Organic Fertilizer Substitution Promoted the Organic Carbon Sequestration in Calcareous Fluvisol: A Study Based on Acid Hydrolysis and Attenuated Total Reflectance-Fourier Transform Infrared Spectroscopy (ATR-FTIR)

ABSTRACTThis study aimed to elucidate the mechanism of substituting organic fertilizer for mineral fertilizer to increase calcareous fluvisol soil organic carbon. Four years of soil culture experiments were conducted, wheat yield, soil nutrients, soil organic carbon (SOC) and SOC fractions were measured and the compositional changes of SOC was analyzed by attenuated total reflectance-fourier transform infrared (ATR-FTIR) spectroscopy. Treatments included applying no fertilizer (CK), mineral N and P fertilizers (CF) and organic fertilizers to replace 6% (OF6), 12% (OF12), 18% (OF18) and 24% (OF24) of N and P under the same nutrient conditions. The results showed that the OF24 treatment was the best among the treatments employed. Compared with CF, wheat yield, SOC, microbial biomass carbon (MBC), labile fraction 1 (LOC1) and recalcitrant fraction (ROC) of OF24 increased by 10.4%, 24.4%, 66.3%, 43.2% and 30.7%, however, the labile fraction 2 (LOC2) decreased by 16.8%. ATR-FTIR results showed that the relative absorption intensity of OF24 treatment at 1,000 cm−1 band is lower than CK and CF treatment, other bands are higher than CK and CF treatment. Overall, OF24 treatment not only significantly increased wheat yield, but also increased the content of LOC1 and MBC. The increase of MBC can improve the soil microbial environment and promote the decomposition of LOC2, while also accelerate the turnover rate of soil carbon and then show the increase of ROC content and improve the proportion of the recalcitrant carbon pool.KEYWORDS: Commercial organic fertilizersoil improvementsoil organic carbon fractionswheat AcknowledgementsWe thank to Prof. Junhua Li for his useful comments in the preparation of this manuscript.Disclosure statementNo potential conflict of interest was reported by the author(s).Compliance with ethical standardsThis article does not contain any studies with human participants performed by any of the authors.Additional informationFundingThis research was supported by the National Key Research and Development Program of China, Project No. 2021YFD1900802, and Department of Resources and Environmental Science, Shihezi University, Shihezi, Xinjiang, People’s Republic of China.