生物炭施用5a后对桂北桉树人工林土壤有机碳组分的影响

Effects of Biochar Application on Soil Organic Carbon Component in Eucalyptus Plantations After Five Years in Northern Guangxi

研究生物炭不同施用量施用5 a后桉树人工林土壤有机碳组分的变化特征,明确生物炭施用下土壤的固碳潜力,为桉树林业废弃物生物炭的土壤改良效应提供科学依据.基于2017年建立的桉树人工林生物炭中长期定位试验,以桉树人工林废弃枝条为原料,在500℃条件下厌氧制备生物炭,选取CK(0%)、T1(0.5%)、T2(1.0%)、T3(2%)、T4(4%)和T5(6%)这6个处理,一次性施用生物炭5 a后测定不同处理下有机碳组分含量特征.结果表明:(1)与对照相比,土壤有机碳及其组分随生物炭施用量的增加而增大,且在T4或T5达到最大值,土壤有机碳、可溶性有机碳、易氧化态有机碳、颗粒有机碳、微生物生物量碳和碳储量分别增加了101.62%、67.46%、143.03%、164.78%、110.88%和41.73%.(2)随着生物炭施用量的增加,各生物炭处理土壤轻组有机碳和重组有机碳含量在0~10、10~20、20~30 cm土层的增幅分别为41.41%~140.63%、9.26%~87.04%、-19.54%~106.90%和15.32%~78.99%、15.72%~75.25%、89.49%~148.64%.0~30 cm土层土壤轻组有机碳和重组有机碳含量的平均值亦呈现增大的趋势,土壤碳库中以较稳定的重组有机碳为主.(3)土壤有机碳、碳储量和有机碳组分含量均随着土层的加深而减小.总体上,生物炭施用5 a显著增加了土壤有机碳和碳组分含量,有利于提高土壤固碳能力和土壤稳定性碳库,生物炭施用是提升桉树林土壤质量的有效措施.研究结果可为林业废弃物资源化利用和桉树人工林土壤肥力提升提供参考依据.

To investigate the effects of biochar(BC)addition on soil organic carbon(SOC)contents and its fractions under different biochar applications,Eucalyptus waste twigs in Northern Guangxi were used to produce BC at 500℃.Additionally,we sought to clarify and define the carbon sequestration potential of soil and provide a basis for the preparation of biochar from Eucalyptus forest wastes and soil improvement.In a long-term positioning test of biochar application from 1997,six different treatments were selected:0(CK),0.5%(T1),1%(T2),2%(T3),4%(T4),and 6%(T5).The contents of SOC,light fraction organic carbon(LFOC),heavy fraction organic carbon(HFOC),easily oxidized organic carbon(EOC),dissolved organic carbon(DOC),particulate organic carbon(POC),microbial biomass carbon(MBC),and carbon stock(CS)following the different treatments were measured.The results showed that:①compared to that in the control,biochar application induced an increase in each soil organic carbon fraction with increasing application rate and reached a maximum under the T4 or T5 treatments;with the increase in biochar application,the contents of SOC,DOC,EOC,POC,MBC,and CS increased significantly by 101.62%,67.46%,143.03%,164.78%,110.88%,and 41.73%,respectively.②The contents of LFOC and HFOC in the 0-10,10-20,and 20-30 cm soil layers increased significantly by 41.41%-140.63%,9.26%-87.04%,and-19.54%-106.90% and 15.32%-78.99%,15.72%-75.25%,and 89.49%-148.64%,respectively,with the increase in biochar application.The average contents of LFOC and HFOC in the 0-30 cm soil layer also increased gradually.The soil carbon pool of the Eucalyptus forest was dominated by a relatively stable heavy fraction organic carbon.③The contents of carbon stock,soil organic carbon,and its fractions decreased with the increase in soil depth.In conclusion,the application of forestry waste biochar for five years could significantly increase the content of SOC and its components,thereby increasing soil organic carbon activity.Therefore,increasing the amount of biochar was an effective measure to enhance the carbon storage,soil stable carbon pool,and soil quality of the Eucalyptus plantation field.This study provides a reference for the resource utilization of forestry waste and improvements in soil fertility of Eucalyptus plantations.