摘要
土壤微生物生物量碳(MBC)和溶解有机碳(DOC)是土壤有机碳的活性组分,能够较快反映土壤环境变化。以14C标记葡萄糖和稻草为底物,室内培养法研究了相同含水量(45%WHC)条件下,红壤旱地和稻田土壤活性有机碳对外源有机底物的响应。结果表明,土壤微生物能迅速吸收利用葡萄糖和稻草中的DOC组分,而使土壤MBC含量在短时间(前5d)内出现最大值。添加葡萄糖和稻草处理,旱地土壤MBC峰值分别高于对照69.4%和55.1%,稻田土壤高于对照10.2%和10.5%。整个培养期(100d)内,添加葡萄糖和稻草处理旱地土壤MBC的平均含量分别高于对照82.1%和41.5%(P<0.05);而稻田土壤MBC在培养前期(0～60d),分别高于对照8.8%和5.1%(P<0.05),60d后与对照差异不显著。葡萄糖和稻草的添加对旱地土壤总DOC含量没有显著影响(0～2d除外),但可明显提高稻田土壤总DOC含量(增幅为12.8%～26.0%)。100d内,2个土壤中14C标记MBC(14C-MBC)占总量的比例为4.5%～47.4%,14C标记DOC(14C-DOC)为4.0%～12.7%。说明在土壤含水量为45%WHC条件下,有机底物的添加对旱地土壤MBC的影响大于稻田土壤,但对DOC的影响则反之。同位素示踪表明,土壤有机质本身是DOC和MBC的主要来源。
Soil microbial biomass carbon （ MBC）- and dissolved organic carbon （DOC） are the main components of soil active organic carbon, and can rapidly respond to the changes of soil environment. In this study, ^14C-labeled glucose and rice straw were added to an upland soil and a paddy soil sampled from the red earth region of China, and the effects of the amendment on the active organic carbon in the two soils were investigated with laboratory incubation under 45% water holding capacity （WHC）. The results showed that the DOC derived from the exogenous organic substrates was assimilated immediately by soil microbes, and the MBC reached the maximum during the first 5 days of incubation. With the amendment of glucose and rice straw, the peak value of MBC in upland soil and paddy soil was 69. 4% and 55.1%, and 10. 2% and 10. 5% higher than the control, respectively. In the upland soil added with glucose and straw, the averaze content of MBC in the whole incubation period （100 d） had a significant increase （P 〈 0. 05 ）, being 82. 1% and 41.5% higher than the control, respectively; while in the paddy soil added with these organic substrates, the MBC had an increase of 8.8% and 5.1% during 0-60 d, but was similar to the control thereafter. The amendment of glucose and rice straw had no significant effects on the total DOC content in upland soil except in the first 2 days of incubation, but increased it by 12.8%-26. 0% in paddy soil. The percentages of ^14C-labeled MBC to total MBC and of ^14C-labeled DOC to the total DOC in the two soils were 4. 5%-47.4% and 4. 0%--12. 7%, respectively. It was suggested that under the condition of 45% WHC, the effects of the amendment of organic substrates on MBC were larger in upland soil than in paddy soil ; while those on DOC were in adverse. ^14C tracer showed that soil organic matter itself was the main source of MBC and DOC.
出处
《生态学杂志》
CAS
CSCD
北大核心
2008年第12期2178-2183,共6页
Chinese Journal of Ecology
基金
中国科学院知识创新工程项目(KZCX2-YW-408和KZCX2-YW-423)
国家自然科学基金资助项目(40771116和40671104)
关键词
旱地
稻田
土壤微生物生物量碳
溶解有机碳
upland soil
paddy soil
soil microbial biomass carbon
dissolved organic carbon.
