Soil Temperature and Evaporation Dynamics under Water Stress in Varying Soil Textures and Amendments

Denitrification may represent an important mechanism in the fate of N applied to turf. Denitrification losses were directly measured from fertilized ‘Baron’ Kentucky bluegrass (Poa pratensis L.) sod samples sealed in acrylic chambers using the acetylene inhibition technique. Losses were correlated with soil texture, percent soil saturation (SAT), and temperature. Losses from turf on a Hadley silt loam soil and Hadley silt soil (both coarse‐silty, mixed, nonacid, mesic Typic Udifluvents) incubated at 22°C did not exceed 0.4 and 0.1%, respectively, of the applied potassium nitrate fertilizer (4.5 g N m−2) when soil water levels were less than 75% saturated. Soil saturation increased denitriflcation losses from the silt loam and silt soils to 1.1 and 5.4% of the applied N, respectively. The relationship between percent soil saturation and denitriflcation loss was quadratic and highly significant for both soils. The equations are: milligrams of N2O–N m−2 10 d−1 = 1432.50 − 38.96 (percent SAT silt soil) + 0.26 (percent silt soil)2 or 130.80 − 5.40 (percent SAT silt loam soil) + 0.05 (SAT silt loam soil)2. A linear relationship [milligrams of N2O m−2 10 d−1 = 0.49(°C) − 9.70] existed between denitrification losses and soil temperatures between 11 and 30°C in the silt soil at 75% of soil saturation. Soil temperatures of 30°C or greater coupled with saturated soil conditions resulted in the greatest losses, equivalent to 44.6 and 92.6% of the applied N to the silt loam and silt soils, respectively. Denitrification losses did not increase at soil temperatures above 30°C. These results indicate that denitrification loss from fertilizers applied to turfgrasses may not be a serious problem unless the soils are saturated and at higher soil temperatures.

Afforestation, as one of the major drivers of land cover change, has the potential to provide a wide range of ecosystem services (ES). Aside from carbon sequestration, it can improve hydrological regulation by increasing soil water storage capacity and reducing surface water runoff.  However, afforested areas are rarely studied at the appropriate time scale to determine when changes in soil hydrological processes occur as the forest grows. This study investigates the seasonal soil moisture and temperature dynamics, as well as the event-based responses to precipitation events and dry periods between a mature and juvenile forest ecosystem over a 5-year time period. Generally, soil moisture was higher in the juvenile forest than in the mature forest, indicating less physiological water demand. However, following the 2018 drought, soil moisture dynamics in the growing juvenile plantation began to match those of the mature forest, owing to canopy development and possibly also to internal resilience mechanisms of the young forest to external perturbations. On the other hand, soil temperature dynamics in the juvenile plantation followed air temperature patterns closely, indicating lower thermal regulation capacity compared to the mature forest. While our findings reveal that an aggrading juvenile plantation achieves mature forest soil moisture dynamics at an early stage, well before maturity, this was not the case for soil temperature. Our results shed light on long-term trends of seasonal and event-based responses of soil moisture and temperatures in different-aged forest systems, which can be used to inform future assessments of hydrological and ecosystem responses to disturbances and forest management.

Afforestation, as one of the major drivers of land cover change, has the potential to provide a wide range of ecosystem services. Aside from carbon sequestration, afforestation can improve hydrological regulation by increasing soil water storage capacity and reducing surface water runoff. However, afforested areas are rarely studied over time scales appropriate to determine when changes in soil hydrological processes occur as the planted (mixed) forests establish and grow. This study investigates the seasonal soil moisture and temperature dynamics, as well as the event‐based responses to precipitation and dry periods, for a mature and a juvenile forest ecosystem over a 5‐year time period. Generally, soil moisture was higher in the juvenile forest than in the mature forest, suggesting a lower physiological water demand. Following the 2018 drought, soil moisture dynamics in the growing juvenile plantation began to match those of the mature forest, owing to canopy development and possibly also to internal resilience mechanisms of the young forest to these external hot weather perturbations. Soil temperature dynamics in the juvenile plantation followed air temperature patterns closely, indicating lower thermal regulation capacity compared to the mature forest. While our findings show that an aggrading juvenile plantation achieves mature forest shallow soil moisture storage dynamics at an early stage, well before physiological maturity, this was not the case for soil temperature. Our results shed light on long‐term trends of seasonal and event‐based responses of soil moisture and temperatures in different‐aged forest systems, which can be used to inform future assessments of hydrological and ecosystem responses to disturbances and forest management.

