紫色土壤有机碳活性组分对生物炭施用量的响应

Soil Organic Carbon of Purple Soil as Affected by Different Application of Biochar

土壤有机碳(SOC)是土壤最重要的组成部分,土壤活性有机碳是引起土壤碳库变化的关键,为研究在不同施用量生物炭还田下土壤有机碳及其活性组分的影响,本试验在重庆国家紫色土肥力与肥料效益长期监测基地测定了无物料还田(CK)、生物炭还田(8 000 kg·hm-2,BC)、0.5倍生物炭还田(4 000 kg·hm-2,0.5 BC)、2倍生物炭还田(16 000 kg·hm-2,2BC)配施化肥处理下的紫色土丘陵区油菜/玉米轮作制中土壤有机碳及活性组分含量.结果表明:(1)施用生物炭可以显著提高土壤有机碳的含量(P<0.05),在一定范围内,生物炭的施用量与土壤有机碳含量成正比.适量的生物炭施入土壤后,土壤微生物量碳(SMBC)含量上升,但0.5BC和2BC处理下土壤微生物量碳反而减少.生物炭不同施入量均可提高土壤可溶性碳(DOC)和土壤易氧化碳(ROC)的含量,其中0.5BC处理的含量最高,分别为198.83 g·kg-1和4.86 g·kg-1.(2)生物炭的施用均显著降低了土壤微生物熵和ROC/SOC,其中0.5BC处理最低,分别较CK处理下降了20.45%和4.11%,而2BC处理最高.0.5BC和BC处理均能提高DOC/SOC,且0.5BC处理显著高于BC处理.总体上,虽然生物炭还田微生物活性较低,但土壤有机碳及其稳定性较高,有利于土壤有机碳积累,促进土壤固碳.同时适量的生物炭还田可以持续稳定增长土壤有机碳含量,少量生物炭0.5BC处理还田可提高土壤中可溶性有机碳和易氧化有机碳含量.

Soil organic carbon（SOC） is the most important part of the soil carbon pool and soil labile organic carbon is a key indicator of changes in the soil carbon pool. In order to study changes in SOC and its labile components with different biochar additions to soil,a field experiment was conducted at Chongqing National Purple Soil Fertility and Fertilizer Efficiency of Long-Term Monitoring Station.Different amounts of biochar（0 kg·hm^-2,CK; 4 000 kg·hm^-2,0. 5 BC; 8 000 kg·hm^-2,BC; 16 000 kg·hm^-2,2 BC） combined with fertilizer were applied to purple soil in this hilly area. SOC and soil labile carbon content were determined for purple soil rapemaize rotation systems. Results showed that：（1） Application of biochar can significantly improve SOC content; within a certain range,the amount of added biochar is correlated with SOC content. The content of soil microbial biomass carbon（SMBC） increased with application of 8 000 kg·hm^-2 biochar,but decreased with application of 4 000 and 16 000 kg·hm^-2. The content of dissolved organic carbon（DOC） and readily oxidized carbon（ROC） in soil increased with different amounts of biochar; the highest DOC（198. 83 g·kg^-1） and ROC（4. 86 g·kg^-1） were obtained under low biochar addition treatments.（2） The application of biochar significantly decreases the ratio of soil ROC to SOC and microbial entropy. The ratio of soil ROC to SOC and microbial entropy of 0. 5 BC treatment are 20. 45% and 4. 11%,respectively,lower than for CK. Moreover,0. 5 BC and BC treatments can significantly improve the ratio of soil DOC to SOC. In summary,biochar addition in soil leads to low soil microbial activity but higher soil stability. An appropriate biochar treatment can stimulate accumulation of SOC,and 0. 5 BC treatment can improve soil DOC and ROC.