光照与黑暗培养对亚热带区稻田及旱地土壤有机碳及其活性组分的影响

农田土壤的固碳潜力对于理解陆地生态系统碳循环和气候变化至关重要.分别选取亚热带区4种典型稻田和旱地土壤,设置裸土光照和裸土黑暗处理,探讨土壤有机碳(SOC)及其活性组分(可溶性有机碳(DOC)和微生物生物量碳(MBC))对光照和黑暗条件的响应。结果表明,与培养前相比,培养80 d后,光照和黑暗培养下稻田及旱地土壤SOC含量差异不显著,这可能与土壤SOC含量变化是一个缓慢的过程有关.光照和黑暗培养均显著提高了土壤DOC含量(与培养前相比,光照和遮光培养平均分别提高73.37%和80.58%),而MBC显著降低(与培养前相比,光照和遮光培养平均分别降低35.58%和32.32%)。相关分析表明,培养后的土壤DOC含量与土壤粘粒含量呈极显著正相关性(P<0.01),而与土壤原有碳氮水平呈极显著负相关;土壤MBC则恰好相反,MBC与土壤粘粒含量呈极显著负相关,而与土壤原有碳氮水平呈极显著正相关.本研究表明,短期(80d)的光照和黑暗培养对稻田及旱地土壤SOC含量变化影响不大,而显著改变了有机碳活性组分(DOC和MBC)含量,进一步说明了土壤活性有机碳是土壤中活性化学组分,随环境条件变化表现出强烈的变化趋势。

Influences of Illumination and Unillumination Incubation on Soil Organic Carbon and Active Organic Carbon Content from Paddy and Upland Soil of Subtropical Regions

Carbon(C) sequestration capacity in agriculture eco-system plays a key role in C cycling in terrestrial eco-system and global climate change.A pot experiment with two treatments(illumination and unillumination) was conducted to investigate the responses of light condition on soil organic C(SOC) and active organic C nic C(DOC amd MBC) from eight typical subtropical soils,corresponding to four paddy and four upland soils,respectively.The results showed that there’s no significant difference observed between 80-day illumination and un-illumination incubation,compared with before incubation.This revealed that the changes of SOC content was a slow processed.However,DOC was increased by average of 73.37%,80.58% under illuminated and unilluminated condition,respectively.On the contrary,MBC decreased by the mean of 35.58%,32.32% under illumination and unillumination condition,respectively,in comparison with the beginning of incubation.Correlation analysis showed that DOC was significant positively(P<0.01) correlated with clay content but negatively correlated with native C and N level,however,MBC was significant negative(P<0.01) correlated with clay content and positive correlated with native C and N level.These results suggest that soil active organic carbon is the most important carbon pool in soil,due to its active characteristics and fast turnover,it also showed a strong variation tendency to environmental changes.