Field-scale assessment of direct and indirect effects of soil texture on organic matter mineralization during a dry summer

To investigate the effects of management practices on the dynamics of soil temperature, during 2014–2017, a field experiment was carried out in Bad Lauchstaedt, Germany. In this study, four management systems are compared for determining management-induced changes in soil temperature at different depths: (i) conventional tillage (TC) with the standard rate of N fertilizer (P1N1), (ii) conventional tillage with the half-standard rate of N fertilizer (P1N0), (iii) reduced tillage (TR) with the standard rate of N fertilizer (P0N1), and iv) reduced tillage with the half-standard rate of N fertilizer (P0N0). Temporal analysis of soil temperature is assessed to examine data observed at a specific time to achieve a better understanding of the soil temperature dynamic that occurs at different time scales. The results showed that the soil temperature has decreasing amplitudes and increasing phase shifts with increasing soil depth, i.e., the deeper the measurement depth, the smoother the soil temperature changes cycle and the smaller the variability. Results showed that the diurnal temperature variation is found up to 45 cm depth of soil whereas annual temperature variation is up to a depth of 180 cm. The results, moreover, revealed that soil temperature dynamic was affected by tillage systems and fertilization and a time lag is observed between the temperature fluctuations at the surface and deeper layers, due to induced management effects on plant cover, residues, and soil properties. Although higher soil temperature at the sowing stage under TR is contributed to higher amounts of surface crop residues in crop rotations, the effect of residues on soil temperature variation reduces with an increase in percent plant cover and shading of soil, which happens in the last stage of plant growth. At the last stage of crop development regardless of tillage systems, applying more N fertilization increased crop yield, resulting in cooling soil temperature.

Spring crop growth is often influenced by water stress and lower soil temperature in the northern Canadian prairies. Tillage system effects on soil temperature, moisture and establishment of barley and canola in silt loam and sandy loam soils in northern British Columbia were investigated in 1992 and 1993. The tillage systems were: no-tillage (NT), modified no-tillage where surface residue was pushed aside from a 7.5cm zone above the planting rows (MNT), and conventional tillage (CT). The MNT and CT had higher weekly maximum and weekly mean seed zone temperatures than NT. Mean weekly maximum seed-zone soil temperature was 1.6°C lower in MNT and 3.7°C lower in NT than in CT during the first 10 weeks after planting (WAP) in 1992. Compared to NT and MNT, barley in CT was slow to establish during the first three WAP in the silt loam in 1992 and 1993, and in the sandy loam in 1992, due to early water stress from low rainfall. Barley emergence was delayed by 6 days in NT and 11 days in CT in 1992 and by 3 days in NT and 7 days in CT in 1993 compared to MNT in the silt loam soil. Early in the growing season, barley growth was retarded more in the CT than NT and MNT at both sites. Canola growth was significantly improved in the MNT over that in the NT and CT in 1993. The MNT was more beneficial for crop establishment during prolonged dry periods than CT, and for emergence and growth compared with NT under extremely wet soil conditions.

The variability of soil thermal and hydrological dynamics with vegetation cover in a permafrost region

In sub-Arctic environment as in Finland, soil moisture and temperature dynamics affect the development of soil frost that controls snowmelt runoff, infiltration and recharge in winter periods. This study was initiated to investigate the performance of integrated hydrology model Amanzi-ATS, in simulating dynamics of soil moisture and temperature at different depths to assess recharge rate in unconfined aquifer in Central Finland. Our objective is to study intra- and inter-annual recharge rates, and the impacts of soil ice on groundwater recharge rate. Hourly soil water content and temperature was measured at ten different depths. The groundwater depth and temperature were measure daily from the borehole located 2 meters from the soil monitoring station and the climate data was obtained around 5 km from the soil station. 1D model with varying soil texture was developed to predict recharge rates. Measured soil water content, soil temperature and groundwater temperature were used to calibrate the 1D numerical model. The implications of this study will be understanding the freezing and thawing of soil on groundwater recharge rate and how recharge rate may change from one year to the next in the sub-Arctic environment.

