Zhang Wencan, Gao Weida, Whalley William Richard, Ren Tusheng
Department of Soil and Water Sciences China Agricultural University Beijing China.
Department of Sustainable Agricultural Sciences Rothamsted Research Harpenden UK.
Eur J Soil Sci. 2021 Mar;72(2):782-792. doi: 10.1111/ejss.13007. Epub 2020 Jun 28.
Plant roots release various organic materials that may modify soil structure and affect heat and mass transfer processes. The objective of this study was to determine the effects of a synthetic root exudate (SRE) on penetrometer resistance (PR), thermal conductivity (λ), hydraulic conductivity () and evaporation of water in a sandy soil. Soil samples, mixed with either distilled water or the SRE, were packed into columns at a designated bulk density and water content, and incubated for 7 days at 18°C. Soil PR, λ, and evaporation rate were monitored during drying processes. Compared with those incubated with water, samples incubated with SRE had visible hyphae, greater PR (0.7-5.5 MPa in the water content range of 0.11 to 0.22 m m) and λ (0.2-0.7 W m K from 0.05 to 0.22 m m), and increased in the wet region but decreased in the dry region. SRE treatment also reduced the overall soil water evaporation rate and cumulative water loss. Analysis of X-ray computed tomography (CT) scanning showed that the SRE-treated samples had a greater proportion of small pores (<60 μm). These changes were attributed mainly to SRE-stimulated microbial activities.
The effects of incubating a sandy soil with a synthetic root exudate (SRE) on soil physical properties and evaporation are examined.SRE incubation increased the fraction of small pores.SRE incubation increased soil penetrometer resistance and thermal conductivity.Soil hydraulic conductivity was increased in the wet region but was reduced in the dry region.SRE incubation reduced the overall evaporation rate and cumulative water loss.
植物根系会释放各种有机物质，这些物质可能会改变土壤结构并影响热量和质量传递过程。本研究的目的是确定合成根系分泌物（SRE）对砂质土壤中贯入阻力（PR）、热导率（λ）、水力传导率（）和水分蒸发的影响。将与蒸馏水或SRE混合的土壤样品以指定的容重和含水量装入柱中，并在18°C下培养7天。在干燥过程中监测土壤的PR、λ、和蒸发速率。与用水培养的样品相比，用SRE培养的样品有可见的菌丝，更高的PR（在含水量为0.11至0.22 mm范围内为0.7 - 5.5 MPa）和λ（在0.05至0.22 mm范围内为0.2 - 0.7 W m K），在湿润区域增加但在干燥区域减少。SRE处理还降低了土壤整体水分蒸发速率和累积失水量。X射线计算机断层扫描（CT）分析表明，经SRE处理的样品中小孔隙（<60μm）的比例更大。这些变化主要归因于SRE刺激的微生物活动。
研究了用合成根系分泌物（SRE）培养砂质土壤对土壤物理性质和蒸发的影响。
SRE培养增加了小孔隙的比例。
SRE培养增加了土壤贯入阻力和热导率。
土壤水力传导率在湿润区域增加但在干燥区域降低。
SRE培养降低了整体蒸发速率和累积失水量。
