Low Soil Temperatures Research Articles

Surging compound drought–heatwaves underrated in global soils

Compound drought-heatwaves (CDHWs) accelerate the warming and drying of soils, triggering soil compound drought-heatwaves (SCDHWs) that jeopardize the health of soil ecosystems. Nevertheless, the behavior of these events worldwide and their responses to climatic warming are underexplored. Here, we show a global escalation in the frequency, duration, peak intensity, and severity of SCDHWs, as well as an increase in affected land area, from 1980 to 2023. The increasing trends, which are particularly prominent since the early 2000 s, and projected to persist throughout this century, are dominated by summertime SCDHWs and enhanced by El Niño. Intensive soil warming as well as climatologically lower soil temperatures compared to air temperatures lead to localized hotspots of escalating SCDHW severity in northern high latitudes, while prolonged duration causes such hotspots in northern South America. Transformation of natural ecosystems, particularly forests and wetlands, to cropland as well as forest degradation substantially enhance the strength of SCDHWs. Global SCDHWs consistently exhibit higher frequencies, longer durations, greater severities, and faster growth rates than CDHWs in all aspects from 1980 to 2023. They are undergoing a critical transition, with droughts replacing heatwaves as the primary constraint. We emphasize the significant intensification of SCDHWs in northern high latitudes as well as the prolonged duration of SCDHWs in the Southern Hemisphere, posing an underrated threat to achieving carbon neutrality and food security goals.

Analyzing the Trade-Offs between Soil Health Enhancement, Carbon Sequestration, and Productivity in Central India’s Black Soil through Conservation Agriculture

The impact of conservation tillage (CST) practices on soil properties, carbon sequestration and yield sustainability over short, medium, and long durations remain insufficiently understood, especially in semiarid Central India. Therefore, our objective was to investigate the effects and optimal duration of CST adoption for enhancing soil properties, carbon sequestration, and sustainable yields. We conducted a study in farmers’ fields in the Akola district of Central India, where CST had been practised for 4 to 15 years, within a soybean + pigeon pea–chickpea cropping sequence. Our findings revealed significant (p < 0.05) improvements in soil physical properties with short-term CST practices (4 to 6 years), alongside increasing availability of nitrogen and phosphorus, with longer durations of CST implementation (10 to 15 years). The lowest soil organic carbon (SOC) was observed in conventional tillage (CT_y), while all CST practices increased SOC content over CT_y, ranging from 22.2 to 38.4%. Further, experimental soil dominated passive C pools (Cfrac3 + Cfrac4). Consequently, long-term CST practices facilitated positive C sequestration rates, contrasting with negative or minimal sequestration observed in CT_y and short-term CST treatments. However, compared to CST, CT_y demonstrated higher soybean equivalent yields and comparable chickpea equivalent yields mainly due to delayed germinations induced by lower soil temperatures in CST plots. We conclude that integrating site-specific characteristics, management practices, and regional climate conditions into conservation agriculture frameworks maximizes efficacy and ensures sustainable productivity. These findings help optimize agricultural practices considering potential yield losses or minimal changes despite implementing CST.

Potential processes leading to winter reddening of young Douglas-fir Pseudotsuga menziesii Mirb. Franco. in Europe