The turfgrass area in Lewistown, PA, consisted primarily of fine fescue (80%) and weeds (20%). Treatment plots were 8 X 6 ft, arranged in a RCB block design and replicated 3 times. Granular formulations were applied with a hand-held shaker, and top dressing sand was added to facilitate product distribution. Liquid formulations were applied with a CO2 compressed air sprayer with 4 8002VS TeeJet nozzle mounted on a 6-ft boom, operating at 28 psi, and applied in 726 ml of water/48 ft2 or delivering 4 gal/1000 ft2. At the 1st treatment time (19 May) the following soil and environmental conditions existed: air temperature, 72° F; soil temperature at 1 inch depth, 71° F; soil temperature at 2 inch, 68° F; RH, 70%; amount of thatch, 0.0625 inch; soil textural class, silt loam; soil particle size analysis: % sand, 28.8; % silt, 56.4; % clay, 14.8; organic matter, 3.7%; percent water content (percent of weight), 19.9; water pH, 7.0; soil pH, 6.0; application time, late morning; and skies cloudy. Immediately after application each treatment was irrigated with 0.25 inch of water. At the 2nd treatment time (11 Jun) the following soil and environmental conditions existed: air temperature, 75° F; soil temperature at 1-inch depth, 74° F; soil temperature at 2 inch, 69° F; RH, 80.0%; amount of thatch, 0.0625 inch; soil textural class, silt loam; soil particle size analysis: % sand, 22.4; % silt, 62.6; % clay, 15.0; organic matter, 4.3%; percent water content (percent by weight), 20.7; water pH, 7.0; soil pH, 5.9; application time, mid-morning; and skies sunny. Immediately after application each treatment was irrigated with 0.25 inch of water. At the 3rd treatment time (14 Jul) the following soil and environmental conditions existed: air temperature, 98° F; soil temperature at 1-inch depth, 91° F; soil temperature at 2 inch, 87° F; RH, 76%; amount of thatch, 0.0625 inch; soil textural class, silt loam; soil particle size analysis: % sand, 28.9; % silt, 56.2; % clay, 14.9; organic matter, 6.2%; percent water content (percent by weight), 13.5; water pH, 7.0; soil pH, 5.7; application time, mid-morning; and skies sunny. Immediately after application each treatment was irrigated with 0.25 inch of water. At the 4th treatment time (21 Aug) the following soil and environmental conditions existed: air temperature, 71° F; soil temperature at 1-inch depth, 70° F; soil temperature at 2 inch. 68° F; RH, 74%; amount of thatch, 0.0625 inch; soil textural class, silt loam; soil particle size analysis: % sand, 26.3% silt, 60.4; % clay, 13.3; organic matter, 4.2%; percent water content (percent by weight), 20.8; water pH, 7.0; soil pH, 6.1; application time, mid-morning; and skies sunny. Immediately after application, each treatment was irrigated with 0.25 inch of water. Post-treatment counts were made on 18 Sep. Three ft2 sod samples were randomly taken from each replicate, and the total number of scarab white grubs/ft2 was recorded.

The aim was to evaluate the influence of soil covers on the dynamics of soil temperature and moisture, canopy air temperature, and yield of creeping fresh market tomatoes. The experiment was carried out in randomized blocks design, using the tomato cultivar Thaise, with 5 treatments, 4 replications, with different soil covers: a) Uncovered soil (conventional planting); b) Mulching (double-sided plastic film - black and white); c) Sorghum; d) Sudan grass and e) Pearl millet), cultivated in Tangará da Serra, Mato Grosso, Brazil. Soil temperature was monitored at depths of 5, 10, 20, and 30 cm and in the crop canopy, using thermocouple sensors of the type "K". Soil moisture was monitored in the 0 to 30 cm layer, using of time-domain reflectometry (TDR) probes. Soil temperature and moisture were evaluated throughout the cycle and, in the end, the total and commercial yield of tomato crop. Soil covers have a positive influence on soil temperature and moisture in the cultivation of creeping fresh market tomatoes so that soil cover with mulching provides the highest soil temperature in the early stages of development and covers with mulching and pearl millet provide the highest values of soil moisture. The highest total and commercial yield of tomato were in the soil cover with mulching, with 110.71 and 75.93 t ha-1, respectively, presenting ideal ranges of temperature and soil moisture, so that the other treatments do not differ from each other, with the average total yield of 91.45 t ha-1.

