中国农业科学 ›› 2014, Vol. 47 ›› Issue (9): 1764-1773.doi: 10.3864/j.issn.0578-1752.2014.09.011

• 土壤肥料·节水灌溉·农业生态环境 • 上一篇    下一篇

灌溉对农田温室效应贡献及土壤碳储量影响研究进展

 齐玉春1, 郭树芳1, 2, 董云社1, 彭琴1, 贾军强1, 2, 曹丛丛1, 2, 孙良杰1, 2, 闫钟清1, 2, 贺云龙1, 2   

  1. 1、中国科学院地理科学与资源研究所,北京 100101;
    2、中国科学院大学,北京 100049
  • 收稿日期:2013-12-16 出版日期:2014-05-01 发布日期:2014-02-28
  • 作者简介:齐玉春,Tel:010-64889320;E-mail:qiyc@ igsnrr. ac.cn
  • 基金资助:

    农业部公益性行业科研专项(201203012-6)、国家自然科学基金项目(41330528,41373084,41203054)

Advances in Research on the Effects of Irrigation on the Greenhouse Gases Emission and Soil Carbon Sequestration in Agro-ecosystem

 QI  Yu-Chun-1, GUO  Shu-Fang-1, 2 , DONG  Yun-She-1, PENG  Qin-1, JIA  Jun-Qiang-1, 2 , CAO  Cong-Cong-1, 2 , SUN  Liang-Jie-1, 2 , YAN  Zhong-Qing-1, 2 , HE  Yun-Long-1, 2   

  1. 1、Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101;
    2、Graduate University of Chinese Academy of Sciences, Beijing 100049
  • Received:2013-12-16 Online:2014-05-01 Published:2014-02-28

摘要: 农田碳库是全球碳库最活跃的部分,对管理措施变化的响应十分敏感。灌溉技术作为中国旱作农业的重要管理措施,其变化势必会对农田温室效应贡献及土壤碳固存能力产生重要影响,但相关试验数据及机理研究迄今仍十分缺乏。文章综述了灌溉对农田土壤呼吸及其不同组分、氧化亚氮(N2O)与甲烷(CH4)源汇通量以及农田土壤碳储量变化的定量影响,比较了上述参数变化对不同灌溉方式、灌溉量、灌溉频率、灌溉年限以及灌溉水质等的差异响应,剖析了可能的影响机制。分析表明:(1)灌溉通常将增加土壤的碳排放,但土壤呼吸与灌溉量间并非线性关系。在水分亏缺条件下,土壤呼吸与灌溉量呈现正相关,而过量灌溉则会降低土壤呼吸;灌溉影响土壤呼吸的温度敏感性(Q10),Q10与灌溉量之间呈抛物线关系,漫灌方式下土壤呼吸的温度敏感性高于滴灌;不同灌溉方式下土壤呼吸不同组分的贡献率及其对水分变化的响应存在较大差异,灌溉对根系呼吸的影响较对土壤微生物呼吸的影响更为显著,滴灌条件下根系呼吸对土壤呼吸的贡献率显著大于漫灌;灌溉水质与灌溉深度显著影响土壤温室气体释放总量,开展充分的市政污水处理能够为国家和地区换取更多的碳排放信用。(2)水分管理是减缓农田N2O与CH4排放的重要措施,水分状况对N2O与CH4的产生过程与排放途径均存在重要影响;水分管理对CH4和N2O排放的影响往往存在明显的消长关系,采用全球增温潜势(GWPs)等综合性评价指标才能更加准确与全面地反映灌溉及其不同方式所带来的农田温室效应贡献变化。(3)水分变化对土壤有机碳存在增加、降低或不显著等多种可能影响。不同气候、土壤类型下表层有机碳含量变化对灌溉的响应存在明显不同,灌溉在相对干旱地区对土壤有机碳的增加效应更为显著;不同组分有机碳对灌溉方式变化响应的敏感度以及响应方向存在差异,对于某种灌溉方式影响效应的评价须从农业节水、增加土壤有机碳储量以及提高活性有机碳利用率等多角度进行综合分析。迄今为止,灌溉对土壤主要温室气体排放及土壤有机碳储量的影响效应仍存在较大不确定性,今后应加强不同灌溉方式之间的对比研究,尤其是灌溉方式改变后土壤温室气体排放空间差异性的变化;重点关注灌溉及其方式变化对温室气体综合增温潜势以及生态系统碳源汇功能的影响;加强不同灌溉方式的长期与短期效应的比较;深化灌溉驱动农田温室效应变化的微生物学驱动机制的研究等。