Key messageWinter reddening of young Douglas-fir (Pseudotsuga menziesii Mirb. Franco), triggered by large thermal fluctuations in late winter, is a critical problem for European forestry. A literature review identified certain climatic conditions that are characteristic of ‘reddening’ years, including warm daily temperatures, high daily temperature amplitude, low relative humidity, moderate wind speeds, as well as the occurrence of freeze-thaw cycles with cold night temperatures.By describing the triggering environmental and stand factors, we propose three hypotheses for the physiological processes leading to winter reddening, namely (i) hydraulic failure due to winter drought stress, (ii) photo-oxidative stress in shade-acclimated trees, and (iii) early cold deacclimation during warm periods.i) Low soil temperature, by reducing root water uptake, combined with anticyclonic conditions, by increasing water losses, can induce hydraulic failure in the xylem. Hydraulic failure may be further accelerated by night frosts.ii) Winter reddening can occur when low temperature and high irradiance coincide, disrupting photostasis. Overwhelming of winter photo-protection may lead to photodamage and subsequent reddening.iii) Warm periods, by inducing cold deacclimation, make trees susceptible to frost damage.Finally, the three processes may interact under atypical anticyclonic conditions in late winter (e.g. cold or dry soils, warm days, high irradiance and/or freezing nights). Indeed, trees under water stress would develop a higher sensitivity to freezing night and photooxidative stress. We therefore proposed mitigation actions to avoid exposing trees to stressful conditions based on e.g. stand characteristics, understorey vegetation and planting.

Mulching with Municipal Solid Waste (MSW) Compost Has Beneficial Side Effects on Vineyard Soil Compared to Mulching with Synthetic Films

Municipal solid waste (MSW) compost represents a sustainable alternative to plastic film for mulching in viticulture. This study investigated the effects of MSW compost on vineyard soil properties, specifically focusing on side effects such as soil temperature and microbial decomposition activity, independently from its role in weed control. The experiment was conducted in a vineyard located in the Mediterranean region (Southern Italy), with six different mulching treatments: black polyethylene (PE) film, black and white biodegradable film, three different amounts of MSW compost (8, 15, and 22 kg plant−1), and a control without mulching. Weed growth was monitored to determine the optimal compost application amount. The 15 kg plant−1 treatment was selected for further analyses, as it did not significantly impact weed growth compared to the control. Results indicated that MSW compost mulching maintained lower soil temperatures compared to other treatments (up to 5 °C in the warmest hours) and reduced the amplitude of the thermal wave up to 50% compared to the non-mulched soil and even more compared to black film mulched soil, particularly during the warmest periods. This suggests that MSW compost can mitigate heat stress on plant roots, potentially enhancing plant resilience and preserving crop production also in stressful growing conditions. Microbial decomposition activity, assessed using the tea bag index, was higher in the MSW compost treatment during spring compared to the control, indicating temperature as a key driver for organic matter decomposition, but this effect disappeared during summer. These findings highlight the potential of MSW compost to support sustainable viticulture by reducing reliance on synthetic mulching materials and promoting environmental sustainability through the recycling of organic municipal waste.

Study on temperature field distribution and leakage point localization of buried carbon dioxide pipeline leakage

Leakage from buried CO2 pipelines is a critical issue in the context of carbon capture and storage (CCS). Therefore, we developed a small-scale experimental system for buried CO2 pipeline leakage. to investigate the effects of leak pressure, leak aperture size, and soil type on the temperature distribution near the leak point. The results of the study showed that the lowest soil temperature appeared directly above the leak. The minimum temperature at the soil axial measurement point increased with increasing leak pressure, but the peak maximum temperature difference decreased. 3 mm and 5 mm leak pore sizes, the peak maximum temperature difference occurred at 10 cm and 20 cm, respectively. At all pressures, the maximum temperature difference peaked at 20 cm. Soil surface temperature variations were mainly influenced by leak pressure. The maximum peak temperature difference at the soil surface measurement points also increased with increasing leak pressure. Smaller leakage apertures slowed down the decrease of soil surface temperature. In addition, based on the experimental results, we propose a new method to locate leaks based on the soil temperature gradient.

