Jiangsu Provincial Key Lab for Organic Solid Waste Utilization, Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University , Nanjing 210095, PR China.
Department of Crop and Soil Science, Oregon State University , ALS Building 3017, Corvallis, Oregon 97331, United States.
Environ Sci Technol. 2017 May 2;51(9):4960-4969. doi: 10.1021/acs.est.7b00305. Epub 2017 Apr 20.
Mineral binding is a major mechanism for soil carbon (C) stabilization, and mineral availability for C binding critically affects C storage. Yet, the mechanisms regulating mineral availability are poorly understood. Here, we showed that organic amendments in three long-term (23, 154, and 170 yrs, respectively) field experiments significantly increased mineral availability, particularly of short-range-ordered (SRO) phases. Two microcosm studies demonstrated that the presence of roots significantly increased mineral availability and promoted the formation of SRO phases. Mineral transformation experiments and isotopic labeling experiments provided direct evidence that citric acid, a major component of root exudates, promoted the formation of SRO minerals, and that SRO minerals acted as "nuclei" for C retention. Together, these findings indicate that soil organic amendments initialize a positive feedback loop by increasing mineral availability and promoting the formation of SRO minerals for further C binding, thereby possibly serving as a management tool for enhancing carbon storage in soils.
矿物结合是土壤碳（C）稳定的主要机制，而矿物对 C 结合的可用性对 C 储存具有至关重要的影响。然而，调节矿物可用性的机制仍不清楚。在这里，我们表明，在三个长期（分别为 23、154 和 170 年）田间试验中的三种有机改良剂显著增加了矿物的可用性，特别是对短程有序（SRO）相。两项微宇宙研究表明，根的存在显著增加了矿物的可用性并促进了 SRO 相的形成。矿物转化实验和同位素标记实验提供了直接证据，表明柠檬酸（根系分泌物的主要成分）促进了 SRO 矿物的形成，并且 SRO 矿物充当了 C 保留的“核”。总之，这些发现表明，土壤有机改良剂通过增加矿物的可用性并促进 SRO 矿物的形成来启动正反馈循环，从而可能成为增强土壤碳储存的管理工具。