High air or soil temperature is a major factor limiting growth of cool‐season grasses during summer months in the transition zone and warm climate regions. Knowledge of how cool‐season grasses respond to differential high air and soil temperatures would facilitate our understanding of heat tolerance mechanisms. The objectives of this study were to compare the influence of air versus soil temperature on turf quality, physiological activities, and root growth of creeping bentgrass (Agrostis palustris Huds. cv. Penncross), and to investigate whether shoot and root growth could be improved by reducing soil temperature at high air temperatures. Shoots and roots were exposed to four air/soil temperature regimes (20/20, 20/35, 35/20, and 35/35°C) for 56 d in growth chambers. High soil (20/35°C) and high air/soil (35/35°C) temperatures reduced canopy photosynthetic rate (Pn), turf quality, and the number of roots. High air/soil temperatures also reduced photochemical efficiency (Fv/Fm). The adverse effects of high air/soil temperatures were more pronounced than either high soil or air temperature alone for turf quality, Fv/Fm, Pn, and root growth. High soil temperature was more detrimental than high air temperature. Lowering soil temperature at high air temperatures (35/20°C) increased root growth, canopy Pn, Fv/Fm, and turf quality, compared with high soil temperature at low or high air temperatures (20/35 and 35/35°C). The results demonstrated that roots mediated shoot responses to high temperature stress in creeping bentgrass, and that reducing root‐zone temperature could help maintain quality creeping bentgrass under supraoptimal ambient temperatures.

Soil temperature plays an important role in understanding hydrological, ecological, meteorological, and land surface processes. However, studies related to soil temperature variability are very scarce in various parts of the world, especially in the Indian Himalayan Region (IHR). Thus, this study aims to analyze the spatio-temporal variability of soil temperature in two nested hillslopes of the lesser Himalaya and to check the efficiency of different machine learning algorithms to estimate soil temperature in the data-scarce region. To accomplish this goal, grassed (GA) and agro-forested (AgF) hillslopes were instrumented with Odyssey water level and decagon soil moisture and temperature sensors. The average soil temperature of the south aspect hillslope (i.e., GA hillslope) was higher than the north aspect hillslope (i.e., AgF hillslope). After analyzing 40 rainfall events from both hillslopes, it was observed that a rainfall duration of greater than 7.5 h or an event with an average rainfall intensity greater than 7.5 mm/h results in more than 2 °C soil temperature drop. Further, a drop in soil temperature less than 1 °C was also observed during very high-intensity rainfall which has a very short event duration. During the rainy season, the soil temperature drop of the GA hillslope is higher than the AgF hillslope as the former one infiltrates more water. This observation indicates the significant correlation between soil moisture rise and soil temperature drop. The potential of four machine learning algorithms was also explored in predicting soil temperature under data-scarce conditions. Among the four machine learning algorithms, an extreme gradient boosting system (XGBoost) performed better for both the hillslopes followed by random forests (RF), multilayer perceptron (MLP), and support vector machine (SVMs). The addition of rainfall to meteorological and meteorological + soil moisture datasets did not improve the models considerably. However, the addition of soil moisture to meteorological parameters improved the model significantly.