Effects of Agrivoltaics on the Microclimate in Horticulture

Chilean agriculture must adapt to climate change as droughts are already affecting the country and water availability is expected to further decline. In this context, Agrivoltaics (AV) systems, that install photovoltaic (PV) panels over crops and thus provide shading and an altered microclimate could enhance the resilience of agriculture in semi-arid zones. We compare data measured under an AV system with a reference measurement to quantify the effects of AV on microclimate in horticulture in the Metropolitan Region of Santiago, Chile. Data on irradiation, air temperature, air humidity, and wind speed allow us to compute potential evapotranspiration (PET). We observe a reduction of Global Horizontal Irradiation (GHI) under the AV system of 42%. Mainly, as a result of the decreased GHI, we derive a diminution in PET of 31%, quantifying the potential to lower the water demand of crops and thus irrigation. Measured soil moisture is on average 29% higher under the AV system compared to the reference condition, hence validating PET computations. Also, we find a more moderate climate with slightly stabilized air temperature and lower soil temperatures. Our results give a glimpse of the effects of installing PV panels over horticulture crops concerning the challenges of Chilean agriculture. AV systems have the potential to increase water availability by lowering irrigation demand and protecting crops from the effects of extreme irradiation, such as sunburn and heat stress. Thus, AV could foster the transformation of agriculture towards sustainable production systems. The documented effects should be verified over longer periods with different crops to understand the impact of AV within seasonal and interannual climatical variation and the diversity of Chilean agriculture.

Impacts of wildfires on boreal forest ecosystem carbon dynamics from 1986 to 2020

Wildfires significantly change boreal forest ecosystem carbon balance through both direct combustion and post-fire carbon dynamics. Affected vegetation influences soil thermal regime and carbon cycling by impacting the surface energy balance of boreal forests. This study uses a process-based biogeochemistry model to quantify carbon budget of North American boreal forests during 1986–2020 based on satellite-derived burn severity data. During the study period, burn severity generally increases. Fires remove ecosystem carbon of 2.4 Pg C and reduce net ecosystem production (NEP) from 32.6 to 0.8 Tg C yr−1, making the forest ecosystems lose 3.5 Pg C, shifting a carbon sink to a source. The canopy’s cooling effect leads to lower soil temperature and lower net primary production due to lower nitrogen mineralization and uptake. Post-fire NEP decreases from 1.6 to 0.8 Tg C yr−1. This reduction accounts for 50% of the simulated NEP when the effects of fire-affected canopy are not considered. Our study highlights the importance of wildfires and their induced-canopy changes in soil thermal and ecosystem carbon dynamics of boreal forests.

Effects of reduced snowpack due to climate warming on abiotic and biotic soil properties in alpine and boreal forest systems

Reduction in snow cover, depth, onset, and duration of seasonal snow in mid-latitude regions due to climate warming has multiple global and local scale ecosystem impacts. These effects include modulations of the hydrological cycles and increases in land surface solar radiation absorption due to decreased albedo. Changes in snow cover characteristics also affect underlying soils. Snow has an insulating effect on soils by decoupling air and soil temperatures, thus seasonal snow cover reduction leads to overall lower soil temperatures and an increase in freeze-thaw cycles. This is especially prominent during the fall and spring thaw seasons when the snow cover is not as extensive. This in turn has downstream impacts on soil physical, chemical, and biological properties. Among these impacts are soil moisture reduction, temperature, frost regimes, soil pH shifts, and alteration in nutrient flux dynamics during winter, snowmelt period and the following summer growing season. These changes in soil physicochemical properties due to snowpack reduction can then impact the biological soil properties via increased plant root mortality, reduced abundance and diversity of soil arthropods, and shifts in composition, abundance and activity of soil microbial communities. All these soil biotic factors can in turn alter the dynamics of soil nutrient fluxes and future greenhouse gas emissions. Here, we integrate data on the effects of snow cover reduction on abiotic and biotic soil properties, with focus on temperate alpine and forest ecosystems and with an outlook on future impacts.

