Anhui Province Key Laboratory of Farmland Conservation and Pollution Prevention, School of Resources and Environment, Anhui Agricultural University, Hefei 230036, China.
Anhui Province Key Laboratory of Farmland Conservation and Pollution Prevention, School of Resources and Environment, Anhui Agricultural University, Hefei 230036, China; State Key Lab of Tea Plant Biology and Utilization, Anhui Agricultural University, Hefei 230036, China.
Sci Total Environ. 2018 Jun 1;625:1065-1073. doi: 10.1016/j.scitotenv.2017.12.293. Epub 2018 Jan 12.
Crop straw incorporation is a useful approach for increasing the quantity and changing the chemical composition of soil organic matter (SOM). This process is influenced by soil aeration. The present study investigated the stability of whole SOM, particulate organic matter (POM) and mineral-associated organic matter (MinOM) fractions with wheat straw amendment under aerobic and anaerobic conditions over a 12-month incubation period. Solid-state nuclear magnetic resonance and Fourier transform infrared spectroscopy were used to analyze the chemical composition of whole SOM, POM and MinOM fractions. The decomposition rate of wheat straw was lower under anaerobic than under aerobic conditions (0.014 vs. 0.020day). Wheat straw incorporation increased the original soil organic carbon content (7.4g kg) under both aerobic (up to 10.2g·kg) and anaerobic (up to 10.3g·kg) conditions, but the content of mineral-associated organic carbon (MinOC) under aerobic condition (7.0g·kg) was significantly larger than that under anaerobic condition (4.9g·kg). The proportion of alkyl carbon (C) in SOM, POM and MinOM fractions was greater under anaerobic than under aerobic conditions, while the opposite was true for the proportion of O-alkyl C of SOM and POM and MinOM fractions. A/O-A indices (i.e., the ratio of alkyl C to O-alkyl C) of whole SOM, POM and MinOM were higher under anaerobic than under aerobic conditions. We conclude that wheat straw incorporation resulted in the enrichment of alkyl C in the POM and MinOM fractions under anaerobic conditions, and thus improved the stability of SOM. In this way, the decomposition of crop residue influenced SOM structural chemistry at the molecular level.
秸秆还田是增加土壤有机质（SOM）数量和改变其化学组成的有效方法。这一过程受土壤通气性的影响。本研究通过 12 个月的好气和厌气培养，调查了添加小麦秸秆后，SOM、颗粒有机物质（POM）和矿物结合有机物质（MinOM）各组分的稳定性。采用固态核磁共振和傅里叶变换红外光谱分析了各组分的化学组成。与好气条件相比，厌气条件下小麦秸秆的分解率较低（0.014 比 0.020 天）。好气（最高增加到 10.2g·kg）和厌气（最高增加到 10.3g·kg）条件下添加小麦秸秆均增加了原始土壤有机碳含量（7.4g·kg），但好气条件下的矿物结合有机碳（MinOC）含量（7.0g·kg）显著大于厌气条件下的含量（4.9g·kg）。SOM、POM 和 MinOM 各组分中的烷基碳（C）比例在厌气条件下大于好气条件下，而 SOM 和 POM 及 MinOM 各组分中的 O-烷基 C 比例则相反。SOM、POM 和 MinOM 的 A/O-A 指数（即烷基 C 与 O-烷基 C 的比值）在厌气条件下高于好气条件。我们得出结论，小麦秸秆的添加在厌气条件下导致 POM 和 MinOM 各组分中烷基 C 的富集，从而提高了 SOM 的稳定性。这样，作物残体的分解就从分子水平上影响了 SOM 的结构化学。
