不同施肥管理对农田土壤木质素积累的影响

The Effect of Fertilization Managements on Lignin Accumulation in An Arable Soil

施肥是维持和增加农田土壤有机质的重要管理措施，其中，稳定性土壤有机碳库与长期碳截获密切相关。土壤中木质素对微生物具有高度的抗性，根据其水解性单体的变化，可指示土壤木质素动态、稳定性及其氧化程度。因此，研究利用肥料与肥力长期定位实验，采用碱性氧化铜氧化-气相色谱方法，根据土壤中各木质素单体含量和侧链基团的变化，探讨不同施肥处理对农田黑土中木质素积累和稳定性碳库的影响。实验结果表明，和对照处理（不施肥，cK）相比，化肥施用对0—20cm的土壤木质素积累并未产生显著影响，但显著增加了20～40cm土壤的木质素含量；长期施用有机肥使0—20em和20～40cm的土壤中木质素的含量分别提高了197％～301％和306％-382％，均与施肥量正相关，同时使0—20cm的木质素单体的酸醛比显著降低。相对于土壤有机碳来说，长期施用有机肥使0～20cm和20。40em的木质素来源碳的相对含量分别提高了151％～187％和267％～285％，但是化肥施加仅对20。40cm土壤有机碳中木质素来源碳含量产生显著影响。土壤木质素的积累特征和氧化程度在不同施肥处理间的差异表明，化肥施用增加了植物来源木质素的输入，也同时加速了木质素在耕层的周转，所以长期施用化肥并未导致木质素的积累；来源于有机肥的活性碳源的输入降低了木质素的微生物降解作用，有利于稳定性碳的积累，增加了土壤有机碳的可持续利用能力。

Fertilization is an effective management to maintain and increase soil organic carbon （SOC） level in agroecosystems. Stable SOC pool is considered to be closely associated with long-term C sequestration. Lignin is highly recalcitrant for microorganisms, thus its hydrolyzed monomers can be used as the main biomarker for stable SOC pool, to indicate the origin and degradation of soil organic matter. In this research, an alkaline CuO oxidation and gas chromatographic method was performed for the quantification and the oxidation evaluation of lignin in arable soil experienced different fertilization practices in the northeastern of China. The results showed that the chemical fertilizer application did not exhibit significant influence on the soil lignin accumulation in 0 - 20 cm depth, compared to control （CK）, but increased the content of lignin in 20 - 40 cm soil significantly. Long-term organic fertilization supply increased the content of soil lignin by 197 - 301% in 0 - 20 cm and 306 - 382% in 20 - 40 cm layer, respectively, which was positively correlated with the amount of manure application. The lignin-derived C normalized to SOC increased 151 ~ 187% and 267 ~ 285%, correspondingly. The ratios of carboxylic acid to aldehyde in lignin monomers after manure applications were significantly lower than CK treatment. The difference of accumulation dynamics and oxidation degree of lignin among fertilization treatments suggested that chemical fertilization increased the lignin input but simultaneously accelerated the lignin turnover. Large amount of available C derived from manure deduced the lignin microbial decomposition, benefiting the accumulation of stable SOC and improving the sustainability of SOC.