Average Daily Soil Temperature Research Articles

Responses of phenology to preseason drought and soil temperature for different land cover types on the Mongolian Plateau

Drought and heat caused major disturbance in nature by interfering with plant phenology, and can also alter the vulnerability and resilience of terrestrial ecosystems. Existing research on the Mongolian Plateau has primarily focused on studying the response of the start (SOS) and end (EOS) of the growing season to drought and heat variations. However, there is still a lack of comprehensive understanding regarding the coupled effects of drought and heat on phenology across different land cover types. In this study, we retrieved SOS and EOS based on 34-year (1982–2015) normalized difference vegetation index (NDVI) dataset from Global Inventory Modeling and Mapping Studies (GIMMS). Results showed that grasslands and the Gobi-Desert show rapid advancement in SOS, and forests presented the slowest advancement in SOS, but SOS in croplands were delayed. EOS across four land cover types advanced, with the Gobi-Desert showed the highest rate of advancement and forests the lowest. Using the Palmer Drought Severity Index (PDSI) and soil temperature as the indicators of drought and thermal conditions, the responses of SOS and EOS to these two climate variables were evaluated. The advanced SOS driven by lower drought severity was detected in forests, grasslands, croplands and the Gobi-Desert. The dominant response of EOS to drought severity was positive in croplands, grasslands and forests, except for the Gobi-Desert, where drought severity had negative effects on EOS. Compared with the daily average soil temperature (STmean), the daily maximum soil temperature (STmax, daytime), and the daily minimum soil temperature (STmin, nighttime), the daily diurnal soil temperature range (DSTR, where DSTR = STmax − STmin) between night and day were the most suitable indicators for assessing the response of SOS and EOS to soil temperature. Strong negative correlation between SOS and the preseason DSTR was pronounced in all land cover types on the Mongolian Plateau. However, EOS was negatively correlated with the preseason DSTR only in the Gobi-Desert. Last but not least, normalized sensitivity assessments reveal that the negative impacts of DSTR on SOS and EOS were the main controlling factors on the Mongolian Plateau phenology, followed by the couple negative effects of drought severity and DSTR.

Seasonal Variations in The Toughness of Leaves: A Case Study Using Griselinia Littoralis.

Potential effects of climate change include greater extremes of temperature and increased severity of storms. Many plants have evolved to resist the challenges of winter (freezing, dehydration, wind) in a process known as cold hardening. Sensing reducing temperatures, they make structural changes at the cellular level to increase their mechanical resistance and prevent damage. Previous work on this topic, though extensive, has been conducted under laboratory conditions rather than in the field and, whilst many workers have observed changes to cell wall thickness and composition, which imply increased mechanical strength, few have actually measured strength or any other parameter describing structural integrity. This paper describes experiments on a model system designed to measure the structural integrity of leaf laminae from plants growing naturally in the field over extended periods, allowing seasonal variations to be captured. Standard engineering properties-tensile strength and fracture toughness-were measured for leaves of Griselinia littoralis on nineteen separate occasions over a twelve-month period. Toughness (rather than strength) was found to be the controlling mechanical property. Toughness values were found to change significantly during the year, by more than a factor of two. Toughness correlated strongly with average daily soil temperature, but with a lag of about 1-2 weeks, suggesting that this is the time needed for structural adjustments to take place. Highest toughness values occurred in winter, confirming cold hardening. Increasing temperature in the spring was associated with decreasing toughness but in the summer when highest temperatures occurred, toughness increased again. This apparent "hot hardening" may be a response to dehydration. Results imply that a given leaf is able to both increase and decrease its toughness in response to temperature changes, demonstrating excellent plasticity of response. This case study of a single species establishes a method of reliably measuring changes in a plant's structural integrity due to cold hardening and other seasonal variations, which may be used to investigate the effects of climate change and other variables.

