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以广西环江(石灰土)、湖南桃源(红壤)两个亚热带典型农田(旱地)长期定位试验为平台,采用碱性氧化铜-固相萃取-气相色谱法,分析两种长期施肥制度[化肥(NPK)、秸秆还田配施化肥(NPKS)]下土壤中木质素V、S、C等3类单体含量及组成的变化,并阐明影响旱地土壤中木质素积累的主要因子.结果表明:长期施用化肥(NPK)对石灰土木质素总量(SumVSC)无显著影响,而红壤木质素总量显著增加(55±1)%;秸秆还田配施化肥(NPKS)均显著增加了两种土壤木质素总含量(P<0.01),增加比例分别为(328±4)%、(456±9)%.长期施肥处理增加了红壤木质素单体C的比例,石灰土则表现为单体V的比例增加,表明农田土壤中木质素的转化具有单体特异性;长期施肥后木质素单体的酸醛比(Ac/Al)V和(Ac/Al)S均有所降低,其中石灰土高于红壤,说明石灰土的木质素分解矿化程度较红壤高.有机质、全氮与木质素单体含量无显著相关,而对木质素单体V、S、C组成有显著影响;木质素V、S和C类单体含量及组成均与土壤速效养分(碱解氮、速效磷、速效钾)显著相关(P<0.05),由此认为土壤速效养分是木质素积累特性的关键影响因子.
Two long-term fertilization systems were used, including long-term experiment on two typical subtropical farmland (dry land) in Huanjiang (lime soil) and Hunan Taoyuan (red soil), using alkaline copper oxide-solid phase extraction-gas chromatography NPK and NPKS, and clarified the main factors affecting the accumulation of lignin in dryland soil.The results showed that the content of lignin, (NPK) had no significant effect on SumVSC, but the total amount of lignin in red soil increased significantly (55 ± 1)%; and the ratio of straw returning to fertilizers (NPKS) increased significantly by two The total content of soil lignin (P <0.01) increased by (328 ± 4)% and (456 ± 9)%, respectively. Long-term fertilization increased the proportion of lignin C in red soil, The proportion of body V increased, indicating that the conversion of lignin in farmland soil was monomer-specific. After long-term fertilization, the ratio of Ac / Al V and Ac / Al S was decreased, Lime soil is higher than red soil, indicating that lime soil lignin decomposition mineralization degree higher than red soil organic matter, total nitrogen and lignin monomer content (P <0.05), but significantly affected the composition of V, S and C of lignin. The content and composition of V, S and C monomers were significantly correlated with available nutrients (available nitrogen, available phosphorus and available potassium) (P <0.05). Therefore, soil available nutrients are the key factors affecting the accumulation of lignin.