Effects of Black and White Mulch on Mycelial Growth of Tuber Species in Korean Field Environment

Truffles, belonging to the genus Tuber, are ectomycorrhizal (ECM) fungi that form underground ascocarps and primarily establish symbiosis with oaks and hazels. The cultivation of Tuber spp. involves transplanting inoculated seedlings that have formed ectomycorrhiza with Tuber species, with mulching being effective for truffle cultivation. In this study, we investigated the effects of mulching on the mycelial growth of four Tuber species (T. himalayense, T. koreanum, T. melanosporum, and T. borchii) in the Korean natural environment, highlighting the potential for Korea as a truffle cultivation site. We developed and tested species-specific primers for quantifying the soil mycelial biomass of Tuber spp. by qRT-PCR, determined the superior mulch color for mycelial growth, and identified the Tuber species exhibiting the highest growth rate in the Korean field environment. Our results demonstrated that white mulch significantly enhanced mycelial growth in Tuber species than black mulch, likely owing to its ability to maintain low soil temperatures, control weeds, and improve host plant growth. Among the Tuber species, T. himalayense showed the greatest growth potential in the Korean natural environment. Additionally, a significant and positive correlation was observed between the mycelial biomass of Tuber species and the growth of inoculated seedlings, as measured by the total stem length and the number of leaves, thereby indicating the importance of symbiosis between ECM fungi and host plants. This study provides valuable insights into truffle cultivation in Korea and highlights the potential of using white mulch to promote mycelial growth, thereby contributing essential data for understanding the appropriate environmental conditions for Tuber spp. cultivation in Korea. Further study is needed to assess the long-term impact of mulching and to explore the effectiveness of other mulching materials.

Comparative Analysis of Biodegradable Mulches on Soil Bacterial Community and Pepper Cultivation

Biodegradable mulch films (BMFs) are becoming increasingly popular in agricultural practices. However, research on the ecological impact of biodegradable mulch films on pepper–soil systems is still scarce. To compare the differential effects of BMFs and polyethylene (PE) mulch on soil chemical properties, soil bacterial community composition, and pepper cultivation, a study was conducted encompassing eight distinct treatments. These treatments included three varieties of polybutylene adipate terephthalate (PBAT) combined with polylactic acid (PLA) mulches: PP-JL, PP-SD, and PP-SH; a black polypropylene carbonate mulch (PPC-BK); a brown PPC mulch (PPC-BR); a polyethylene (PE) mulch; straw mulching (NCK); and an uncovered control (PCK). After applying mulches for 129 days, most PPC and PBAT + PLA films had reached the rupture phase, whereas the PE film was still in the induction phase. Pepper yield was obviously higher in all mulched treatments (4830 kg hm−1) than in the un-mulched control (3290 kg hm−1), especially the BMF PP-JL treatment, which showed the most notable improvements in yield. Although BMF treatments maintained a lower soil temperature than the PE film mulch, they were still higher than the un-mulched control. Furthermore, the soil bacterial community composition and ecological network were not markedly affected by different mulching conditions. However, the PP-SH treatment significantly increased the abundance of Pseudomonas, Nitrosomonas, and Streptomyces genera. Moreover, Lactobacillus and Gp16 were substantially more abundant in the PPC-black (BK) and PPC-brown (BR) treatments compared to the PE mulching treatment. This study could provide valuable insights into the ecological benefits of BMFs in pepper cultivation. However, as our experiments were conducted for only one season, it is imperative to undertake long-term experiments across consecutive seasons and years for a thorough understanding and comprehensive study.

Experimental Study of Water Vapor Adsorption on Bare Soil and Gravel Surfaces in an Arid Region of Ningxia, China

