Department of Biotechnology, University of Verona, Strada Le Grazie 15, 37134, Verona, Italy.
Instituto de Ciencias Agrarias, Consejo Superior de Investigaciones Científicas, Serrano 115 bis, 28006, Madrid, Spain.
J Environ Manage. 2023 Sep 1;341:118092. doi: 10.1016/j.jenvman.2023.118092. Epub 2023 May 9.
The sustainability of Mediterranean croplands is threatened by climate warming and rainfall reduction. The use of biochar as an amendment represents a tool to store organic carbon (C) in soil. The vulnerability of soil organic C (SOC) to the joint effects of climate change and biochar application needs to be better understood by investigating its main pools. Here, we evaluated the effects of partial rain exclusion (∼30%) and temperature increase (∼2 °C), combined with biochar amendment, on the distribution of soil organic matter (SOM) into particulate organic matter (POM) and the mineral-associated organic matter (MAOM). A set of indices suggested an increase in thermal stability in response to biochar addition in both POM and MAOM fractions. The MAOM fraction, compared to the POM, was particularly enriched in labile substances. Data from micro-Raman spectroscopy suggested that the POM fraction contained biochar particles with a more ordered structure, whereas the structural order decreased in the MAOM fraction, especially after climate manipulation. Crystalline Fe oxides (hematite) and a mix of ferrihydrite and hematite were detected in the POM and in the MAOM fraction, respectively, of the unamended plots under climate manipulation, but not under ambient conditions. Conversely, in the amended soil, climate manipulation did not induce changes in Fe speciation. Our work underlines the importance of discretely taking into account responses of both MAOM and POM to better understand the mechanistic drivers of SOC storage and dynamics.
地中海农田的可持续性受到气候变暖和降雨量减少的威胁。生物炭的使用作为一种改良剂，可以将有机碳（C）储存在土壤中。需要通过研究其主要库来更好地了解土壤有机碳（SOC）对气候变化和生物炭应用的联合效应的脆弱性。在这里，我们评估了部分降雨排除（约 30%）和温度升高（约 2°C）以及生物炭添加对土壤有机质（SOM）分配到颗粒有机质（POM）和矿物结合有机质（MAOM）的影响。一组指标表明，生物炭添加后，POM 和 MAOM 两个部分的热稳定性都有所提高。与 POM 相比，MAOM 部分特别富含不稳定物质。微拉曼光谱数据分析表明，POM 部分含有结构更有序的生物炭颗粒，而 MAOM 部分的结构有序性在气候操作后降低，尤其是在气候操作后。在未受气候影响的对照条件下，POM 和 MAOM 部分中均检测到结晶态 Fe 氧化物（赤铁矿）和水铁矿与赤铁矿的混合物，但在环境条件下未检测到。相反，在添加生物炭的土壤中，气候操作不会引起 Fe 形态的变化。我们的研究强调了分别考虑 MAOM 和 POM 响应的重要性，以更好地了解 SOC 储存和动态的机制驱动因素。
