不同施量生物炭对土壤团聚体及其有机碳含量的影响

Effects of Different Biochar Application Rates on Soil Aggregates and Their Organic Carbon Contents

为评价施用生物炭对土壤有机碳(Soil organic carbon,SOC)稳定性和固碳(C)潜力的影响,通过C3源(种植大豆)暗棕壤施用C_(4)源(玉米秸秆)生物炭2年的盆栽试验,基于团聚体多级层次结构尺度,研究了施用6(BC6),12(BC12),24(BC24)t/hm^(2)生物炭对土壤以及不同粒径团聚体及其有机碳组分的影响,探讨不同施量生物炭对SOC的物理化学保护机制的影响。结果表明:与未添加生物炭处理相比,施用生物炭显著提高总SOC含量16.5%~32.4%,>2 mm大型大团聚体(LMA)及其闭蓄态微团聚体(LMIo和SMIo)质量比例,分别显著增加29.43%~53.30%和24.00%~35.86%,其SOC分别显著增加14.00%~38.69%和13.83%~34.87%;>2 mm和2~0.25 mm大团聚体(LMA和SMA)、0.25~0.053 mm游离微团聚体(MI)和未团聚的粉/黏粒(NA-SC)等组分中的矿物结合态SOC分别显著提高14.68%~15.96%,11.51%~17.59%,9.80%~20.55%和16.56%~64.21%;>2 mm和2~0.25 mm大团聚体中粗颗粒有机质(Particulate organic matter,POM)以及闭蓄态、游离态微团聚体中轻组的细POM均显著增加。另外,不同施量生物炭提高了各级水稳性团聚体δ^(13)C值,生物炭源-C在各级水稳性团聚体中的分配随团聚体粒径的增大而增加。因此,施用不同数量生物炭可促进土壤团聚体对SOC的物理化学保护,对提高SOC的数量与稳定性、促进团聚体的形成以及实现C封存都具有积极的影响。

To evaluate the effects of biochar application on the stability of soil organic carbon(SOC)and carbon sequestration potential,a two-year pot experiment was conducted by applying biochar derived from C_(4)(corn stalk)plant into the dark brown soil derived from C3(plating soybeans)plant,based on the structure scale of hierarchical aggregates.The effects of biochar addition at the rates of 6(BC6)12(BC12)and 24(BC24)t/hm^(2)soil,respectively,on the content of organic carbon(OC)in soil,aggregates and their density components were studied,and the effects of different application rates of biochar on the physicochemical protection mechanism of SOC were discussed.The results showed that compared with no biochar control,SOC content significantly increased by 16.5%-32.4%.The>2 mm large macroaggregates and their occluded microaggregates in the mass proportion markedly increased by 29.43%-53.30%and 24.00%-35.86%,respectively,and simultaneously,OC significantly increased by 14.00%-38.69%and 13.83%-34.87%,respectively.The mineral-associated organic C within macroaggregates(>2 and 2-0.25 mm),free microaggregates(0.25-0.053 mm)and nonaggregated silt/clay(<0.053 mm)were all significantly improved by 14.68%-15.96%,11.51%-17.59%,9.80%-20.55%and 16.56%-64.21%,respectively.The OC content of coarse particulate organic matter(POM)within>2 and 2-0.25 mm macroaggregates and fine POM in the light fraction within the occluded microaggregates and free microaggregates all significantly increased.In addition different rates of biochar application improved theδ^(13)C value of all size fraction of water-stable aggregates,the distribution of biochar-derived C increased with the increase of aggregates size.Therefore the application of different rates of biochar can promote the physical and chemical protection of soil aggregates to organic C,ans has a positive impact on the improvement of quantity and stability of SOC promoting the formation of aggregates and achieving sequestration.