Extreme soil temperatures disrupt plant and soil organism functions, causing slow growth, reduced water and nutrient uptake, increased susceptibility to pests and diseases, and potential death of beneficial microbes and nematodes. A thorough understanding of the dynamics of soil temperature is vital for successful farming practices. This study was conducted at the Botswana University of Agriculture and Natural Resources research farm to evaluate the soil temperature dynamics both spatially and temporally under SLECI and conventional surface drip irrigation. Two plots were used; drip irrigation was installed on one and SLECI on the other. At the first plot, the SLECI element was located 20 cm below the soil surface, with three Time Domain Reflectometry (TDR) probes placed 10 cm above and below the SLECI element for continuous spatial and temporal observation of soil temperature. On the second plot, a total of six (6) TDR probes were placed below the surface dripper; three were placed 5 cm below the dripper, and another three were placed 15 cm below the dripper. The results show that day and night soil temperatures were 14.9 °C- 25.4 °C for SLECI observations that were 5 cm above the SLECI element, whereas for those 10 cm below the SLECI element the temperatures ranged from 16.9 °C- 25.9 °C. whereas for the drip, day and night soil temperatures were 10.4 °C- 25.5 °C for observations that were 5 cm below the dripper, whereas for those 15 cm below the drip ranged from 14.4 °C- 23.2 °C. As for the drip, soil temperature temporal and spatial distribution under SLECI irrigation were significantly different from those under surface drip at α = 0.050. The magnitude of soil temperature variations at night and during the day reduced with depth under both irrigation systems, thus protecting the plant rooting system against abrupt soil temperature changes. Further studies to investigate the influence of soil moisture distribution by the irrigation systems for another season on the soil temperature dynamics is necessary.

The dynamics of soil moisture and its temperature is an important criterion for evaluating soil tillage technology in terms of achieving plant production stability. Understanding changes in soil moisture and temperature depending on rainfall and air temperature is necessary to develop application models for agriculture 4.0. A hypothesis was adopted assuming that the dynamics of soil moisture and its thermal properties will depend on the technology of cultivation. Hence, the aim of the research was to learn the dynamics of soil moisture and temperature during a growing season using strip and conventional tillage. Soil moisture was monitored using TDR probes in the row and inter-row of winter barley using plowing and strip-till techniques. Soil temperature was also monitored. Measurements were made every 5 min. In the most important period for the growth and development of barley vegetation, the soil in the strip-till was characterized by greater moisture (3.6% v/v on average) and greater stability than was the case with plowing. The soil in the strip-till was cooler (an average of 0.64 °C), but more stable than in plowing—temporary temperature differences in ST vs. PT reached even more than 5 °C. Strip-till therefore mitigates weather extremes to a greater extent than plowing.

Investigating soil temperature and the heat transfer process is essential for understanding water–heat changes and energy balance in farmland. The conversion from upland fields (UFs) to paddy fields (PFs) alters the land cover, irrigation regimes, and soil properties, leading to differences in soil temperature, thermal properties, and heat fluxes. Our study aimed to quantify the effects of converting UFs to PFs on soil temperature and heat transfer processes, and to elucidate its underlying mechanisms. A long-term cultivated UF and a newly developed PF (converted from a UF in May 2015) were selected for this study. Soil water content (SWC) and temperature were monitored hourly over two years (June 2017 to June 2019) in five soil horizons (i.e., 10, 20, 40, 60, and 90 cm) at both fields. The mean soil temperature differences between the UF and PF at each depth on the annual scale varied from −0.1 to 0.4 °C, while they fluctuated more significantly on the seasonal (−0.9~1.8 °C), monthly (−1.5~2.5 °C), daily (−5.6~4.9 °C), and hourly (−7.3~11.3 °C) scales. The SWC in the PF was significantly higher than that in the UF, primarily due to differences in tillage practices, which resulted in a narrower range of soil temperature variation in the PF. Additionally, the SWC and soil physicochemical properties significantly altered the soil’s thermal properties. Compared with the UF, the volumetric heat capacity (Cs) at the depths of 10, 20, 40, 60, and 90 cm in the PF changed by 8.6%, 19.0%, 5.5%, −4.3%, and −2.9%, respectively. Meanwhile, the thermal conductivity (λθ) increased by 1.5%, 18.3%, 19.0%, 9.0%, and 25.6%, respectively. Moreover, after conversion from the UF to the PF, the heat transfer direction changed from downward to upward in the 10–20 cm soil layer, resulting in a 42.9% reduction in the annual average soil heat flux (G). Furthermore, the differences in G between the UF and PF were most significant in the summer (101.9%) and most minor in the winter (12.2%), respectively. The conversion of the UF to the PF increased the Cs and λθ, ultimately reducing the range of soil temperature variation and changing the direction of heat transfer, which led to more heat release from the soil. This study reveals the effects of farmland use type conversion on regional land surface energy balance, providing theoretical underpinnings for optimizing agricultural ecosystem management.