Short-term effect of different returning methods of maize straw on the temperature of black soil plough layer

Clarifying the effect of different maize straw returning methods on soil temperature is crucial for optimizing the management of farmland straw and the efficient utilization of heat resources in the black soil region of Northeast China. To investigate the impacts of straw returning methods on soil temperature, we conducted a field experiment with four treatments during 2018 and 2020, including plough tillage with straw returning (PTSR), rotary tillage with straw returning (RTSR), no-tillage with straw returning (NTSR), and a control treatment of conventional ridge tillage without straw returning (CT). We measured soil temperature and water content at the 5 cm, 15 cm and 30 cm soil layer, and the straw coverage rate during the 3-year maize growth period. We further analyzed the differences of soil temperature in different soil layer under different treatments, accumulated soil temperature and growing degree-days (GDD) above 10 ℃, daily dynamics of soil temperature, the production efficiency of air accumulated temperature among different treatments, and explored factors causing the difference of soil temperature and the production efficiency of air accumulated temperature. Our results showed that different treatments mainly affected soil temperature from the sowing to emergence stage (S-VE) of maize. The daily average soil temperature showed a trend of CT>PTSR>RTSR>NTSR. The differences of soil temperature under different treatments showed a decreasing trend as growth process advanced and soil depth increased. Compared with the CT treatment, soil temperature at 5 cm depth was decreased by 0.86, 1.84 and 3.50 ℃ for PTSR, RTSR, and NTSR treatments, respectively. NTSR significantly reduced the accumulated temperature of ≥10 ℃ in different soil layers and GDD. The accumulated temperature ≥ 10 ℃ at the 5, 15, and 30 cm soil layers decreased by 216.2, 222.7, and 165.1 ℃·d, and the GDD decreased by 201.9, 138.7 and 123.9 ℃·d, respectively. In addition, production efficiency of air accumulated temperature decreased by 9.7% to 15.6% for NTSR. Conclusively, PTSR and RTSR had significant impacts on topsoil temperature during the maize growing period from sowing to emergence, but did not affect the accumulated soil temperature and the production efficiency of air accumulated temperature. However, NTSR significantly reduced topsoil temperature and production efficiency of air accumulated temperature.

Evaluation of carbon sink in the Taklimakan Desert based on correction of abnormal negative CO2 flux of IRGASON

Studies showing that deserts can sequester CO2 through non-photosynthetic processes have contributed to locating missing carbon sinks. However, the contradiction between the desert CO2 flux obtained by different observation methods leads to uncertainty in evaluating desert carbon sequestration. This has caused scepticism regarding desert carbon sequestration after years of research. Through a comparative experiment in the non-vegetated shifting sand of the Taklimakan Desert (TD), it was found that if the abnormal negative CO2 flux observed by IRGASON during the day was not corrected, the carbon sequestration of the TD would be overestimated. The CO2 flux observed by EC155 is highly consistent with that of LI-COR8100A and can reflect the real CO2 exchange in the desert. The CO2 flux observed by EC155 was used to correct the results of IRGASON. Results show that the expansion/contraction of soil air containing CO2 caused by the change in the daily average soil temperature difference (T0-10cm) drives CO2 exchange in shifting sand. This results in diurnal variation of CO2 release caused by shifting sand during the day and CO2 absorption at night, and a unimodal distribution of CO2 exchange caused by shifting sand throughout the year. From April to September (T0-10cm > 2 °C), the shifting sand releases CO2 as a carbon source. In the other months (T0-10cm < 2 °C), the shifting sand absorbs CO2 as a carbon sink. The stronger absorption shows that the shifting sand in the TD provides carbon sequestration, with a CO2 uptake rate of ~148.85 × 104 tons a-1. This suggests that deserts play an active role in locating the missing carbon sinks and mitigating climate change, and that the status of deserts in the global carbon cycle cannot be ignored.

The Impact of Insect-Proof Screen on Microclimate, Reference Evapotranspiration and Growth of Chinese Flowering Cabbage in Arid and Semi-Arid Region

Despite the steadily increasing area under protected agriculture there is a current lack of knowledge about the effects of the insect-proof screen (IPS) on microclimate and crop water requirements in arid and semi-arid regions. Field experiments were conducted in two crop cycles in Ningxia of Northwest China to study the impact of IPS on microclimate, reference evapotranspiration (ET0) and growth of Chinese Flowering Cabbage (CFC). The results showed that IPS could appreciably improve the microclimate of the CFC field in the two crop cycles. During the first crop cycle (C1), compared with no insect-proof screen (NIPS) treatment, the total solar radiation and daily wind speed under the IPS treatment were reduced by 5.73% and 88.73%. IPS increased the daily average air humidity, air, and soil temperature during C1 by 11.84%, 15.11% and 10.37%, respectively. Furthermore, the total solar radiation and daily wind speed under the IPS treatment during the second crop cycle (C2) were markedly decreased by 20.45% and 95.73%, respectively. During C2, the daily average air temperature and air humidity under the IPS treatment were increased slightly, whereas the daily average soil temperature was decreased by 4.84%. Compared with NIPS treatment, the ET0 under the IPS treatment during C1 and C2 was decreased by 6.52% and 21.20%, respectively, suggesting it had great water-saving potential when using IPS. The plant height, leaf number and leaf circumference of CFC under the IPS treatment were higher than those under the NIPS treatment. The yield under the IPS treatment was significantly increased by 36.00% and 108.92% in C1 and C2, respectively. Moreover, irrigation water use efficiency (IWUE) was significantly improved under the IPS treatment in the two crop cycles. Therefore, it is concluded that IPS can improve microclimate, reduce ET0, and increase crop yield and IWUE in arid and semi-arid areas of Northwest China.