Water vapor adsorption on soil, a crucial non-rainfall water resource in arid regions, warrants further experimental investigation, particularly on two typical land surfaces: bare soil and gravel. This study examined the formation characteristics and influencing factors of vapor adsorption in an arid region of Northwestern China. Observations and analyses were conducted on adsorption and evaporation measurements taken by two small weighing lysimeters (SLSs); soil temperature at a depth of 5 cm; surface temperature; relative humidity; and air temperature at a height of 30 cm above the ground from 2019 to 2020. The adsorbed water in this area was more abundant at night and less abundant during the day, with a stable nightly adsorption rate of 0.013 mm/h. Adsorption was more frequent in spring and winter (from January to June and November to December), accounting for about 90% of the total annual adsorption. In 2019 and 2020, the ratio values of adsorption to evaporation were 0.16 and 0.10 for bare soil, and 0.10 and 0.12 for gravel, respectively. Adsorption was more likely to occur when the soil moisture content was less than 13%; the highest adsorption frequency was close to 20% when the RH was between 75 and 95%; low soil temperatures were more conducive to the occurrence of adsorption. The effect of temperature differences (Ta−Ts) on adsorption was stronger than that of relative humidity. The adsorption frequency generally showed a bimodal change with increasing temperature difference, but the effect of temperature differences was less effective for gravel than bare soil. When the relative humidity was high and the temperature difference was weakly positive, the maximum adsorption intensity could reach 0.18 mm/h.

Tree lines influence soil temperatures, sward growth dynamics and litter decomposition in permanent grassland

Climate change is likely to have a negative impact on soil functions in agro-ecosystems in the future. Alley cropping combines trees and agricultural crops or grassland on the same agricultural area. It has recently been discussed as more sustainable and resilient than comparable systems without trees for the temperate zone. So far, the influence of tree lines on biomass growth and decomposition of aboveground litter in the adjacent grassland is not fully clear. We measured the effect of tree lines on soil temperatures of an adjacent grass sward at five positions differing in distance and orientation (facing the tree line in the East or West) in a temperate alley-cropping system. Growth dynamics (sward height and soil cover) as well as litter half-life times for two cutting frequencies (four vs. two annual cuts) were monitored during two experimental years. The botanical composition at the transect positions was evaluated using the dry weight rank method. We found lower soil temperatures close to the trees, even though the proportion of soil cover was slightly lower close to the trees. The sward heights did not show a consistent pattern with respect to distance to the trees. Annual biomass accumulation was greatest at 6 m distance to the trees. An intermediate distance to the trees had a beneficial effect on productivity compared to the position with the lowest tree effect (25 m). Litter half-life times decreased with increasing sward height without a consistently positive/negative influence of the tree line over the examined growth periods. Lower litter half-life times in taller grass swards indicate that the sward height is the main factor driving litter decomposition while the influence of the trees is of minor importance.

Extension of the soil monitoring network via tea bag initiatives: A 3000 km latitudinal gradient in European Russia

The increasing popularity and recognition of citizen science approaches to monitor soil health have promoted the idea to assess soil microbial decomposition based on a standard litter sample - tea bags. Although tea bag initiatives are expanding across the world, the global datasets remain biased in regard to investigating regions and biomes. This study aimed to expand the tea bag initiative to European Russia, which remains a “white spot” on the tea bag index map. We also added urban soils into the analysis, which were underestimated previously. We compared the standard and local tea brands to explore possible adaptations of the standard approach to regions with limited access to standard tea brands. The established monitoring network included natural and urban sites in six vegetation zones along a 3000 km latitudinal gradient. There was a very close linear relationship (R2 = 0.94–0.98) in the mass loss of alternative and standard tea litter. The mass loss of green tea in soil along the latitudinal gradient showed an increasing trend from north to south. Variations in the microbial decomposition of green tea were mainly explained by the latitudinal gradient, with low soil temperature identified as key factors hampering decomposition. Mass loss of the more recalcitrant rooibos tea was mainly determined via land use, with decomposition rates on average 1.3 times higher in urban soils. This pattern was in line with higher soil temperatures and pH in urban sites compared to natural counterparts. The findings of our study could prove valuable in extending the tea bag network of soil decomposition assessment into broader territories, including urban areas. Additionally, they could facilitate the involvement of citizen science and complete the database for C cycle modeling depending on climatic conditions.

