Crop residue management effects on organic matter in paddy soils — The lignin component
Crop residue management effects on organic matter in paddy soils — The lignin component
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DOI：
10.1016/j.geoderma.2008.05.004
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发表时间：
2008-07
期刊：
影响因子：
6.1
通讯作者：
Andreas Bierke;K. Kaiser;G. Guggenberger
中科院分区：
文献类型：
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作者：
Andreas Bierke;K. Kaiser;G. Guggenberger
水稻集约化种植不仅增加了水稻产量，而且还增加了作物残留量。特别是，残渣中的木质素成分可能会由于氧气限制条件下的不完全分解而积聚在沉水系统中，如水稻土。在这里，我们研究了两个试验点(南京、长沙)和一个菲律宾试验点(洛斯巴尼奥斯、拉古纳)秸秆还田对水稻土有机质的短期和长期影响。测定了有机碳和总氮的含量，用~(13)C核磁共振谱表征了碱提物SOM的组成，用CuO氧化法测定了木质素的组成。结果表明，在南京和洛斯巴尼奥斯最近建立的试验中，有机碳、总氮和木质素衍生的总酚在加入作物残渣后没有显著变化。相比之下，在长沙的长期实验中，所有测试变量都有所增加。从1990年到2005年的16年间，“残留物掺入”样地的有机碳增加了41%，而“去除残留物”样地的有机碳增加了16%。‘残留物掺入’区的N-木质素衍生酚总量增加了约45%(‘残留物去除’区增加了12%)，有类似的趋势。在实验的初始阶段，处理木质素变化的参数发生了变化。这些变化与在通风种植系统中观察到的变化相当。在实验的后期阶段，木质素的组成没有进一步的变化。~(13)C核磁共振谱显示SOM组成基本不变，因此支持CuO氧化的结果。综上所述，作物残体在水稻土中的额外输入似乎仅仅导致了有机质的积累；木质素衍生酚类的较大比例反映了作物残体的输入。去除残留物和掺入残留物处理的木质素氧化变化程度相当，表明土壤系统可以应对残留物衍生木质素输入的增加。
Intensified rice cropping is not only increasing rice yields but also the amount of crop residue. In particular the lignin component of the residues may accumulate in submerged systems such as paddy soils due to incomplete decomposition under oxygen-limited conditions. Here, we examined the short and long-term effects of crop residue management on soil organic matter (SOM) in paddy soils of two experimental sites in China (Nanjing, Changsha) and one in the Philippines (Los Baños, Laguna). We determined organic C and total N, characterized the composition of alkaline-extractable SOM by13C NMR spectroscopy, and the lignin component by CuO oxidation. The results revealed no significant changes in organic C, total N and total lignin-derived phenols upon incorporation of crop residue at the recently established experiments at Nanjing and Los Baños. In contrast, all tested variables increased at the long-term experiment at Changsha. Within 16 years (1990 to 2005), the organic C increased by 41% in the ‘residue incorporated’ plots while at the ‘residue removed’ plots the increase was 16%. Similar trends were found for total N. Lignin-derived phenols in ‘residue incorporation’ plots increased about 45% (12% for ‘residue removed’ plots). Parameters addressing alteration of lignin changed at the initial stages of the experiments. These changes are comparable to those observed in aerated cropping systems. No further changes in the lignin composition occurred at later stages of the experiments. The13C NMR spectra revealed a largely unchanged SOM composition, thus supporting the results of the CuO oxidation. In summary, the additional input of crop residue in paddy soils seems to result in the mere accumulation of OM; the larger proportion of lignin-derived phenols reflects the input of crop residue. The comparable degree in oxidative alteration of lignin between ‘residue removed’ and ‘residue incorporated’ treatments indicates that the soil systems can cope with the increased residue-derived lignin input.