Soil Thermal Properties under Prairies, Conservation Buffers, and Corn–Soybean Land Use Systems

Abstract

Although prairies and conservation buffers are becoming popular to improve soil properties and environmental quality, very little is known about their influence on soil thermal properties. This study compared and quantified thermal conductivity (λ), thermal diffusivity (D), and volumetric heat capacity (C) of prairies (Tucker Prairie [TP] and Prairie Fork [PF]), conservation buffers (grass buffers [GB] and agroforestry buffers [AGF]), and corn (Zea mays L.)–soybean [Glycine max (L.) Merr.] rotation (COS) land uses in Missouri. Core and bulk soils were collected at 10‐cm depth increments. Soil thermal properties and water characteristic curves were determined at 0, −33, −100, and −300 kPa pressures. Additionally, soil organic C (SOC) and bulk density (BD) were also determined. The results showed that SOC was negatively correlated with λ and D and positively correlated with C. Significantly higher values of SOC and lower BD were observed for AGF, TP, GB, and PF than COS. Similarly, λ and D were significantly higher and C was lower under COS than the prairies and conservation buffers. The results suggest that a greater amount of SOC decreases the thermal conductance due to the insulating characteristics of SOC and acts as a barrier to heat transport. Therefore, AGF, TP, GB, and PF had lower thermal conductance to deeper soil depths, which helps to conserve more moisture as well as assist in increasing the longevity of SOC in the soil matrix. Our results imply that buffers and perennial vegetation can help reduce heat flow by increasing the thermal capacity and thereby mitigating climate change.

Do Cover Crops and Corn Residue Removal Affect Soil Thermal Properties?

“…Additionally, volumetric water content explained 52% of variability in thermal conductivity for the 0‐ to 5‐cm depth at the –0.033‐MPa potential (Table 7). The positive correlation of thermal conductivity with volumetric water content and bulk density is similar to the relationships reported by previous studies (Abu‐Hamdeh and Reeder, 2000; Adhikari et al, 2014; Haruna et al, 2017). Water films between soil particles and within aggregates act as heat conducting bridges (Ghuman and Lal 1985; Abu‐Hamdeh and Reeder, 2000).…”

“…Thermal diffusivity is the ratio of soil thermal conductivity to soil volumetric heat capacity and refers to how fast heat travels through the soil (Hillel, 2004). These properties influence many soil processes including soil temperature distribution, soil water storage, seed germination, microbial activities, surface energy balance, and resilience of soil to potential climatic fluctuations (Richard and Cellier, 1998; Hillel, 2004; Adhikari et al, 2014).…”

“…Thermal conductivity is often positively correlated with volumetric water content and bulk density and negatively with air‐filled porosity and soil organic C concentration (Ghuman and Lal, 1985; Potter et al, 1985; Abu‐Hamdeh and Reeder, 2000; Ochsner et al, 2001; Abu‐Hamdeh, 2003; Adhikari et al, 2014). Soil volumetric heat capacity can have a positive relationship with volumetric water content, bulk density, and soil organic C concentration (Ghuman and Lal, 1985; Potter et al, 1985; Abu‐Hamdeh, 2003; Adhikari et al, 2014; Lu et al, 2014). However, correlations of other soil thermal properties with soil properties have not been studied under the potentially interacting effects of crop residue removal and CC addition.…”

“…Specifically, information on how soil thermal conductivity, volumetric heat capacity, and thermal diffusivity change under CC, crop residue management, and their interactions in irrigated cropping systems is needed. Most studies on thermal properties have been conducted in rainfed systems (Potter et al, 1985; Adhikari et al, 2014; Haruna et al, 2017). Crop residue production and CC performance often differ between irrigated and rainfed systems (Ruis et al, 2017) and may affect soil thermal properties differently.…”

Cover Crop Effects on Corn Plant Sap Flow Rates and Soil Water Dynamics

“…5), indicating greater infiltration and soil water holding capacity of CC soils. The addition of extra OM by the CC may have improved soil moisture‐holding capacity and water infiltration of the CC soil, since available soil moisture doubles when soil C increases from 1.4 to 4% (Hudson 1994), and soil moisture storage potential increases with soil organic C due to its insulating characteristics, causing decreased thermal conductance and increased specific heat of soils (Adhikari et al, 2014). Our soil data show that OM in 2017 at the site was 3.87, 2.87, and 4.75% in CC and 3.62, 2.62, and 4.37% in NCC at the 10‐, 20‐, and 30‐cm depths, respectively.…”