- Award ID(s):
- 2037504
- NSF-PAR ID:
- 10334709
- Date Published:
- Journal Name:
- Computers and Electronics in Agriculture
- Volume:
- 188
- Issue:
- C
- ISSN:
- 0168-1699
- Page Range / eLocation ID:
- 106331
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Long‐term soil warming can decrease soil organic matter (SOM), resulting in self‐reinforcing feedback to the global climate system. We investigated additional consequences of SOM reduction for soil water holding capacity (WHC) and soil thermal and hydrological buffering. At a long‐term soil warming experiment in a temperate forest in the northeastern United States, we suspended the warming treatment for 104 days during the summer of 2017. The formerly heated plot remained warmer (+0.39 °C) and drier (−0.024 cm3H2O cm−3soil) than the control plot throughout the suspension. We measured decreased SOM content (−0.184 g SOM g−1for O horizon soil, −0.010 g SOM g−1for A horizon soil) and WHC (−0.82 g H2O g−1for O horizon soil, −0.18 g H2O g−1for A horizon soil) in the formerly heated plot relative to the control plot. Reduced SOM content accounted for 62% of the WHC reduction in the O horizon and 22% in the A horizon. We investigated differences in SOM composition as a possible explanation for the remaining reductions with Fourier transform infrared (FTIR) spectra. We found FTIR spectra that correlated more strongly with WHC than SOM, but those particular spectra did not differ between the heated and control plots, suggesting that SOM composition affects WHC but does not explain treatment differences in this study. We conclude that SOM reductions due to soil warming can reduce WHC and hydrological and thermal buffering, further warming soil and decreasing SOM. This feedback may operate in parallel, and perhaps synergistically, with carbon cycle feedbacks to climate change.
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Abstract Soil thermal properties play important roles in dynamic heat and mass transfer processes, and they vary with soil water content (
θ ) and bulk density (ρ b ). Bothθ andρ b change with time, particularly in recently tilled soil. However, few studies have addressed the full extent of soil thermal property changes withθ andρ b . The objective of this study is to examine how changes inρ b with time after tillage impact soil thermal properties (volumetric heat capacity,C v , thermal diffusivity,k , and thermal conductivity,λ ). The study provides thermal property values as functions ofθ andρ b and of air content (n air ) on undisturbed soil cores obtained at selected times following tillage. Heat pulse probe measurements of thermal properties were obtained on each soil core at saturated, partially saturated (θ at pressure head of −50 kPa) and oven‐dry conditions. Generally,k andλ increased with increasingρ b at the three water conditions. TheC v increased asρ b increased in the oven‐dry and unsaturated conditions and decreased asρ b increased in the saturated condition. For a givenθ , a largerρ b was associated with larger thermal property values, especially forλ . The figures ofC v ,k andλ versusθ andρ b , as well asC v ,k andλ versusn air , represented the range of soil conditions following tillage. Trends in the relationships of thermal property values withθ andρ b were described by 3‐D surfaces, whereas each thermal property had a linear relationship withn air . Clearly, recently tilled soil thermal property values were quite dynamic temporally due to varyingθ andρ b . The dynamic soil thermal property values should be considered in soil heat and mass transfer models either as 3‐D functions ofθ andρ b or as linear functions ofn air .Highlights Thermal property values for a range of
θ andρ b were measured on undisturbed soil cores.Freshly tilled soil thermal property values were quite dynamic temporally.
The thermal property values of a tilled soil were described as 3‐D surfaces with
θ andρ b .The thermal property values of a tilled soil varied linearly with
n air . -
The forest drought experiment prototype at Hubbard Brook was constructed in 2015, as part of the International Drought Experiment (IDE) coordinated by the DroughtNet Research Coordination Network. The throughfall exclusion experiment was designed to simulate a 1-in-100-year drought during an average precipitation year by diverting ~50% of forest throughfall from each treatment plot starting in May 2015 (Asbjornsen et al., 2018). Throughfall was intercepted by reinforced polyethylene troughs and diverted passively to the downslope side of each plot. Each throughfall exclusion plot was 15 x 15 meters in area. TFE plots were designated with the labels 7 and 8 to avoid any confusion with the nearby CCASE plots (which are labeled 1-6). Plots were not trenched to isolate them from the surrounding soil. In May 2019 throughfall removal was increased to approximately 95% (i.e. full coverage but with stemflow not fully excluded). Throughfall exclusion treatments ended in February 2020. Recovery and return to baseline conditions were monitored during 2020 (when a natural drought occurred) and 2021 (a more normal year). These data were gathered as part of the Hubbard Brook Ecosystem Study (HBES). The HBES is a collaborative effort at the Hubbard Brook Experimental Forest, which is operated and maintained by the USDA Forest Service, Northern Research Station.more » « less
- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1016/j.compag.2021.106331
