半干旱区不同施肥量对旱作冬小麦田土壤呼吸的影响

为了探究不同施肥量对半干旱区旱作冬小麦田土壤呼吸的影响，在宁夏回族自治区彭阳县旱地农业试验站设置了不施肥（F_N）、低肥（F_L）、中肥（F_M）和高肥（F_H）大田试验。通过监测不同施肥量下冬小麦田的土壤温度、土壤水分和土壤呼吸速率，分析不同施肥量下冬小麦田土壤呼吸速率的变化特征及其与土壤水热因子的相关性。结果表明：（1）施肥能提升0~5 cm和5~10 cm土层土壤温度，随着施肥量的增加，0~5 cm和5~10 cm土层温度平均增幅分别为1.7%~15.0%和2.0%~21.4%。（2）施肥降低了0~100 cm土层土壤含水量，随着施肥量的增加，F_H、F_M和F_L处理降幅分别为6.5%~7.0%、5.0%~5.8%和3.5%~4.0%。（3）施肥显著提升了冬小麦在拔节期、抽穗期、开花期、灌浆期和成熟期的土壤呼吸速率；2018—2019年和2019—2020年低肥、中肥和高肥处理平均土壤呼吸速率分别提升了40.0%、25.5%和14.5%。（4）施肥提升了冬小麦全生育期CO₂排放量，随着施肥量的增加，全生育期CO₂排放量呈下降趋势，表现为低肥＞中肥＞高肥＞无肥，且各生育阶段土壤CO₂累计排放量存在显著差异。（5）土壤呼吸速率与土壤水热因子相关性分析表明，土壤呼吸与0~5 cm和5~10 cm土层土壤温度相关系数均达到显著水平，且与5~10 cm土层土壤温度相关性显著高于0~5 cm土层；土壤呼吸速率与0~10 cm土层土壤含水率呈现显著相关关系。（6）土壤水热双因素与土壤呼吸分析表明，土壤水热双因素可以解释土壤呼吸变化的81%~89%，高于土壤温度（63%~74%）和土壤水分（46%~75%）单因素。综上可知，土壤呼吸受土壤温度和水分的调控。从改善农田生态，降低土壤呼吸的角度来看，适当提升施肥量可有效减少土壤呼吸的排放。

Effects of different fertilizer application rates on soil respiration of dryland winter wheat fields in semi\|arid area

In order to investigate the effects of different fertilizer application rates on soil respiration in dryland winter wheat fields in semi\|arid area, field experiments with no fertilizer (F_N), low fertilizer (F_L), medium fertilizer (F_M) and high fertilizer (F_H) were conducted in Pengyang County, Ningxia Hui Autonomous Region. By monitoring the soil temperature, soil moisture and soil respiration rate of winter wheat field under different fertilizer rates, the characteristics of soil respiration rate change and the correlation with soil hydrothermal factors under different fertilizer rates were analyzed. The results showed that:(1) Fertilization increased the soil temperature of 0~5 cm and 5~10 cm soil depth, and the average soil temperature increase of 0~5 cm and 5~10 cm soil depth was 1.7%~15.0% and 2.0%~21.4%, respectively. (2) Fertilization reduced the soil water content of 0~100 cm soil depth, and with the increase of fertilization rates, F_H, F_M, and F_L decreased by 6.5%~7.0%, 5.0%~5.8%, and 3.5%~4.0%, respectively. (3) Fertilization significantly increased the soil respiration rate of winter wheat in the jointing stage, heading stage, flowering stage, filling stage and maturity stage. In 2018-2019 and 2019-2020, the average soil respiration rates of F_L, F_M, and F_H were increased by 40.0%, 25.5%, and 14.5%, respectively. (4) Fertilization increased CO₂ emissions during the whole growth period. With the increase of fertilization rates, CO₂ emissions during the whole growth period showed a downward trend, which was represented by F_L>F_M> F_H>F_N, and the cumulative emission of CO₂ in the soil at each growth stage had significant differences. (5) The correlation analysis between soil respiration rate and soil hydrothermal factors showed that the correlation coefficients between soil respiration and soil temperature of 0~5 cm and 5~10 cm soil depth reached a significant level, and the correlation between soil respiration and soil temperature of 5~10 cm soil depth was significantly higher than that of 0~5 cm soil depth. In addition, there was a significant correlation between soil respiration rate and soil moisture content of 0~10 cm soil depth. (6) Soil moisture and heat factors and soil respiration analysis showed that soil moisture and heat factors explained 81%~89% of soil respiration, which was higher than soil temperature (63%~74%) and soil moisture (46%~75%).The results indicated that soil respiration was regulated by soil temperature and water content. From the perspective of improving farmland ecology and reducing soil respiration, appropriate increase of fertilizer application can effectively reduce soil respiration emissions.