加气渗灌下土壤呼吸速率变化与水-氧-热耦合效应

Changes in Soil Respiration Rates under Aerated Infiltration Irrigation and Water-Oxygen-Heat Coupling Effects

摘要:

为探明加气渗灌技术下土壤含水率、土壤含氧量与土壤温度对土壤呼吸速率（Soil respiration rate,SRR）的主导作用及协同机制,揭示加气渗灌（Aerated infiltration irrigation,AI）如何通过改善根区供氧条件,缓解高湿抑制效应,本文以国家土壤质量湛江观测实验站为平台,开展2023-2025年田间定位试验,测定加气渗灌（AI）和普通渗灌（CK）条件下SRR、土壤含水率、土壤含氧量、土壤温度季节性与昼夜变化规律,并探究其互动响应关系。结果表明：AI处理年均SRR分别提升21.0%（P＜0.05）、23.5%（P＜0.01）、22.7%（P＜0.05）,在降雨偏多年份（2025年）,CK波动更大而AI仍保持较高水平,不同处理下土壤温度差异不显著（P＞0.05）但趋势一致,土壤含水率高值出现频率降低且土壤含氧量持续提高;在典型晴好日24 h连续观测中,不同处理下土壤温度日变化与大气温度高度一致,且差异不显著（P＞0.05）,SRR均呈单峰型日变化,AI处理下日均SRR和土壤含氧量较CK分别提升22.22%和20.76%。三因子可解释SRR变化78%以上,土壤含水率与SRR呈显著正相关,土壤含氧量、土壤温度与SRR呈二次多项式负相关,且在特定温度阈值（27.5~27.6℃）后,SRR开始下降。土壤含水率与土壤含氧量是驱动SRR变化的主要因子。SEM结果显示,AI处理使氧气成为SRR的主导因子,增强“水分→氧气→SRR”的正向通路,降低土壤温度对SRR的主导效应。研究结果可为完善加气渗灌下土壤呼吸速率变化响应机理、合理制定有效的土壤碳排放调控管理措施提供理论依据。

Abstract:

Aiming to investigate the dominant roles and synergistic mechanisms of soil moisture content,soil oxygen content,and soil temperature in determining soil respiration rate (SRR) under aerated infiltration irrigation (AI) conditions,and elucidate how AI alleviates the high-humidity suppression effect by improving root zone oxygen supply,the National Soil Quality Zhanjiang Observation Station was utilized as a platform to conduct field-based,fixed-location experiments from 2023 to 2025. Seasonal and diurnal variations in SRR,soil moisture content,soil oxygen content,and soil temperature were measured under AI and conventional infiltration irrigation (CK) conditions,with their interactive responses investigated. Results indicated that AI treatments increased annual average SRR by 21.0% (P<0.05),23.5% (P<0.01),and 22.7% (P<0.05),respectively. During the rainy year (2025),CK exhibited greater fluctuations while AI maintained higher levels. Soil temperature differences were not significant (P>0.05) but showed consistent trends across treatments. The frequency of high soil moisture content was decreased,while soil oxygen content was continuously increased. During 24-hour continuous observations on typical clear days,the diurnal variations in soil temperature under different treatments highly correlated with atmospheric temperature,with no significant differences (P>0.05). SRR exhibited a unimodal diurnal variation pattern. Under AI treatment,the average daily SRR and soil oxygen content were increased by 22.22% and 20.76%,respectively,compared with that of CK. The three factors explained over 78% of SRR variation. Soil moisture content showed a significant positive correlation with SRR,while soil oxygen content and soil temperature exhibited quadratic polynomial negative correlations with SRR. Beyond a specific temperature threshold (27.5~27.6℃),SRR began to decline. Soil moisture content and soil oxygen content were the primary drivers of SRR variation. SEM results indicated that AI treatment made oxygen the dominant factor influencing SRR,strengthening the positive pathway "moisture → oxygen → SRR" and reducing the dominant effect of soil temperature on SRR. These findings can provide theoretical support for refining the response mechanism of soil respiration rate variation under aerated infiltration irrigation and for rationally formulating effective soil carbon emission control management measures.