Effects of heat waves on soil temperatures in Slovenia

Soil temperature regulates the rate of plant growth and tells us much about the climatic characteristics of a particular site. Climate variability and extremes need to be studied and there is a large gap in knowledge about soil temperature during heat waves. Agricultural land is highly dependent on heat waves, which are becoming longer, more intense and more frequent, and it is important to monitor soil temperatures in situ to understand their changes during heat waves. Therefore, the aim of this work was to investigate how soil temperatures change at different depths during and after heat waves. Average daily air and soil temperature data for the 25-year period 1992-2016 were evaluated at four agrometeorological stations in three climate zones in Slovenia and analyzed during heat waves determined according to the Slovenian definition. During the period 1992-2016, 53 (Lesce) to 76 (Ljubljana) heat waves were identified. Analysis of average air and soil temperatures before, during and after heat waves showed higher responsiveness of the upper part of the soils and an increase in the time lag between maximum air temperature and maximum soil temperature with depth. The maximum temperature during the heat wave was reached on average in three to nine days, depending on the depth. Only in Moderate climate of the hilly region, the average daily temperatures at a depth of 100 cm remained below 20°C during and after the heat wave. The temperature rise in the deeper layers of the soil lasts longer than in the shallower layers.

White Plastic and Deficit Irrigation Improve Pomegranate Production

ABSTRACT Developing improved water management strategies and on-farm cultural practices are important in reducing pomegranate (Punica granatum L. cv Wonderful) production costs. A pomegranate orchard established in 2010 was irrigated at water replacement rates of 35, 50 and 100% of crop evapotranspiration from 2013 to 2016. A durable white plastic tarp was installed in one half of each water replacement plot to evaluate the added benefits to soil moisture retention, weed control, and plant growth and yield. Edaphic orchard floor conditions such as light reflectance into the lower tree canopy, mid-day soil surface temperature, soil water content, and average daily soil temperatures were moderated or improved by the plastic cover. Phenological changes such as leaf greenness, trunk basal suckering, and trunk diameter were generally enhanced by increased water application rates and plastic use. Marketable and total fruit yields increased by an average of 20 to 29% from 2013 to 2016 with the use of plastic cover compared to bare soil. Total fruit yield increased linearly with increasing water replacement rates. Neither the white plastic nor irrigation rates improved external fruit color. Fruit raw product attributes were little changed by treatments. The research clearly demonstrated the benefit of plastic cover on improving pomegranate production.

К ВОПРОСУ ИЗУЧЕНИЯ ТЕМПЕРАТУРНОГО РЕЖИМА ПОЧВ ЗАПОВЕДНИКА «БАСТАК» НА ОСНОВЕ ИСПОЛЬЗОВАНИЯ ПРОФЕССИОНАЛЬНОЙ МЕТЕОСТАНЦИИ «СОКОЛ-М»

The paper presents the experience of using data on soil temperature obtained with the help of a professional weather station «Sokol-M» in the Bastak nature reserve. The author has made the analysis of average daily air and soil temperature indicators at different depths. The process of heat propagation deep into the soil is observed, due to the absence of negative soil temperatures at a depth of 25 cm, with negative indicators in the upper 10 cm of the soil profile.

