Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, the Chinese Academy of Sciences, Changsha, 410125, P.R. China.
Southern Regional Collaborative Innovation Center for Grain and Oil Crops in China, Hunan Agricultural University, Changsha, 410128, P.R. China.
Sci Rep. 2018 Jan 26;8(1):1633. doi: 10.1038/s41598-018-20134-5.
Incorporation of crop residues is essential to enhance soil organic matter in arable ecosystems. Here, we monitored the dynamics of cellulose and lignin, the most abundant constituents of plant residues, and their relationships with enzyme activities, microbial gene abundances and soil properties after 13-year long-term and one-year short-term crop straw incorporation into upland and upland-paddy soils in a field-based experiment. Lignin, rather than cellulose, accumulated in both soils following straw incorporation. Cellulose was almost completely converted into non-cellulose forms within 6 and 3 months after straw incorporation into upland and upland-paddy rotation soils, respectively. Whereas, lignin accumulated at the rate of 129 and 137 mg kg yr within 13 years' straw incorporation in upland and upland-paddy rotation, respectively. The predominance of recalcitrant vanillyl monomers in upland-paddy rotation indicated a high stability of lignin. Structural equation models revealed that the key factor driving cellulose and lignin dynamics was available nitrogen, followed by enzymes activities (cellobiohydrolases and laccases) and functional genes abundances (cbhI and laccase-like) as mediated by soil pH. Our findings highlighted that upland might have higher carbon sequestration rate, whereas upland-paddy rotation system was more beneficial for accumulation of recalcitrant organic fractions under crop residue incorporation.
将作物残体纳入是提高旱地生态系统土壤有机质的关键。在这里，我们监测了纤维素和木质素（植物残体中最丰富的成分）的动态及其与酶活性、微生物基因丰度和土壤性质的关系，这些变化是在长达 13 年的长期和 1 年的短期作物秸秆纳入旱地和旱地稻田土壤的田间实验中观察到的。在秸秆纳入后，两种土壤中的木质素而非纤维素积累。纤维素在秸秆纳入旱地和旱地稻田轮作土壤后 6 个月和 3 个月内几乎完全转化为非纤维素形式，而木质素在 13 年内分别以 129 和 137 mg kg yr 的速率在旱地和旱地稻田轮作中积累。旱地稻田轮作中香草基单体的优势表明木质素具有较高的稳定性。结构方程模型表明，驱动纤维素和木质素动态的关键因素是可利用氮，其次是酶活性（纤维二糖水解酶和漆酶）和功能基因丰度（cbhI 和漆酶样），这些因素受土壤 pH 值的影响。我们的研究结果表明，旱地可能具有更高的碳固存率，而旱地稻田轮作系统在作物残体纳入下更有利于难降解有机物质的积累。
