摘要:川西北高寒草原特殊的地理环境、气候条件以及过度人为放牧导致草地沙化问题突出。为了探讨不同生物质改良剂对高寒草地沙化土壤有机碳特征的影响，采用随机区组试验设计方法，设置3种生物质改良剂[秸秆类（JG）、菌渣类（JZ）、生物炭类（SWT）]，2个施用水平（6 t·hm-2和18 t·hm-2），以空白处理（CK）为对照，研究高寒草地沙化土壤总有机碳、活性有机碳和呼吸特征的变化。结果表明：1）施用生物质改良剂显著提高了土壤有机碳（TOC）、微生物量碳（MBC）和易氧化有机碳（EOC）含量，且提高效果随改良剂施用量的增加而增强。与CK相比，JG、JZ、SWT处理0~10 cm TOC含量分别平均提高60.66%、39.22%、34.99%，且JG处理显著高于JZ和SWT处理；MBC含量在0~10 cm则表现为JZ > JG > SWT > CK，且处理间差异达显著水平；EOC含量表现为JG处理最高，在0~10 cm、10~20 cm土层处分别比对照提高108.82%、79.26%。2）不同生物质改良剂处理中，EOC/TOC表现为JG > JZ > SWT > CK，MBC/TOC表现为JZ > JG > SWT > CK，且不同处理间差异显著。3）施用不同改良剂均显著提高了土壤呼吸速率，且随改良剂施用量的增加，土壤呼吸速率显著增加。与CK相比，施用6 t·hm-2的JG、JZ、SWT的土壤呼吸速率平均提高103.42%、86.31%、18.83%，JZ和JG处理的土壤呼吸速率显著高于SWT和CK处理。相关性分析表明，土壤水分与土壤呼吸速率呈显著正相关关系，TOC、MBC以及EOC与土壤呼吸速率呈极显著正相关关系。4）施入不同改良剂均显著提高了土壤呼吸总量、土壤微生物呼吸总量和净生态系统生产力（NEP值），均表现出较强的碳汇潜力，JG处理的NEP值较JZ和SWT处理分别显著提高56.45%和122.12%，且各处理间差异显著，说明秸秆改良剂具有较高的碳汇强度。该研究可为川西北藏区补充完善高寒草地沙化土壤制定科学有效的土壤碳调控管理措施提供依据。
关键词:高寒草地/
沙化土壤/
生物质改良剂/
土壤有机碳/
微生物量碳/
易氧化有机碳/
土壤呼吸/
碳平衡
Abstract:The special geographical environment, climatic conditions, and excessive artificial grazing in the alpine grassland of northwestern Sichuan have caused grassland desertification. To examine the effects of different biomass amendments on the soil organic carbon composition and respiration characteristics in alpine desertification grassland, we adopted a randomized block test design method and two factors field trials for setting biomass amendments and their application rates. The biomass amendments used were three kinds of straw (JG), slag (JZ), and biochar (SWT). The application rates were 6 t·hm-2 (JG1, JZ1, SWT1) and 18 t·hm-2 (JG3, JZ3, SWT3). We used blank treatment (CK) as a control to examine the effects of the different amendments on the total organic carbon, the activated organic carbon, and the respiratory characteristics in desertified soil. The findings demonstrated that:1) application of the biomass amendments significantly increased the contents of soil organic carbon (TOC), microbial biomass carbon (MBC), and easily oxidized organic carbon (EOC), which became more obvious as the amounts of amendments were increased. Compared with CK, the organic carbon in the 0-10 cm soil layer increased averagely by 60.66%, 39.22%, and 34.99% with JG, JZ and SWT treatments, respectively; the soil MBC content was expressed as JZ > JG > SWT in the 0-10 cm soil layer, and the difference among treatments were significant. EOC content was the highest in JG treatment; in the 0-10 cm and 10-20 cm soil layers, it was increased averagely by 108.82% and 79.26%, respectively, compared with CK. 2) Under different biomass amendments, EOC/TOC revealed that JG > JZ > SWT > CK, MBC/TOC revealed that JZ > JG > SWT > CK, and the differences among treatments were significant. 3) The application of different amendments increased the soil respiration rate significantly in proportion to the increased application rate of the amendment. Compared with CK, the soil respiration rates of JG1, JZ1, and SWT1 treatments increased by 103.42%, 86.31%, and 18.83%, respectively. The soil respiration rates were significantly higher under JZ and JG treatments compared with SWT and CK treatments. Correlation analysis revealed significant positive correlation of the soil respiration rate with soil water (P < 0.05), and significant positive correlations with organic carbon, MBC, and EOC (P < 0.01). 4) The application of different biomass amendments significantly increased soil respiration, soil microbial respiration, and net ecosystem productivity (NEP), both of which showed strong carbon sink potential. Under JG treatment, the NEP value was significantly higher than that under JZ and SWT treatments, by 56.45% and 122.12%, respectively, and there were significant differences among treatments. These findings suggested that the straw improver had higher carbon sink strength. This study can provide a basis for the development of scientific and effective soil carbon regulation and management measures for improving alpine grassland desertification soil in the northwestern Sichuan Basin in China.
Key words:Alpine grassland/
Desertification soil/
Biomass amendment/
Soil organic carbon/
Microbial biomass carbon/
Easily oxidized organic carbon/
Soil respiration/
Carbon budget
PDF全文下载地址:
http://www.ecoagri.ac.cn/article/exportPdf?id=844e6e5d-836f-4b21-99fd-f1928757ca37
