生物炭还田对植烟土壤活性有机碳及酶活性的影响

为探索不同来源的生物炭及其还田方式对连作植烟土壤的改良效果,以四川盐源红壤为研究对象,通过田间试验研究了不同生物炭类型(玉米秸秆生物炭YM、油菜秸秆生物炭YC)配合不同还田方式(条施、穴施、条施+穴施)下,土壤有机碳组分和土壤酶活性在烤烟不同生育期的变化特征。结果表明,生物炭类型和还田方式显著改变了土壤总有机碳(TOC)含量,与CK(不添加生物炭)相比,生物炭处理的土壤TOC含量增加了6.9%~39.7%,其中油菜生物炭穴施还田的效果最佳。生物炭提高了土壤活性有机碳库和颗粒态有机碳含量,其中油菜生物炭处理的活性有机碳平均含量显著高于玉米生物炭,颗粒态有机碳含量则相反;与CK相比,玉米生物炭和油菜生物炭穴施还田提高了土壤可溶性有机碳含量,分别显著增加了25.3%~36.4%和33.3%~51.3%;油菜生物炭穴施还田的烤烟旺长期土壤微生物量碳、易氧化有机碳和颗粒态有机碳含量最高,较CK分别增加了34.6%、28.9%和38.3%。土壤蔗糖酶、蛋白酶活性总体受生物炭类型和还田方式的显著影响,与CK相比,油菜生物炭穴施还田的土壤蔗糖酶活性显著提高了24.1%~30.6%;玉米生物炭对烤烟现蕾期和成熟期土壤脲酶、蛋白酶活性提升效果总体优于油菜生物炭。综上,生物炭还田总体增加了植烟土壤有机碳库含量和酶活性,其中油菜生物炭穴施还田方式对土壤活性有机碳库、蔗糖酶活性的提升效果较佳。本研究结果为植烟土壤保育技术和生物炭在烟草生产的应用提供了科学依据和指导实践。

Effect of Biochar Returning on Labile Organic Carbon and Enzyme Activity in Tobacco-Growing Soil

To explore the effects of different biochar types and biochar application methods on the tobacco-growing soil, a field experiment was conducted in the red soil areas in Yanyuan country, Sichuan province. The effects of different biochar types (i.e., maize straw biochar (YM), rape straw biochar (YC)) and biochar application methods (i.e., band application, hole application, band application combined with hole application) on the changes of soil organic carbon fractions and enzyme activities during the growth of tobacco were studied. Results showed that biochar types and application methods significantly affected the soil total organic carbon (TOC) contents. Compared with control (no biochar addition), biochar application increased the soil TOC contents by 6.9%~39.7%, especially for the rape straw biochar applied in the hole. The application of biochar increased the contents of soil labile organic carbon fractions (LOC, the sum of dissolved organic carbon (DOC), microbial biomass carbon (MBC) and readily oxidizable carbon (ROC)) and particulate organic carbon (POC). The average contents of LOC in soil amended with were significantly higher than those with YM, but the opposite result was found for POC. Additionally, biochar types and application methods significantly influenced the contents of soil LOC fractions. Soil DOC contents in YM and YC increased by 25.3%~36.4% and 33.3%~51.3% relative to the control, respectively (P<0.05). The highest contents of MBC, ROC and POC at the vigorous stage were obtained in the YC treated soil via the hole application method, which increased by 34.6%, 28.9% and 38.3% compared with the control, respectively. Soil sucrase and protease activities were significantly influenced by biochar types and biochar application methods. Compared with the control, higher activity of soil sucrase was observed in the YC treated soil, especially for the hole application, which increased by 24.1%~30.6%. YM application increased the soil urease and peroxidase activities in the squaring and maturity stages, and the promotion degrees were better than YC. Overall, biochar applications increased the contents of soil organic carbon fractions and sucrase activities. Biochar derived from rape straw and applied in the hole could better increase soil LOC fractions and surcase activity than others in this study. These results provide a conservation technique in tobacco growing soil and a scientific basis and practicing guidance for the application of biochar.