Institute of Resource, Ecosystem and Environment of Agriculture, Nanjing Agricultural University, 1 Weigang, Nanjing, 210095, PR China; Department of Soil Science, Nanjing Agricultural University, 1 Weigang, Nanjing, 210095, PR China; Jiangsu Collaborative Innovation Center for Solid Organic Waste Resource Utilization, Nanjing Agricultural University, 1 Weigang, Nanjing, 210095, China.
Institute of Resource, Ecosystem and Environment of Agriculture, Nanjing Agricultural University, 1 Weigang, Nanjing, 210095, PR China; Department of Soil Science, Nanjing Agricultural University, 1 Weigang, Nanjing, 210095, PR China.
J Environ Manage. 2021 May 1;285:112104. doi: 10.1016/j.jenvman.2021.112104. Epub 2021 Feb 17.
While biochar enhanced carbon sequestration and stability of soil organic matter (SOM), changes in organic molecular composition in biochar-amended soils had been poorly addressed. In this study, molecular composition changes of a paddy topsoil 2 years following amendments at 10 t ha OC equivalent with untreated (CS), manured (CM) and charred (CB) maize straw were compared to no amendment (CK). Topsoil SOM was sequentially extracted with ultrapure water (UWE), solvent (TSE), base hydrolysis (BHY) and CuO oxidation (CUO) and molecular compounds in these extracted fractions were detected quantitatively by GC/MS. Compared to CK, SOC content was increased respectively by 12% under CS and CM, and by 36% under CB. Fraction abundance both of UWE and CUO was increased but that of TSE unchanged under CS and CM, while that of BHY unchanged under CS but increased by > 60% under CM and CB, respectively. Under CB relative to CS and CM, abundance of TSE and BHY fractions was greatly increased but that of UWE and CUO unchanged. Specifically, abundances of water-soluble monosaccharides, low molecular weight organic acids and lignin-derived phenols, especially cinnamyl-based monomers, were all enhanced under CS, but abundances of n-alkanols, fatty acids in free lipids and di-acids and hydroxyl fatty acids in bound lipids were decreased under both CS and CM. In contrast, CB amendment increased abundances of n-alkanols, alkanes and sterols in free lipids while enhanced molecular and functional group diversity of UWE and TSE fractions. Overall, short-term crop residue amendment altered the abundance and molecular diversity of OM mainly associated with short-lived UWE and labile TSE fractions and biochar enhanced preservation of plant derived molecules mainly in lipids. Thus, returning crop residue as biochar could be a sustainable approach to enhance not only SOM pool but molecular diversity also in agricultural soils.
尽管生物炭增强了土壤有机碳（SOM）的固存和稳定性，但生物炭添加土壤中有机分子组成的变化尚未得到充分解决。在这项研究中，比较了在 10 t ha OC 当量下用未处理（CS）、施肥（CM）和碳化（CB）玉米秸秆处理两年后稻田表土的有机分子组成变化，与不添加（CK）的情况相比。用超纯水（UWE）、溶剂（TSE）、碱水解（BHY）和氧化铜氧化（CUO）依次提取表土 SOM，并用 GC/MS 定量检测这些提取部分中的分子化合物。与 CK 相比，CS 和 CM 下 SOC 含量分别增加了 12%和 36%，而 CB 下增加了 36%。CS 和 CM 下 UWE 和 CUO 部分的丰度增加，但 TSE 部分不变，而 CS 下 BHY 部分不变，但 CM 和 CB 下分别增加了>60%。与 CS 和 CM 相比，CB 下 TSE 和 BHY 部分的丰度大大增加，但 UWE 和 CUO 部分不变。具体而言，CS 下水溶性单糖、低分子量有机酸和木质素衍生酚，特别是肉桂基单体的丰度均增加，但 CS 和 CM 下的 n-烷醇、游离脂质中的脂肪酸以及结合脂质中的二酸和羟基脂肪酸的丰度均降低。相比之下，CB 处理增加了游离脂质中 n-烷醇、烷烃和甾醇的丰度，同时增强了 UWE 和 TSE 部分的分子和官能团多样性。总体而言，短期作物残茬添加改变了主要与短暂 UWE 和不稳定 TSE 部分相关的有机物质的丰度和分子多样性，而生物炭增强了植物衍生分子在脂质中的保存。因此，将作物残茬作为生物炭返回农业土壤不仅可以增加 SOM 库，还可以增加分子多样性，这是一种可持续的方法。
