Immediate and subsequent effects of drying and rewetting on microbial biomass in a paddy soil
Immediate and subsequent effects of drying and rewetting on microbial biomass in a paddy soil
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干燥和再润湿对水稻土微生物量的直接和后续影响
DOI：
10.1080/00380768.2018.1534217
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发表时间：
2019
影响因子：
2
通讯作者：
Takashi Kosaki
中科院分区：
文献类型：
--
作者：
Kozue Sawada;Shinya Funakawa;Takashi Kosaki
由于未来的气候变化，日本许多表层土壤可能会经历更频繁和更强烈的干燥-再湿润（DRW）事件。这些DRW事件分别通过微生物胁迫和底物供应机制对微生物生物量碳（MBC）产生负面和正面影响。为了评估DRW后立即和反复DRW循环培养期间的MBC，对水稻土进行了两个实验室实验。在第一个实验中，我们将土壤暴露于不同的干燥处理，并在复湿后立即检查MBC和每小时呼吸速率，以评估微生物胁迫。在第二个实验中，我们比较了微生物的生长速率在培养过程中的部分灭菌的土壤与连续潮湿的条件下，并重复DRW周期，以评估从非生物质土壤有机碳MBC的基板供应的贡献。首先，所有的干燥处理引起的MBC减少后立即再润湿，和更高的干燥强度诱导更高的MBC减少率。MBC中超过20%的减少诱导了存活微生物的C饱和条件，因为从死MBC中释放了足够浓度的不稳定底物C。第二，重复的DRW循环导致微生物生长速率的增加，因为基质C由非生物质有机C提供。总之，由于微生物胁迫，MBC在DRW后立即下降，而由于非生物质有机C提供的底物C，MBC在重复DRW循环期间增加。
Many surface soils in Japan may experience more frequent and intense drying–rewetting (DRW) events due to future climate changes. Such DRW events negatively and positively affect microbial biomass carbon (MBC) through microbial stress and substrate supply mechanisms, respectively. To assess the MBC immediately after DRW and during the incubation with repeated DRW cycles, two laboratory experiments were conducted for a paddy soil. In the first experiment, we exposed the soil to different drying treatments and examined the MBC and hourly respiration rates immediately after the rewetting to evaluate the microbial stress. In the second experiment, we compared microbial growth rates during the incubation of the partially sterilized soil with a continuously moist condition and repeated DRW cycles to evaluate the contribution of the substrate supply from non-biomass soil organic C on MBC. First, all drying treatments caused a reduction in MBC immediately after the rewetting, and higher drying intensities induced higher reduction rates in MBC. A reduction of more than 20% in MBC induced the C-saturated conditions for surviving microbes because sufficient concentrations of labile substrate C were released from the dead MBC. Second, repeated DRW cycles caused increases in the microbial growth rates because substrate C was supplied from non-biomass organic C. In conclusion, MBC decreased immediately after DRW due to microbial stress, whereas MBC increased during repeated DRW cycles due to substrate C supplied from non-biomass organic C.