Hubei Key Laboratory of Soil Environment and Pollution Remediation, College of Resources and Environment, Huazhong Agricultural University, No. 1 Lion Hill Street, Hongshan District, Wuhan 430070, PR China.
Hubei Key Laboratory of Soil Environment and Pollution Remediation, College of Resources and Environment, Huazhong Agricultural University, No. 1 Lion Hill Street, Hongshan District, Wuhan 430070, PR China.
Sci Total Environ. 2020 Jun 25;723:138006. doi: 10.1016/j.scitotenv.2020.138006. Epub 2020 Mar 17.
The use of biochar to amend soil has been gaining increasing attention in recent years. In this study, the N tracer technique was used together with elemental analysis-stable isotope ratio analysis and gas isotope mass spectrometry to characterise biochar, soil, plant, and gas samples in order to explore the nitrogen transport mechanisms in the biochar-soil-plant-atmosphere system during the process of returning biochar to the soil (RBS). The results showed that the nitrogen retention rate of biochar was negatively correlated with the pyrolysis temperature during the preparation process, but was less affected by the pyrolysis atmosphere. In the RBS process, the migration of biochar nitrogen to plants was significantly greater than that of straw nitrogen, and it showed an overall decreasing trend with the increase in pyrolysis temperature, but was less influenced by the pyrolysis atmosphere. At temperatures of 300-500 °C, the pyrolysis atmosphere had a slightly smaller effect on the migration of biochar nitrogen to the air, plant, and soil system, and the pyrolysis temperature was much more important. However, the activation with CO gas at a higher temperature (600 °C) significantly enhanced the pore structure of biochar, particularly the structure of small pores; therefore, biochar prepared under a CO atmosphere at 600 °C reduces gaseous nitrogen emissions better than that under a N atmosphere. In the future, more pyrolysis conditions should be examined and their optimal combination should be further explored to reduce gaseous nitrogen emissions.
近年来，利用生物炭来改良土壤的做法越来越受到关注。本研究采用氮示踪技术，结合元素分析-稳定同位素比分析和气体同位素质量光谱法，对生物炭、土壤、植物和气体样品进行了特征描述，以探索生物炭返回土壤（RBS）过程中生物炭-土壤-植物-大气系统中氮素迁移机制。结果表明，生物炭的氮保留率与制备过程中的热解温度呈负相关，但受热解气氛的影响较小。在 RBS 过程中，生物炭氮向植物的迁移明显大于秸秆氮，且随着热解温度的升高呈总体下降趋势，但受热解气氛的影响较小。在 300-500°C 的温度范围内，热解气氛对生物炭氮向空气、植物和土壤系统的迁移影响较小，而热解温度则更为重要。然而，在更高的温度（600°C）下用 CO 气体进行的活化作用显著增强了生物炭的孔隙结构，特别是小孔结构；因此，在 600°C 下在 CO 气氛下制备的生物炭比在 N 气氛下制备的生物炭能更好地减少气态氮的排放。在未来，应该研究更多的热解条件，并进一步探索其最佳组合，以减少气态氮的排放。
