施用沼液对紫花苜蓿种植土壤有机碳、氮组分影响研究

为明确沼液替代氮肥对种植紫花苜蓿石灰性土壤有机碳、氮组分的影响，开展田间试验，设置不施肥，常规施用化肥氮，基于化肥氮20%用量的沼液＋80%化肥氮，基于化肥氮50%用量的沼液＋50%化肥氮，基于常规施用化肥氮100%、200%用量的沼液共6个处理，分析比较各处理对土壤有机碳、氮组分影响。结果表明：随沼液配施比例的提高，土壤酸解氨基酸态氮、酸解总氮含量逐渐增加，与单施化肥相比，100%和200%沼液施用处理下土壤氨基酸态氮、酸解总氮含量分别显著提高13.93%~37.21%和8.22%~21.71%；20%~50%沼液施用利于提高土壤非酸解态氮含量；与100%沼液施用相比，200%沼液施用处理土壤酸解未知态氮和全氮含量分别下降9.01%~37.00%和0.89%~7.87%；沼液施用提高了土壤酸解氮组分尤其是酸解氨基酸态氮的比例。全氮与酸解总氮、氨基糖态氮和未知态氮含量呈极显著正相关关系。土壤腐殖酸、富里酸、游离腐殖酸和有机碳含量随沼液配施比例的提高而提高；与单施化肥相比，沼液100%和200%施用处理显著提高富里酸含量，沼液50%施用处理显著提高胡敏酸含量，胡富比随沼液施用比例提高呈下降趋势；有机碳与腐殖酸、游离腐殖酸、残渣碳、富里酸含量呈极显著正相关关系。综上所述，本研究条件下基于常规施用化肥氮100%用量的沼液更有利于土壤有机碳、氮组分含量的累积。

Effects of biogas slurry application on organic carbon and nitrogen components of alfalfa cultivation soil

A field trial was used to determine the effects of biogas slurry on organic carbon and nitrogen components of calcareous soil planted with alfalfa. The study included treatments of control without fertilizer, conventional fertilizer nitrogen, 20% fertilizer nitrogen content of biogas slurry+80% fertilizer nitrogen, 50% fertilizer nitrogen content of biogas slurry+50% fertilizer nitrogen and biogas slurry based on conventional application of fertilizer nitrogen of 100% and 200%. The results showed that the contents of amino acid nitrogen and total acid hydrolysis nitrogen in soil increased with the increase of the combined application ratio of biogas slurry. Compared with single application, the contents of amino acid nitrogen and total nitrogen were significantly increased by 13.93%~37.21% and 8.22%~21.71%, respectively. Application of 20%~50% biogas slurry was beneficial to the increase of soil non\|acidolysis nitrogen. Compared with 100% biogas slurry application, the contents of unknown nitrogen and total nitrogen in 200% biogas slurry application decreased by 9.01%~37.00% and 0.89%~7.87%, respectively. The application of biogas slurry was beneficial to the increase of soil acidolysis nitrogen, especially amino acid nitrogen. Total nitrogen was positively correlated with total nitrogen, amino sugar nitrogen and unknown nitrogen. The contents of humic acid, fulvic acid, free humic acid and organic carbon in soil increased with the increase of biogas mixture ratio. Compared with single fertilizer application, 100% and 200% application of biogas slurry significantly increased the fulvic acid content, 50% application of biogas slurry significantly increased the humic acid content, and the ratio of humic acid to fulvic acid decreased with the increase of biogas slurry application ratio. Organic carbon was positively correlated with humic acid, free humic acid, residual carbon and fulvic acid. In summary, under the conditions of this study, it is suggested that when the amount of biogas slurry is 100% nitrogen fertilizer, it is more conducive to the accumulation of soil organic carbon and nitrogen components.