稻草及其制备的生物质炭对土壤团聚体有机碳的影响

EFFECTS OF APPLICATION OF RICE STRAW AND STRAW BIOCHAR ON ORGANIC CARBON IN SOIL AGGREGATES

向土壤中添加生物质炭已被认为是改善土壤质量，增加碳吸存的有效措施。通过模拟实验，利用同位素δ13 C标记技术，研究稻草及其制备的生物质炭添加对土壤团聚体有机碳的影响。结果表明：稻草和生物质炭对土壤团聚体中新形成碳和原有机碳的影响截然不同。培养112 d，来自稻草或生物质炭的新碳主要进入到中团聚体（50 - 250 μm）中，比例为70.3% - 75.3%。与对照土壤相比，稻草添加显著促进了大团聚体（250 - 2 000 μm）原有机碳的分解（p 〈0.05），但对中团聚体和微团聚体（〈50 μm）原有机碳的影响并不明显，而生物质炭添加（SB250和SB350）则对大团聚体和中团聚体原有机碳没有显著影响，但SB250处理（土壤中加入250℃热解制备的生物质炭）显著抑制了微团聚体原有机碳的分解（p 〈0.05），而SB350处理（土壤中加入350℃热解制备的生物质炭）的则无影响。对于同一粒级团聚体，稻草与生物质炭处理的区别，主要体现在新碳分配上，而对原有机碳的影响并不显著。

Applying biochar to soil has been suggested as a practice both to improve soil quality and to increase carbon sequestration of the soil. In this study effects of amendment of rice straw and straw biochar on organic carbon in aggregates various in fraction were investigated using the stable carbon isotope technique. 13C-labeled rice straw and straw biochar （prepared at 250℃ or 350℃） was mixed separately with red soil （Ferrosols） for incubation in the experiment. Results show that the effects of rice straw and biochar on fresh carbon and native soil organic carbon were completely different. After 112 days of incubation, the fresh carbon supplied by straw or biochar was mainly found in the 50 - 250 μm fraction of soil aggregates, making up 70.3% - 75.3% of the total. Compared with CK, amendment of rice straw significantly stimulated decomposition of the native organic carbon in the 250 - 2 000 μm fraction of soil aggregates, but had no such significant effect in the 50 - 250 μm and 〈50 μm fractions of aggregates, and the amendment of biochar （either SB250 or SB350） did not affect much decomposition of the native organic carbon in the 250 - 2 000 μm and 50 - 250 μm fractions of aggregates, but the amendment of biochar SB250 did significantly inhibit decomposition of the native organic carbon in the 〈50 μm fraction of aggregates, however, no such effect was found with the amendment of biochar SB350. The effects of rice straw and straw biochar on carbon in soil aggregates of the same size fraction differed mainly in distribution of fresh carbon, rather than native soil organic carbon.