灌溉模式对保护地土壤可溶性有机碳与微生物量碳的影响#br#

 【目的】研究沟灌、渗灌、滴灌3种灌溉模式下,保护地土壤可溶性有机碳和微生物量碳在剖面中的分布特征。【方法】灌溉模式设沟灌、渗灌、滴灌3种,进行长达10年的长期定位灌溉试验。对长期定位灌溉试验保护地分层采集土壤样品,测定土壤总有机碳、可溶性有机碳、微生物量碳含量,分析其剖面分布特征。【结果】土壤总有机碳、可溶性有机碳和微生物碳含量均呈表层土壤最高、随土层深度增加而降低的分布趋势;但灌溉模式间差异明显,土壤总有机碳含量在0—10 cm、80—100 cm土层为沟灌＞渗灌＞滴灌,10—80 cm土层为渗灌＞沟灌＞滴灌;在0—100 cm剖面各层,可溶性有机碳含量均为沟灌＞滴灌＞渗灌,微生物量碳为滴灌＞沟灌＞渗灌。可溶性有机碳、微生物量碳占总有机碳的比率分别在4.98%—12.87%和1.48%—2.82%之间,其占总有机碳的比率均为滴灌＞沟灌＞渗灌。土壤可溶性有机碳、微生物量碳与土壤总有机碳含量呈显著的正相关关系。【结论】沟灌有利于土壤总有机碳、水溶性有机碳的积累,滴灌有利于微生物生物量碳的增加;渗灌相比较而言最不利于土壤有机质积累,不仅总有机碳含量低且水溶性含量占总有机碳的比例小。

Effect of Different Irrigation Patterns on Soil Dissolved Organic Carbon and Microbial Biomass Carbon in Protected Field

[Objective] The objective of this study was to research the distribution characteristics in the profile of dissolved organic carbon (DOC), microbial biomass carbon (MBC) in protected field under three irrigation patterns(subsurface irrigation, drip irrigation and furrow irrigation). [Method] The modes of irrigation are subsurface irrigation, drip irrigation and furrow irrigation. The same irrigation experiments were conducted for ten years. Soil samples at different depths within 0-100 cm were collected and the contents of soil total organic carbon (TOC), dissolved organic carbon (DOC), microbial biomass carbon (MBC) and their profile distribution were determined. [Result] The results showed that the content of soil total organic carbon, dissolved organic carbon, and microbial biomass carbon were all showed the biggest amount in the soil surface and their content increased with layers' depth, but there were significant differences within irrigation methods. Soil total organic carbon content in 0-10 cm and 80-100 cm soil layers were furrow irrigation > subsurface irrigation > drip irrigation and in 10-80 cm soil layers was subsurface irrigation>furrow irrigation>drip irrigation. In 0-100 cm profile layers, DOC content showed furrow irrigation>drip irrigation> subsurface irrigation. MBC content showed drip irrigation >furrow irrigation >subsurface irrigation. The content of DOC and MBC accounted for 4.98%-12.87% and 1.48%-2.82% of the total organic carbon, respectively. Their ratios were all showed drip irrigation >furrow irrigation>subsurface irrigation. There were significant positive correlation between the content of soil dissolved organic carbon, the microbial biomass carbon and the soil total organic carbon content. [Conclusion] Furrow irrigation is conducive to accumulation of SOC and DOC; drip irrigation is conducive to an increase in MBC; subsurface irrigation is the least conducive to theaccumulation of soil organic matter comparison, not only the content of TOC is low but also the content of DOC in the ratio of TOC is small.