关键词: 灌溉 , 农田生态系统 , 温室气体 , 土壤碳储量 , 研究进展

Abstract: Agricultural carbon (C) pool is one of the most active parts in global terrestrial ecosystem C pool and is very sensitive to change in management measures. As an important means for dry farming in China to get high yield, irrigation and its change in patterns certainly will have a significant impact on the ecosystem C budget and its atmospheric greenhouse effect, but the relative data and corresponding mechanism analysis are rarely known. This paper reviews research progresses in the quantitative impacts of irrigation on soil respiration and its different components, the fluxes of nitrous oxide and methane as well as soil C storage, and compares the differential responses of the above-mentioned processes to different irrigation patterns, amounts, frequencies, lasting periods and irrigation water quality, etc. The results indicate that irrigation generally will increase soil C emission, but the relationship between irrigation quota and soil carbon dioxide (CO2) effluxes is nonlinear. Water additions stimulate soil CO2 emission when soil is under water deficit condition, whereas excessive irrigation would decrease soil respiration rates. Irrigation increases the sensitivity of soil respiration to temperature change (Q10), and the response of Q10 to the irrigation amounts can describe as a parabola. The Q10 values under drip irrigation are larger than those under flood irrigation. There is a great difference in the response of different respiration components to the change of soil water under different irrigation methods, and the effect of irrigation on root respiration is more significant than on soil microbial respiration. The ratios of root respiration contribution to soil respiration under drip irrigation are much larger than those under flood irrigation. Irrigation water quality and irrigation depth also have an important impact on total emission amount of greenhouse gases, and full municipal wastewater treatment can obtain much more carbon emission credits for countries and regions. Water management is one of the important measures that mitigate the emissions of nitrous oxide (N2O) and methane (CH4). Both the emission amount and the emission pathway of N2O and CH4 are significantly affected by the soil water condition. There usually exists marked trade-off relationship between CH4 effluxes and N2O effluxes when soil moisture changes, so the comprehensive evaluation indicators such as global warming potentials (GWPs) are more conducive to reflect the actual change in greenhouse effect contribution of agricultural soil exactly. There exist various possibilities in the effect of irrigation on soil organic C (SOC) pool, such as increase, decrease, or no significant changes, and the responses of SOC to irrigation also vary a lot under different climate and soil conditions. In general, the stimulated effects of irrigation on SOC are more significant in relatively dry regions than in humid regions. Meanwhile, SOC in different forms often shows different response sensitivities and variation trends to irrigation. The effect evaluation of irrigation measures should be considered from the multiple perspectives of water-saving, increasing SOC pool and enhancing the utilization efficiency of liable organic C. To sum up, there still exists large uncertainties in the effects of irrigation on soil greenhouse gas emission and SOC in agro-ecosystem up to now. The future study should be focused on following contents: (1) to strengthen the comparison study of different irrigation patterns, especially the study on the spatial differences of greenhouse gases emission under different irrigation patterns; (2) to pay more attention to the comprehensive effect of different greenhouse gases and the ecosystem carbon budget; (3) to develop in-situ field research for both long period and short period; (4) to probe into the microbiology driving mechanism of irrigation on farmland greenhouse effect and soil C sequestration.

Key words: irrigation , agro-ecosystem , greenhouse gases , soil organic carbon , advance