生物质炭引起的土壤碳激发效应与土壤理化特性的相关性

生物炭因含有丰富的惰性碳元素而被看作是一种极富应用前景的固碳材料，将其施入土壤后可以增加土壤稳定性碳库，减缓全球气候变化。前人研究表明，生物炭添加到土壤中后，将增加（正激发效应）或者减缓（负激发效应）土壤原有机碳的矿化速率。然而，生物炭对不同土壤的激发效应以及土壤性质与生物炭激发效应之间的关系还不明确。因此，本研究利用13C 稳定性同位素标记的小麦秸秆制作成生物炭，分别将等碳量的生物炭和标记秸秆添加到四种不同性质的土壤中，室内培养一年，测定生物炭及秸秆中的碳元素在不同土壤中的降解量及其对土壤原有机碳的激发效应量。研究结果表明：生物炭在黑土水稻土以及下位砂姜土水稻土中引发了显著的负激发效应，激发效应量分别为-284 mg/kg和-157 mg/kg，而在红壤水稻土以及低肥力红壤水稻土（长期定位不施肥的红壤水稻土）中引发正激发效应，激发效应量分别为33.3 mg/kg和58.0 mg/kg；秸秆在四种土壤中引发的激发效应量不同，均为正激发效应，正激发效应量远大于生物炭。生物炭激发效应量与土壤的Ec（r= -0.884）以及pH（r= -0.824）成极显著的负相关关系。生物炭-碳在不同土壤上的累积降解量存在显著差异，黑土水稻土中为15.6 mg/kg，红壤水稻土中为14.2 mg/kg，下位砂姜土以及低肥力红壤水稻土中相似，分别为10.4 mg/kg和9.92 mg/kg；秸秆-碳的累积降解量远大于生物炭-碳，其在低肥力红壤水稻土中的降解量显著低于其他三种土壤。生物炭添加在黑土水稻土中碳净损失量最低，下位砂姜土水稻土中次之，低肥力红壤水稻土中最高。研究表明，生物炭在土壤中的固碳效果不仅受到生物炭-碳自身降解速率的影响，还会受到生物炭引发的土壤碳激发效应量的影响。

Correlation Between Biochar-induced Carbon Priming Effect in Soils and Soil Physiochemical Properties

Biochar-induced priming effects were different between different soils, however the relationship between the priming effect and soil properties were still unclear. ¹³C-labelled biochar pyrolyzed from ¹³C-labelled wheat straw was incorporated into 4 kinds of soils with contrasting properties for one-year incubation in lab, additionally, equivalent carbon amount ¹³C labelled wheat straw was also conducted. Results showed that biochar induced significant negative priming effects in Mollisol paddy soil and Inceptisol paddy soil, and the priming amount were -284 mg/kg and -157 mg/kg, respectively, but in Ultisol paddy soil and low fertility Untisol paddy soil (long-term experiment plot without fertility amendment), biochar induced positive priming effects with 33.3 mg/kg and 58.0 mg/kg priming amount respectively; Wheat straw induced different positive priming effects in soils, and the positive priming amounts were higher than those of the biochar-induced. Biochar-induced priming effect was significantly negatively correlated with soil EC (r=-0.884) and soil pH (r=-0.824). After one-year incubation, and the cumulative biochar-carbon decomposition were 15.6 mg/kg in Mollisol paddy soil, 14.2 mg/kg in Untisol paddy soil, 10.4 mg/kg in Inceptisol paddy soil and 9.92 mg/kg in low fertility Untisol paddy soil; Straw-carbon cumulative decomposition was much higher than biochar-carbon, and it was the lowest in low fertility paddy soil than in other three soils. The calculated carbon net loss was the lowest in Mollisol paddy soil following by Inceptisol paddy soil, and low fertility Ultisol paddy soil was the highest. The study indicates that carbon sequestration effect of biochar is influenced not only by decomposition of biochar-carbon itself, but also by biochar-induced priming effect.