Drought mitigation in sandy soil of oil palm plantation using apllication oil palm empty fruit bunch

Sandy soil in oil palm plantations has the potential to experience a higher water deficit during drought condition compared to other soil types. Application oil palm empty fruit bunch, which are co-product of oil palm industry, can be used to mitigate drought in sandy soil. This research aims to compare effective methods of applying empty fruit bunch on sandy soil in drought mitigation. This research was conducted in May-September 2023 at the Sei Rasau Region oil palm plantation of PT. BGA in Kendawangan, Ketapang, West Kalimantan. The research was carried out descriptively on block which are applied empty fruit bunch mulch (Block N21), applied focal feeder (Block P14), and applied combination mulch and focal feeder (Block P19). The technique for applying empty fruit bunch was observed directly and by seeking information from the company. Soil samples and plant vegetative data were also taken, while plant productivity was obtained from the company's secondary data. The results show that the implementation of empty oil palm fruit bunches as drought mitigation will be carried out intensively in 2022. Application empty fruit bunch as mulch are spread on the ground at a dose of 200 kg/tree and application as a focal feeder is carried out with empty fruit bunch inserted into a hole in the ground at a dose of 200 kg/hole. The microclimatic conditions in the three blocks of the research location are relatively same. The results of soil sample analysis show that soil with the application of empty fruit bunch mulch has the best soil moisture conditions and the lowest soil temperature. The lowest C/N ratio was in the combination application of mulch and focal feeder. The best plant vegetative conditions and plant productivity occurred in blocks with the application of empty fruit bunch mulch. So it can be concluded that the application of empty fruit bunch mulch provides the best drought mitigation benefits compared to the focal feeder applications and the combination application.

Karst landforms as microrefugia for soil Collembola: Open versus forested dolines

Enclosed surficial karst dolines are geomorphologically diverse habitats with the potential to strongly shape community structure and the distribution of functional groups of organisms. Forest habitats in karst landscapes are characterized by lower soil temperatures and microclimatic fluctuations compared to open habitats; therefore, they may provide favorable conditions for cold-adapted/psychrophilic species, which are highly vulnerable to climate warming. We compared the diversity and structure of soil Collembola communities at sites along microclimatic gradients in open and forested karst dolines. The effect of topography and related environmental conditions on the distribution of ecological groups of soil Collembola was analyzed, and the function of the dolines as potential climate refugia for psychrophilic arthropods was assessed. The karst dolines revealed significant habitat heterogeneity, including warm plateaus and S-facing slopes and colder and wetter bottoms and N-facing slopes. The inner sites of the dolines had an overall higher abundance and species richness compared to the plateau sites. Nonmetric multidimensional scaling ordination revealed a clear delimitation of Collembola communities in terms of warmer and cooler sites in the open dolines, while the forested dolines did not reveal such a clear pattern. The studied dolines showed a potential to serve as microrefugia in the context of global climate change. Dolines could support the long-term persistence of at least some species such as cold-adapted species. Karst dolines in the temperate zone play a key role in maintaining biodiversity; therefore, they should be central in biodiversity conservation programs.

Links between seasonal suprapermafrost groundwater, the hydrothermal change of the active layer, and river runoff in alpine permafrost watersheds

Abstract. The seasonal dynamic of the suprapermafrost groundwater significantly affects the runoff generation and confluence in permafrost basins and is a leading issue that must urgently be addressed in hydrological research in cold and alpine regions. In this study, the seasonal dynamic process of the suprapermafrost groundwater level (SGL), vertical gradient changes of soil temperature (ST), moisture content in the active layer (AL), and river level changes were analyzed at four permafrost watersheds in the Qinghai–Tibet Plateau using comparative analysis and the nonlinear correlation evaluation method. The impact of freeze–thaw processes on seasonal SGL and the links between SGL and surface runoff were also investigated. The SGL process in a hydrological year can be divided into four periods: (A) a rapid falling period (October to mid-November), (B) a stable low-water period (late November to May), (C) a rapid rising period (approximately June), and (D) a stable high-water period (July to September), which synchronously respond to seasonal variations in soil moisture and temperature in the AL. The characteristics and causes of SGL changes significantly varied during these four periods. The freeze–thaw process of the AL regulated SGL and surface runoff in permafrost watersheds. During period A, with rapid AL freezing, the ST had a dominant impact on the SGL. In period B, the AL was entirely frozen due to the stably low ST, while the SGL dropped to the lowest level with small changes. During period C, ST in the deep soil layers of AL (below 50 cm depth) significantly impacted the SGL (nonlinear correlation coefficient R2 > 0.74, P < 0.05), whereas the SGL change in the shallow soil layer (0–50 cm depth) showed a closer association with soil moisture content. Rainfall was the major cause for the stable high SGL during period D. In addition, the SGLs in periods C and D were closely linked to the retreat and flood processes of river runoff. The SGL contributed approximately 57.0 %–65.8 % of the river runoff changes in the period D. These findings will help to facilitate future hydrological research in the permafrost basins and the development and utilization of water resources in cold and alpine regions.