Clarification of the necessary meteorological conditions to control Ralstonia solanacearum via soil solarization

The present study was conducted to investigate the relationships between meteorological conditions and the disinfection effect of soil solarization in five greenhouses (located in Kaizu City, Gifu, Japan). The specific analysis focused on soil temperature, the population density of Ralstonia solanacearum before and after soil disinfection, the air temperature inside and outside the greenhouse, the amount of solar radiation, and rainfall. The density of R. solanacearum decreased markedly after soil solarization with the average daily soil temperature exceeded 40 °C for 10 consecutive days or more. In the scope of this study, the meteorological conditions required to meet this condition included: a disinfection period of 24 days or more, an average daily air temperature above 28.0 °C, as well as average daily solar radiation exceeding 17.0 MJ m−2. Moreover, with the average daily soil temperature of the soil surface layers exceeded 40 °C for 10 consecutive days or more, the average daily air temperature and average daily solar radiation should be higher than 29.3 °C and 20.2 MJ m−2, respectively. If the mentioned meteorological conditions were met, a fairly good disinfection effect could be achieved. However, if the greenhouse was poorly insulated, or if the solar radiation and air temperature decreased significantly in rainy and cloudy days, the soil was not likely to reach 40 °C or more for 10 consecutive days.

Estimation of Thermal Diffusivity for Greenhouse Soil Temperature Simulation

In greenhouse energy balance models, the soil thermal parameters are important for evaluating the heat transfer between the greenhouse air and the soil. In this study, the soil thermal diffusivity was estimated from greenhouse soil temperature data using the amplitude, phase-shift, arctangent, logarithmic, and min-max methods. The results showed that the amplitude method and the min-max method performed well in estimating the soil thermal diffusivity. The obtained soil thermal diffusivity was input into a sinusoidal model to determine the greenhouse soil temperature at different soil depths. For greenhouse applications, the daily average soil temperature at different depths was predicted according to the temperature at the surface and the annual mean soil temperature. The model was validated using soil temperature data from summer and winter, when the greenhouse was cooled and heated, respectively.

Burning and mowing similarly increase prairie plant production in the spring, but not due to increased soil temperatures

AbstractBurning and mowing are two of the most common grassland disturbances across millions of hectares worldwide, but uncertainty remains about when and why these disturbances increase plant production. One of the main hypotheses for increased plant production is that disturbances increase soil temperature in the early growing season and thereby increase plant growth. I tested this hypothesis using a multi‐decade study of the frequency (annual or quadrennial) and season (spring, summer, or autumn) of reconstructed tallgrass prairie burning and mowing. To determine plant production, I measured aboveground biomass during three periods of the 2015 growing season: (1) prior to mid‐May; (2) mid‐May to early July; and (3) early July to the end of the growing season in late September. I also measured soil temperatures from May 2014 to January 2016. This unique dataset allows a detailed picture of when burning and mowing are increasing plant production and whether these increases are likely caused by soil temperatures. I found that, compared to other treatments, autumn burning and mowing similarly increased plant production from the beginning of the growing season to mid‐May (autumn disturbances increased production from 37 to 77 g/m2) and, compared to other treatments, both autumn and spring burning and mowing similarly increased plant production from mid‐May to early July (autumn and spring disturbances increased production from 363 to 439 g/m2). Mowing had little effect on soil temperature but burning increased average daily maximum soil temperature at 2.5 cm depth by 6.4°C in the month after burning. Overall, these results suggest that burning did not increase early growing season plant production due to increased soil temperature, given that mowing similarly affected plant production but did not similarly affect soil temperature. I explore alternate explanations for changes in plant production, including increased light and nutrient availability, and decreased detritus.

Resilience of bacteria, archaea, fungi and N-cycling microbial guilds under plough and conservation tillage, to agricultural drought

Climate change causes droughts, which in turn cause significant physiological stress for soil microorganisms. In this study, we investigated how the abundance of total bacterial, crenarchaeal and fungal communities and the abundance of N-cycling microbial guilds responded to a severe agricultural drought event in a long-term experiment of minimum tillage (MT) and conventional ploughing (CT) at two soil depths. Drought, defined as a reduction of soil water content and increased soil temperature, significantly decreased the abundance of all the studied microbial communities. The data showed linear relationships between all dependent variables and soil water content and soil temperature for the examined range of soil water content (WHC 13–76%) and examined range of average daily soil temperature at 5 cm depth (17–30 °C). Thus, we found that the abundance of most studied microbial communities decreased by about 2% when water content decreased by 1 mass % and by about 10% when temperature increases by 1 °C. When comparing communities at average soil water content and average soil temperature, MT had higher average abundances of total bacterial and crenarchaeal 16S rRNA and fungal ITS genes in the 0–10 cm soil layer than did CT (1.9, 2.9 and 2.5 times, respectively), as well as AOA and AOB amoA (3.9 and 1.7 times, respectively), nirK, nirS, nosZI and nosZII genes (2.0, 1.8, 1.8 and 2.3 times, respectively); while significant differences between MT and CT in the 10–20 cm soil layer were found only in the average abundance of crenarchaeal 16S rRNA and crenarchaeal amoA genes (3.5 and 2.7 times greater under MT than CT). Regardless of the weather conditions during our study, the abundances of all communities were greater under MT 0–10 than under CT 0–10. After three weeks of severe drought, the greatest decrease in the abundance of all communities, bacterial and archaeal N-cycling guilds as well as total prokaryotes and fungi, was observed under MT 0–10. However, after only a few rainfall events, all communities under both tillage systems reached their initial abundance, demonstrating a high resilience.

