生物质炭施用对不同深度稻田土壤有机碳矿化的影响

本文旨在揭示生物质炭施用下不同深度稻田土壤有机碳矿化特征的变化,为提高稻田土壤生物质炭施用下的固碳效应提供参考。以太湖地区施用生物质炭2 a后的水稻土为研究对象,采集了7个不同土壤深度的土壤样品,通过室内培养试验,分析了生物质炭施用下不同深度土壤有机碳分布及矿化特征。结果表明,生物质炭仅显著增加了表层(0～10 cm)土壤总有机碳含量,而对深层土壤无显著影响。然而,与对照相比,施用生物质炭显著降低了土壤0～40 cm有机碳矿化强度,0～10、10～20、20～30、30～40 cm土层的降幅分别为23.74%、37.57%、37.62%和15.95%,并降低了10～40 cm土层的微生物生物量碳和0～40 cm土层微生物代谢熵,同时表层(0～10 cm)土壤微生物生物量碳显著增加11.3%,而以上各指标在40 cm以下土层未因生物质炭添加而产生显著变化。因此,生物质炭在2 a尺度上提高了稻田土壤0～40 cm有机碳的稳定性,有助于增加深层土壤固碳潜力。

Effects of biochar application on soil organic carbon mineralization at different depths in paddy soil

This study aimed to clarify the effect of biochar on soil organic carbon mineralization characteristics of paddy soil at different depths and to provide a scientific basis for assessing the carbon sequestration effects of biochar in paddy soil. Soil samples were collected at seven different depths in a rice-cropping field located in Taihu Lake Region, which had received one dose of biochar two years ago. A laboratory experiment was conducted to analyze the organic carbon distribution and mineralization characteristics of the soil. The results showed that biochar application significantly increased the total organic carbon content in the surface layer(0~10 cm); however, it had no significant effect on the total organic carbon content in the layers below 10 cm. Compared with the control treatment, the biochar application significantly decreased the soil organic carbon mineralization intensity within the upper 40 cm layer. The decrease rate was 23.74%, 37.57%, 37.62%, and 15.95% for the 0~10 cm, 10~20 cm, 20~30 cm, and 30~40 cm layers, respectively. Biochar application significantly decreased the microbial biomass carbon in the 10~40 cm soil layer and the microbial metabolic quotient in the 0~40 cm soil layer, whereas the soil microbial biomass carbon in the surface layer(0~10 cm)was significantly increased by 11.3% in the biochar treatment. Below 40 cm layer, there was no significant change in any of the above indicators for biochar treatment. The results suggest that biochar application can improve the soil organic carbon stability within the 0~40 cm layer in paddy soil on a two-year scale, which is beneficial for the carbon sequestration potential in deep layers of the soil profile.