生物质炭施加对新成水稻土碳组分及其分解的影响

Effects of Biochar Amendment on Soil Carbon Fractions and Their Decomposition in a North-Subtropical Paddy Field

将玉米芯热解炭化的生物质炭施加于长江沉积物新成土上发育的稻田土壤中,1 a后采集土壤并进行土壤碳分组及土壤培养;基于生物质炭与土壤的碳同位素丰度差异,量化生物质炭来源的有机质在土壤组分中的分布,分析施用生物质炭对土壤碳组分及其培养过程中分解动态的影响。结果表明,施用生物质炭可显著增加各级团聚体的有机碳含量,大部分(76%~90%)生物质炭以游离态形式存在于大团聚体(>250μm)和微团聚体(>50~250μm)外,少部分与微团聚体或<20μm土壤矿质较紧密地结合。添加的生物质炭未促进土壤团聚体的形成。土壤中生物质炭自身的分解很弱,但不同程度地促进了原有土壤碳的分解。该试验初步证实,生物质炭单独施用未明显促进新成土上发育的稻田土壤有机碳的稳定,反之短期内可能加速土壤原有有机碳的分解。

Corncob-made biochar(C4)was amended to a paddy field which was newly developed from the Yangtze River sediment.After one-year biochar amendment the soil was fractionated to investigate the effects of biochar amendment on soil carbon fractions,as well as the carbon decomposition of such fractions during incubation.The distribution of biochar in soil fractions was quantified based on the different carbon isotope abundances between biochar and native soil organic carbon(nSOC,C3).The results indicate that biochar amendment significantly enhanced the organic matter content of aggregates at all size levels.76%-90%of biochar existed as free particles in the macroaggregate(>250μm)and microaggregate(>50-250μm)fractions;only a minor proportion of biochar showed relatively tight interactions with soil aggregates or<20μm mineral particles.These suggest that biochar amendment had not enhanced the formation of soil aggregates.Biochar itself decomposed extremely slowly during incubation of various soil fractions,but its amendment promoted the decomposition of nSOC.To conclude,the application of biochar alone did not significantly promote the soil carbon stabilization of entisols,but instead may accelerate the soil carbon decomposition in the short term.