生物炭配施沼液对渗出液电导率、全氮含量及土壤理化性质的影响

Effects of combined application of biochar and biogas slurry on percolate electrical conductivity,total nitrogen and soil physical and chemical properties

为增加沼液中养分在土壤中的滞留量,提高沼液利用效率,采用室内土柱试验,设置不同沼液配比(沼液∶水(体积比)分别为1∶4、1∶6、1∶8)、生物炭混掺量(0.0%、0.5%、1.0%、2.0%(土壤质量分数))和生物炭混掺厚度(5、10、15、20 cm),探讨生物炭配施沼液对土柱渗出液电导率、土壤全氮、土壤容重、土壤水稳定性团聚体、土壤总孔隙度、pH值和土壤有机质的影响。结果表明:沼液配比为1∶8时,生物炭配施沼液对全氮淋失无明显作用,沼液配比为1∶6时,渗出液全氮淋失幅度为34.49%~66.79%,沼液配比为1∶4时,渗出液全氮淋失幅度为4.17%~71.67%,即生物炭配施沼液能有效地提高土壤中的全氮含量。随生物炭混掺量的增加,土壤>0.25 mm水稳定性团聚体含量、土壤总孔隙度和土壤有机质含量均有所增加,而随沼液配比的减小均逐渐降低,土壤>0.25 mm水稳定性团聚体较CK增加幅度为8.47%~31.99%,土壤总孔隙度增加幅度为0.76%~3.72%,土壤有机质增加幅度为4.83%~37.17%;土壤容重随土壤中生物炭混掺量和沼液配比的增大而逐渐减小,降低幅度为2.22%~8.15%,表明生物炭配施沼液有益于土壤理化性质的改善。

In order to increase the retention of nutrients in the soil and improve the utilization efficiency of biogas slurry,an indoor soil-column experiment was carried out.Different biogas slurry ratios(1∶4,1∶6,and 1∶8 of biogas slurry∶water,volume ratio),biochar mixing rates(0.0%,0.5%,1.0%,and 2.0%of soil mass fraction),and biochar mixing thickness(5,10,15 cm,and 20 cm)were set up to study the effect of biochar combined with biogas slurry on soil column exudate.Soil physical and chemical properties including electrical conductivity,total nitrogen(N),bulk density,water stability aggregates,total porosity,pH value,and organic matter were studied.The results showed that when biogas slurry ratio was at 1∶8,biochar combined with biogas slurry had no significant effect on total N leaching.When biogas slurry ratio was at 1∶6,the leaching range of total N in exudate was 34.49%~66.79%.When biogas slurry ratio was at 1∶4,the leaching range of total N in exudate was 4.17%~71.67%,that indicated that biochar combined with biogas slurry effectively improved the total N content in soil.With increasing biochar ratio,the soil had more water stable aggregate>0.25 mm,higher soil total porosity and soil organic matter with a range of CK<0.5%<1.0%<2.0%.With decreasing biogas slurry ratio in an order of 1∶4>1∶6>1∶8,soil water stable aggregate>0.25 mm increased by 8.47%~31.99%,soil total porosity increased by 0.76%~3.72%,and soil organic matter increased by 4.83%~37.17%.Soil bulk density increased with increasing the proportion of biochar and biogas slurry in the soil with a decreasing range of 2.22%~8.15%,which showed that biochar with biogas slurry improved the physical and chemical properties of the soil.