Soil aeration is a crucial factor that regulates crop residue decomposition, and the chemical composition of decomposing crop residues may change the forms and availability of soil nutrients, such as N and P. However, to date, differences in the chemical composition of crop straw residues after incorporation into soil and during its decomposition under anaerobic vs. aerobic conditions have not been well documented. The objective of the present study was to assess changes in the C-containing functional groups of wheat straw residue during its decomposition in anaerobic and aerobic environments. A 12-month incubation experiment was carried out to investigate the temporal variations of mass, carbon, and nitrogen loss, as well as changes in the chemical composition of wheat (Triticum aestivum L) straw residues under anaerobic and aerobic conditions by measuring C-containing functional groups using solid state nuclear magnetic resonance (NMR) spectroscopy. The residual mass, carbon content, and nitrogen content of the straw residue sharply declined during the initial 3 months, and then slowly decreased during the last incubation period from 3 to 12 months. The decomposition rate constant (k) for mass loss under aerobic conditions (0.022 d-1) was higher than that under anaerobic conditions (0.014 d-1). The residual mass percentage of cellulose and hemicellulose in the wheat straw gradually declined, whereas that of lignin gradually increased during the entire 12-month incubation period. The NMR spectra of C-containing functional groups in the decomposing straw under both aerobic and anaerobic conditions were similar at the beginning of the incubation as well as at 1 month, 6 months, and 12 months. The main alterations in C-containing functional groups during the decomposition of wheat straw were a decrease in the relative abundances of O-alkyl C and an increase in the relative abundances of alkyl C, aromatic C and COO/N-C = O functional groups. The NMR signals of alkyl C and aromatic C in decomposing wheat straw residues under anaerobic condition were higher than those under aerobic conditions. The higher mass percentages of lignin and the higher signals of aromatic C and alkyl C functional groups in decomposing wheat residues under anaerobic conditions than under aerobic conditions were due to the slower decomposition rates of aryl C and alkyl C in wheat straw residues under anaerobic conditions.
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机译：土壤通气是调节农作物残渣分解的关键因素，分解农作物残渣的化学成分可能会改变土壤养分（如氮和磷）的形式和有效性。但是，迄今为止，农作物秸秆残渣的化学成分存在差异掺入土壤后以及在厌氧与好氧条件下的分解过程中，尚未有充分的文献记载。本研究的目的是评估麦秸秆在厌氧和好氧环境中分解过程中含碳官能团的变化。进行了为期12个月的温育实验，通过测量含C量来研究厌氧和有氧条件下小麦（Triticum aestivum L）秸秆残留物的质量，碳和氮损失的时间变化以及化学成分的变化。固态核磁共振（NMR）光谱分析官能团。秸秆残留物的残留质量，碳含量和氮含量在最初的3个月中急剧下降，然后在3到12个月的最后孵化期间缓慢下降。有氧条件下（0.022 d -1 ）的质量损失分解速率常数（k）高于无氧条件下的（0.014 d -1 ）。在整个培养期的12个月中，麦秸中纤维素和半纤维素的残留质量百分比逐渐下降，而木质素的残留质量百分比逐渐增加。在有氧和无氧条件下，分解秸秆中含碳官能团的NMR光谱在培养开始时以及在1个月，6个月和12个月时都相似。小麦秸秆分解过程中含碳官能团的主要变化是O-烷基C的相对丰度下降，烷基C，芳族C和COO / N-C = O官能团的相对丰度增加。厌氧条件下分解麦草渣中烷基碳和芳族碳的NMR信号高于有氧条件。与厌氧条件相比，厌氧条件下分解小麦残渣中木质素的质量百分比较高，芳香族C和烷基C官能团的信号较高，这是由于厌氧条件下麦草残渣中芳基C和烷基C的分解速率较慢。
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