soil profile, inorganic and organic P fractions in bulk, and rhizosphere soil and maize P uptake were determined. The results showed that biochar reduced the inorganic P fractions (Ca2-P, Ca8-P, Al-P, Fe-P and O-P by 4.8-33.7%, 8.8-59.0%, 13.7-28.6%, 8.4-17.6%, and 3.3-25.5%, respectively), and increased organic P fractions (MLOP and HROP by 67.2-11.6% and 18.8-87.7%, respectively) in bulk soil, while in rhizosphere soil, Fe-P and MLOP were decreased by 13.4-34.5% and 67.2-111.6%, respectively, in 2017. After the application of biochar for 5 years, moderately labile organic phosphorus (MLOP), moderately resistant organic phosphorus (MROP), and highly resistant organic phosphorus (HROP) with different biochar treatments were enhanced by 12.8-42.7%, 20.1-48.0%, and 5.5-66.6%, respectively, but Ca8-P, Al-P, O-P, and Ca10-P were all decreased by 18.6-24.9%, 16.4-21.4%, and 3.3-23.48%, respectively. Total P storage in 0-100 cm was declined by biochar. Increases in maize P uptake in the stover (38.6-71.3%) and grain (20.9-25.5%) were occurred after 31.5 t ha-1 and 47.25 t ha-1 biochar addition. To sum up, biochar is found to regulate the distribution, storage, and transformation of soil P, which lead to increase in maize P uptake.

Agronomy College Shenyang Agricultural University Shenyang 110866 China

Biology Center Institute of Soil Biology and SoWa Research Infrastructure Czech Academy of Science Na Sadkach 7 37005 Ceske Budejovice Czech Republic

College of Information and Electrical Engineering Shenyang Agricultural University Shenyang 110866 China

College of Resources and Environmental Engineering Ludong University Yantai 264025 China

Liaoning Agricultural Information Technology Center Shenyang 110866 China

Liaoning Biochar Engineering and Technology Research Center Shenyang 110866 China

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