生物炭配施沼液对土壤团聚体及其有机碳分布的影响

The Effect of Biochar Amendment and Slurry Application on Soil Aggregation and Organic Carbon Distribution

【目的】探究生物炭与沼液配施的最优组合,为农田合理施肥提供科学依据。【方法】基于3 a(2017―2019年)田间定位试验,设置CK、单施生物炭(12 t/hm^(2))、3个水平沼液(沼液∶水分别为1∶6、1∶4和1∶2)和生物炭分别与3个水平沼液配施,共计8个处理,利用湿筛法测定了土壤团聚体分布和有机碳质量分数。【结果】生物炭和沼液配施能有效提高>0.25 mm粒级的土壤水稳性团聚体质量分数,较CK增加幅度为13.0%~36.3%;各施肥处理不同程度地提高了土壤团聚体的平均重量直径(MWD)和几何平均直径(GMD),增加幅度分别为9.8%~39.3%和10.0%~37.5%,沼液配比为1∶4时生物炭配施沼液对团聚体MWD值和GMD值影响最大;施肥处理各粒级团聚体有机碳质量分数显著高于CK,生物炭配施沼液的效果要优于单施生物炭或沼液处理。有机碳与>0.25 mm粒级的团聚体质量分数、MWD值和GMD值均呈极显著正相关关系。同时,各施肥处理降低了土壤体积质量,最大降幅为6.7%。添加生物炭和猪场沼液对提高土壤团聚体稳定性和改善土壤结构有积极作用。【结论】从提高土壤质量和资源高效利用方面考虑,12 t/hm^(2)的生物炭,配施1∶4沼液对该地区效果最佳。

【Background and objective】Biogas slurry and biochar have been increasingly used to amend soils for different purposes ranging from as soil conditioner to fertilizer. While their influence on soil properties has been well documented, their impact on soil aggregation and the consequence for soil organic distribution was poorly understood. The purpose of this paper is to fill this knowledge gap.【Method】The experiment was conducted in the field with no biochar amendment taken as the control(CK). For each biochar amendment(B), there were three slurry(originated from pig manure) applications at volumetric ratios(water∶slurry): 1∶6(BS1), 1∶4(BS2) and 1∶2(BS3), respectively. Soil samples were taken from each treatment at the end of the experiment, and the proportions of aggregates of different sizes in the range of >5 mm, 2~5, 1~2, 0.25~1 mm and <0.25 mm were determined by wet sieving method. Organic carbon in each group of aggregates was measured using standard method.【Result】Amending the soil with biochar in combination with biogas slurry irrigation improved the proportion of >0.25 mm aggregates significantly by 13.0%~36.3%, compared with the CK. The mean weight diameter(MWD) and geometric diameter(GMD) of the aggregates in all treatments were both higher than that in the CK, increasing by 9.8%~39.3%(MWD) and 10.0%~37.5%(GMD), respectively. Both MWD and GMD peaked when the slurry application was 1∶4. All treatments also increased soil organic carbon in aggregates of different sizes significantly,beneficial to soil quality. Significant positive correlations were found among organic carbon content in different aggregates, macro-aggregates(>0.25 mm), MWD and GMD(P<0.01). The treatments reduced soil bulk density significantly, with the highest decrease being 6.7% in B+BS3. All these showed that applying biochar and pig manure biogas slurry to soil has a significantly positive effect on soil aggregation, improving soil structure and carbon sequestration.【Conclusion】 Biochar amendment and biogas slurry irrigation improved soil quality. For all treatments we compared, the optimal application of biochar and the slurry was 12 t/hm^(2) and 1∶4, respectively.