生物炭对紫色土坡耕地侵蚀性耕层土壤有机碳的影响

Effects of Biochar on Soil Organic Carbon of Eroded Cultivated Layer of Slope Farmland in Purple Hilly Area

土壤有机碳是陆地生态系统最大的碳库,不仅是耕地土壤质量评价的核心指标,也是全球碳循环的重要组成部分.为研究耕层土壤有机碳对土壤侵蚀和管理措施交互作用的响应特征,以三峡库区典型紫色土坡耕地侵蚀性耕层土壤为研究对象,采用铲土侵蚀模拟试验小区,建立5种侵蚀程度的坡耕地原位试验,以不施肥(CK)为对照措施,设置单施化肥(F)和生物炭配施化肥(BF)两种恢复性管理措施,研究土壤有机碳含量在不同侵蚀程度和管理措施下的差异,分析土壤有机碳沿耕层剖面的变化特征及年际变化趋势.结果表明:1BF措施能显著提升紫色土坡耕地耕层有机碳含量,BF措施平均较CK和F措施提升90.25%和23.84%的有机碳;土壤侵蚀显著降低CK措施土壤有机碳12.25%~27.74%,不同侵蚀程度下有机碳含量的剖面分布差异不显著.2坡耕地表层(0~10 cm)土壤有机碳含量最高,且BF和F两种措施对表层有机碳含量提升效果也最明显,分别为120.59%和66.90%.3经过连续3 a的定位试验,坡耕地耕层土壤有机碳含量发生了显著变化,在CK措施下,有机碳年均损失12.52%;而在BF措施下,有机碳年均提升9.31%.4不同土层有机碳与土壤理化性质的相关性不同,土层越深,有机碳与各理化性质的相关性越弱.生物炭配施化肥措施可作为一种紫色土坡耕地侵蚀性耕层改良和侵蚀土壤肥力提升的重要措施.结果可为坡耕地合理耕层调控途径和土壤肥力提升提供基础参数.

Soil organic carbon(SOC)is the largest carbon pool in the terrestrial ecosystem.It is not only the core index of cultivated land soil quality evaluation but also an important part of the global carbon cycle.In order to understand the response characteristics of SOC in the cultivated layer to the interaction of soil erosion and management measures,the eroded cultivated layer of typical purple soil slope farmland in the Three Gorges Reservoir area was the research object.The in-situ tests of five erosion degrees on sloping farmland were established using the shovel erosion simulation test method;taking no fertilizer(CK)as a control measure,two types of restorative management measures were set up,namely chemical fertilizer(F)and biochar+chemical fertilizer(BF),to clarify the differences in SOC content under different erosion degrees and management measures and to analyze the variation characteristics and interannual variation trend of SOC along the cultivated-layer profile.The results showed that:1 BF significantly increased the soil organic carbon content in the cultivated layer of purple soil slope farmland;the SOC of BF was 90.25%and 23.84%higher than that of CK and F on average,respectively.Soil erosion significantly reduced the content of SOC(12.25%-27.74%)under CK measures,but there was no significant difference in the profile distribution of SOC under different erosion degrees.2 The SOC content in the surface layer(0-10 cm)of slope farmland was the highest,and the two measures had the most obvious effect on improving the SOC contents,which were 120.59%and 66.90%,respectively.3 After three consecutive years of experiments,the SOC content in the cultivated-layer of slope farmland changed significantly.Under CK,the average annual loss of SOC was 12.52%,whereas under BF,the average annual increase in SOC content was 9.31%.4 The correlation between SOC and soil physical and chemical properties was different in the various soil layers;the deeper the soil layer was,the weaker the correlation was.Therefore,biochar combined with chemical fertilizer(BF)was an important management measure to improve the erosive cultivated layer and enhance soil fertility for slope farmland in the purple hilly area.The results of this study can provide basic parameters for the rational regulation of cultivated layers and the improvement of soil fertility.