加气灌溉下气候因子和土壤参数对土壤呼吸的影响

为揭示温室内气候因子和加气灌溉下土壤温度、氧气含量和水分对土壤呼吸的影响,对比研究了加气灌溉和地下滴灌(对照)下,各因子与土壤呼吸速率的关系。结果表明:5 cm处土壤温度与土壤呼吸呈极显著正相关关系,加气灌溉和对照处理下相关系数分别为0.615和0.564,且两处理下5 cm处土壤温度分别解释了土壤呼吸变化的46.6%和32.4%。大气相对湿度和土壤氧气含量也影响着土壤呼吸的变化。加气灌溉和对照处理下,大气相对湿度解释了土壤呼吸速率变化的35.2%和23.7%。两处理下土壤氧气含量分别解释了20%左右的土壤呼吸变化。各因子交叉混合影响了76.8%(加气灌溉)和42.5%(对照)的土壤呼吸变化。由此可知,土壤温度是影响土壤呼吸变化的控制性因子,大气相对湿度和土壤氧气含量也是影响土壤呼吸变化的重要因子。各因子对土壤呼吸速率存在交叉影响,且加气灌溉下的拟合效果明显优于对照。加气灌溉下土壤含水率略有下降,土壤呼吸速率和土壤氧气含量与对照差异显著,分别提高了33.16%和16.61%。加气灌溉明显改善了根区土壤环境,土壤呼吸的其他限制因素减少,因此加气灌溉下土壤温度、大气相对湿度、土壤含水率和土壤氧气含量对土壤呼吸的交叉影响更明显,对土壤呼吸变化的拟合效果更优。

Effects of Climatic Factors and Soil Parameters on Soil Respiration under Oxygation Conditions

Oxygation, which can impose aerated water to root zoon through Venturi tube and subsurface drip irrigation (SDI), has been showing yield improvement potentials and great application prospects. The impacts of climatic factors and soil temperature, oxygen concentration and moisture on soil respiration under oxygation and no aerated subsurface drip irrigation conditions were explored. Consequently, two treatments with three replicates were included. Plot experiments were conducted in a greenhouse during tomato growing season under these two different irrigation scenarios. The seasonal variation of soil respiration rate, soil temperature, soil oxygen concentration and soil moisture were described to investigate the relativity between soil respiration rate and these factors. Results showed that with oxygation and CK, soil temperature at the depth of 5cm (T5) had a high significant positive correlation with soil respiration rate (Rs), and the correlation coefficients were 0.615 and 0.564, respectively. Meanwhile, under the oxygation and CK conditions, T5 explained 46.6% and 32.4% variation of Rs, respectively. In addition, air humidity (RH) and soil oxygen concentration (Os) also affected the variation of Rs. RH explained 35.2% and 23.7% variation of Rs under the oxygation and CK conditions, respectively. And Os explained about 20% variation of Rs for the two treatments. The interaction of these factors affected 76.8% and 42.5% variation of Rs with oxygation and CK, respectively. Therefore, soil temperature was a controlling factor that constrained the soil respiration. Air humidity and soil oxygen concentration also were the important factors affecting the variation of soil respiration. Meanwhile, these factors had an interactive effect on variation of soil respiration rate, and the fitting result under oxygation was more effective. In addition, soil moisture was declined slightly with oxygation. The soil respiration rate and soil oxygen concentration under the oxygation conditions had a significant difference with CK, which were increased by 33.16% and 16.61% compared with CK, respectively. Thus, oxygation could improve soil environment effectively, and then decrease the limiting factors of soil respiration. As a result, under oxygation conditions, soil respiration was more sensitive to the interactions of soil temperature, relative humidity, soil moisture and soil oxygen concentration, and the fitness between these factors and soil respiration was better.