Are the Noah and Noah-MP land surface models accurate for frozen soil conditions?

The accurate prediction of frozen soil conditions is a critical component of dynamic terrain characterization for engineering operations in cold regions. Currently the trusted resource for dynamic terrain within the US military uses gridded global soil conditions (i.e., temperature and moisture) generated by the Land Information System (LIS) architecture. LIS combines static terrain data with trusted surface weather information into the Noah land surface model to generate a continuous representation of the global surface conditions. Both the input weather data and the model output land surface state are adjusted to match the observed state using an advanced ensemble Kalman filter data assimilation technique to incorporate in situ and remote sensing observations. While this product has been robustly evaluated under unfrozen conditions only sporadic studies have investigated its ability to accurately simulate freeze/thaw cycles, and soil temperature and moisture under frozen conditions. Here, we present a broad comparison and evaluation of the simulated soil state against an in situ network of soil temperature and moisture distributed across the Continental United States that focuses on the winter season. This comparison includes both the Noah and the newer Noah with multi-parameterization (Noah-MP) land surface models. A comparison of the two models reveals substantial differences in simulated soil moisture, frozen content, and frozen soil strength. In general, Noah predicts colder soils with deeper frost depths, and frozen soils that are slightly stronger than Noah-MP. Initial results evaluating Noah and Noah-MP against in situ observations show that both models have significantly degraded model performance for frozen soil conditions compared to their performance for unfrozen soil. In particular, Noah has a significant and persistent cold bias of approximately −3 K when the soil temperature is below freezing. This cold bias is not present in Noah-MP and further analysis shows that this improvement was almost entirely caused by a better representation of thermal conduction through snow in Noah-MP. Specifically, we find that the bulk effective thermal conductivity of a snowpack is 2× greater in Noah, which allows for greater surface heat loss during the winter and, consequently, lower soil temperatures. This analysis reveals that the more advanced multi-layer snow model in Noah-MP substantially improves the representation of soil temperature during the cold season.

The role of zinc fertilization and its interaction with nitrogen and phosphorus starter fertilization on early maize development and grain yield

