| 地下滴灌对番茄根际微区氮循环微生物量及土壤N2O排放的调控机制 |
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| 引用本文： | 王京伟,李元,牛文全.地下滴灌对番茄根际微区氮循环微生物量及土壤N2O排放的调控机制[J].环境科学研究,2021,34(6):1425-1433. |
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| 作者姓名： | 王京伟 李元 牛文全 |
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| 作者单位： | 1.山西财经大学资源环境学院, 山西 太原 030006 |
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| 基金项目： | 国家自然科学基金项目51679205 |
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| 摘 要： | 为探明地下滴灌对番茄根际微区氮循环微生物及土壤N2O排放的影响，采用静态暗箱原位采集法，研究了不同滴灌管埋深（0、10、20、30 cm，依次记为CK、S10、S20、S30处理）对番茄根区土壤水分、养分、根系形态、微生物及N2O排放的影响.结果表明:S10处理可提高10~20 cm土壤含水率，其土壤NO3--N含量、DOC（溶解性有机碳）含量、根系分叉数、开花坐果期反硝化菌数量、果实成熟期亚硝化菌和反硝化菌数量分别为CK处理的2.02、1.49、1.85、3.81、2.11和3.75倍（P < 0.05），且0~20 cm土壤孔隙度较CK处理增加了10.72%（P < 0.05），N2O排放量为CK处理的1.99倍（P < 0.05）.S20处理显著提高了20~30 cm土壤含水率，其土壤NO3--N含量、DOC含量、根系分叉数、开花坐果期反硝化菌数量、果实成熟期亚硝化菌和反硝化菌数量分别为CK处理的2.66、1.38、2.77、6.0、5.56和12.50倍（P < 0.05），且0~20 cm土壤孔隙度较CK处理增加了22.32%（P < 0.05），N2O排放量为CK处理的2.24倍.S30处理形成0~20 cm土壤“干层”和20~40 cm土壤“湿层”，土壤NO3--N含量、根系分叉数、开花坐果期亚硝化细菌和反硝化细菌数量分别为CK处理的1.66、2.22、2.00和1.80倍（P < 0.05），但DOC含量、0~20 cm土壤孔隙度、反硝化细菌数量等显著低于S20处理（P < 0.05），N2O排放量与CK处理无显著差异（P < 0.05）.地下滴灌方式下土壤N2O排放主要为反硝化作用，不同滴灌管埋深形成的土壤水分分布会影响根系分叉数和0~20 cm土壤孔隙度，调节NO3--N和DOC含量、亚硝化细菌和反硝化细菌生物量，影响“根系-土壤-微生物”的交互作用和N2O排放量.S10、S20处理下根区环境利于增强“根系-土壤-微生物”的交互作用、促进反硝化作用和N2O排放，S30处理相对会减弱“根系-土壤-微生物”的交互作用、抑制N2O排放.研究显示，地下滴灌管埋深（土壤供水位置）通过调节根际微区土壤环境，改变氮循环微生物组成，进而影响“根系-土壤-微生物”的交互作用效应和土壤N2O排放量.
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| 关 键 词： | 地下滴灌 土壤N2O 根区土壤 亚硝化细菌 反硝化细菌 |
| 收稿时间： | 2020-07-28 |
Regulation Mechanism of Subsurface Drip Irrigation on Nitrogen Circulating Microorganisms and N2O Emission in Rhizosphere Microzone |
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| Affiliation: | 1.College of Resources and Environment, Shanxi University of Finance and Economics, Taiyuan 030006, China2.Institute of Soil and Water Conservation, Northwest A&F University, Yangling 712100, China3.Institute of Soil and Water Conservation, CAS & MWR, Yangling 712100, China4.Shaanxi Normal University, Xi'an 710119, China |
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| Abstract: | In order to determine the regulation mechanism of subsurface drip irrigation on soil nitrous oxide (N2O) emissions and improve soil and water management measures, this work explored the effect of different depth of drip irrigation pipes (0, 10, 20 and 30 cm, i.e. CK, S10, S20 and S30) on soil microenvironment factors (moisture, nutrient and root morphology) and N2O emission using the static opaque chamber method. In addition to the emission of soil N2O, soil NH4+-N and NO3--N, dissolved organic carbon (DOC), 0-20 cm soil porosity (SP), root forks number (RF), denitrifying bacteria (DB) and nitrite bacteria (NB) were measured. The effects of these factors on N2O emission were quantitatively analyzed by the structural equation model. The results showed that S10 increased the moisture content of 10-20 cm soil. The contents of soil NO3--N, DOC, RF, DB of flowering and fruit bearing period (FFBP), and NB and DB of fruits maturing period (FMP) in S10 were 2.02, 1.49, 1.85, 3.81, 2.11 and 3.75 times higher than that of CK (P < 0.05), respectively. The SP in S10 was 10.72% greater than that of CK (P < 0.05), and the total cumulative emissions of soil N2O (T-N2O) in S10 was 1.99 times higher than that of CK (P < 0.05). S20 increased the moisture content of 20-30 cm soil. The contents of soil NO3--N, DOC, RF, DB of FFBP, NB and DB of FMP in S20 were 2.66, 1.38, 2.77, 6.0, 5.56 and 12.5 times higher than that of CK (P < 0.05), respectively. The SP in S20 was 22.32% higher than that in CK (P < 0.05), and the T-N2O in S20 was 2.24 times that of CK (P < 0.05). S30 formed the 'dry layer' of 0-20 cm soil and the 'wet layer' of 20-40 cm soil. The contents of soil NO3--N, RF, NB and DB of FMP in S30 were 1.66, 2.22, 2.00 and 1.80 times that of CK (P < 0.05), respectively. The DOC, SP and DB of FFBP and FMP in S30 were significantly lower than those of S20 (P < 0.05), and there was no significant difference between T-N2O in S30 and CK (P < 0.05). The soil N2O emission from subsurface drip irrigation was mainly caused by the denitrification process. Soil moisture distribution formed by different depths of drip irrigation pipes affected RF and SP, as well as soil NO3--N, DOC, NB and DB, and ultimately effected the interaction of 'root-soil-microorganism' and N2O emission. The root zone environment created by S10 and S20 was conducive to enhancing the 'root-soil-microorganism' interaction and promoting the denitrification and N2O emission, while S30 relatively weakened the 'root-soil-microorganism' interaction and inhibited N2O emission. Thus, the depth of subsurface drip irrigation pipe (the location of soil water supplied) affects the interaction of 'root-soil-microorganism' and soil N2O emission by regulating the rhizosphere soil environment and changing the composition of nitrogen circulating microorganisms. |
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