The early planting of maize in temperate growing areas leads to yield and quality benefits, although a low soil temperature can affect the early nutrient uptake and delay plant development. Not only can the nitrogen (N) and phosphorus (P) uptake be limited, but that of zinc (Zn) can also be affected. Moreover, the application of N and P at early growth stages can result in an enhancement of maize growth. Two field experiment were carried out in North Italy during the 2012–14 period to: i) evaluate the most effective Zn application strategy by comparing seed, soil and foliar applications with an untreated control; ii) investigate the role of a Zn seed treatment on the early development and yield of maize grown in three different types of soils. The effect of Zn application was compared, in both experiments, to starter NP fertilization in bands at planting, according to a full factorial design. Zn fertilization significantly enhanced the early vigor and yield of the maize, although the effects were less pronounced than those of the NP fertilizer. Among the Zn fertilization strategies, maize growth was quicker for the seed and soil applications than for the foliar application or the untreated control. The former application significantly increased the plant height at stem elongation (+32%), shortened the planting-flowering period by 1 day, and increased the grain yield by 4%. Overall, the application of NP starter fertilizer shortened the planting-flowering period by 4.5 days and increased the yield by 10%, compared to the unfertilized control. In the second experiment, higher plant vigor indices were detected in all the soils for the NP starter fertilization (+22–27%) and for the Zn seed treatment (+3–9%) than in the controls. The NP starter fertilization reduced the grain moisture at harvest by 2.3% and increased grain yield by 14%, while the Zn treatment significantly increased the kernel weight but did not affect the grain yield or the moisture content. The interaction between the NP fertilization and the Zn treatment was never significant. Thus, the positive effect of Zn on the early vigor was an additional benefit to that produced by the starter NP fertilization. The study demonstrated that a Zn application at planting, with both a seed dressing and a soil treatment, significantly enhanced the early growth of different maize hybrids, in different growing seasons and soils, although the use of a NP starter fertilization led to more consistent agronomic benefits. Furthermore, the combination of NP and Zn starter fertilization resulted in a further advantage for all the considered production situations.

Plastic mulch increases dryland wheat yield and water-use productivity, while straw mulch increases soil water storage

Amplifying drought stress and high precipitation variability impair dryland wheat production. These problems can potentially be minimized by using plastic mulch (PM) or straw mulch (SM). Therefore, wheat grain yield, soil water storage, soil temperature and water-use productivity of PM and SM treatments were compared with no mulch (CK) treatment on dryland wheat over a period of eight seasons. Compared to the CK treatment, PM and SM treatments on average significantly increased grain yield by 12.6 and 10.5%, respectively. Compared to the CK treatment, SM treatment significantly decreased soil daily temperature by 0.57, 0.60 and 0.48°C for the whole seasons, growing periods and summer fallow periods, respectively. In contrast, compared to the CK treatment, PM treatment increased soil daily temperature by 0.44, 0.51 and 0.27°C for the whole seasons, growing periods and summer fallow periods, respectively. Lower soil temperature under SM allowed greater soil water storage than under PM. Soil water storage pre-seeding was 17% greater under the SM than under the PM treatment. Soil water storage post-harvest was similar for the PM and SM treatments, but evapotranspiration was 4.5% higher in the SM than in the PM treatment. Consequently, water-use productivity was 6.6% greater under PM than under the SM treatment. Therefore, PM treatment increased dryland wheat yield and water-use productivity, while straw mulch increased soil water storage.

Design of HVAC System using the Phenomena of Diurnal Temperature fluctuation

The total energy usage of the domestic sector accounts for 35.3% of total global energy consumption of this percentage, 50% is used for room and domestic HVAC systems. We worked for designing a standard module to achieve the maximum temperature difference. In this paper Diurnal Temperature Variation phenomena has been studied. The standard Simulation of the HVAC system using Diurnal Temperature Variation has been performed. The current work is a scale down model of Ground Source Heat Pump which is totally renewable in nature. This scale down model works on Diurnal temperature variation. Diurnal temperature fluctuation is the temperature difference obtained during the daytime and night time with higher and lower soil temperature. Same phenomenon is used to obtain a cooling effect and heating effect as we go deeper inside the Earth. The current work is complete replica of Ground source heat pump where the application of this phenomenon is used. Air as a flowing media is used for heat transfer between soil. The air is meant to be flown through the capillary tubes and at certain depth we get a cooling or heating effect according to atmospheric conditions. Along with that we do have to care about the human leisure requirements, for the very purpose we are also passing some amount of fresh air along with reusing the cool air inside the room by flowing it through the walls of room to provide insulation against the infiltrating heat and other elements that add temperature inside the room. It has been identified the 10.40% reduction in atmospheric air and hence it can be concluded that the geothermal HVAC system can be a sustainable and energy efficient alternative to traditional HVAC system. Also identified that the geothermal HVAC systems offer a promising solution for reducing greenhouse gas emissions and increasing energy efficiency in the building sector.