Soil Warming Increases Arsenic Availability in the Rice Rhizosphere

Core Ideas Arsenic is a common contaminant in rice, threatening yield and human health. Climate warming could alter availability and plant uptake of arsenic. Arsenic concentrations in porewater and plant tissue increased with soil warming. Grain arsenic concentrations were not significantly affected by soil temperature. Future studies should explore links between climate conditions and arsenic uptake by rice. Arsenic uptake by rice (Oryza sativa L.) threatens yield and contaminates grain. Climate warming could affect these hazards. We tested the effect of elevated soil temperature on arsenic availability to and uptake by rice plants. Rice was grown in arsenic‐amended soil in rhizoboxes that facilitated porewater sampling and synchrotron X‐ray fluorescence (XRF) imaging of the rhizosphere. Plants were subjected to similar atmospheric conditions but different soil temperatures. The XRF imaging revealed greater arsenic sequestration in root iron plaques with a warmer soil temperature. Mean and median arsenic concentrations in porewater and root, straw, and husk tissue were positively correlated with average daily maximum soil temperature. Grain arsenic concentrations did not change. Warmer soil temperatures likely increased plant‐available arsenic by increasing reductive dissolution of arsenic‐bearing iron minerals, but the plants effectively regulated grain arsenic. The impacts of changing environmental conditions on arsenic contamination of rice should be further explored.

Maize (Zea mays L.) yield and soil properties as affected by no tillage in the black soils of China

A four-year tillage experiment on maize was conducted in the high latitude region of Northeast of China. The main objective of this study was to investigate the effects of different field tillage practices on maize grain yield, soil physical properties, and soil water and temperature dynamics in Northeast of China. The tillage practices included moldboard plow tillage (MOT), rotary tillage (ROT), reduced tillage (RET), combined tillage (COT), and no tillage (NOT). The surface soil water content at depths of 0–20 cm was higher under NOT compared with other tillage practices, but not different at the deeper soil depths in 2011. The soil temperatures under NOT and RET were lower than those under moldboard plow tillage and ROT at depths of 5 and 15 cm, respectively, measured at 9:00 am in 2005. From the hourly dynamics of soil temperature, the differences among the tillage practices mainly appeared during the daytime (from 8:00 am to 7:00 pm). Among all the practices, the average daily soil temperature under ROT was the highest, while that under NOT was the lowest. MOT, ROT, and RET had higher soil accumulative infiltration compared with NOT and COT. The surface soil bulk density under NOT was higher than or equal to that under the other four tillage practices. The maize yields under NOT were the lowest among all the tillage practices for three years straight. Meanwhile, the yields under MOT were the highest, which were about 47%, 61%, and 38% higher than those under NOT. NOT practice is not recommended for use in spring-planted maize under the high latitude humid cool climate Mollisol region in Northeast of China.

Improved yield by harvesting water with ridges and subgrooves using buried and surface plastic mulchs in a semiarid area of China

This paper determines the responses of soil temperature, water status and crop yields to a new planting pattern involving ridges and subgrooves with plastic film mulching in a millet-field pea-spring wheat-potato cropping system. The study was conducted in a typical semiarid area, during the four annual growing seasons of 2005–2008 and five treatments were designed: (1) a flat plot with no mulching, which is the conventional tillage practice (CK); (2) alternating ridges and furrows with no mulching (M0C0); (3) alternating ridges and furrows with no mulching, and subgrooves mulched with plastic film (M0C); (4) alternating ridges and furrows, with only the ridges mulched with plastic film on the surface (MC0); and (5) alternating ridges and furrows, as well as subgrooves, with the ridges and subgrooves mulched with plastic film (MC). The subgrooves with plastic film mulching increased topsoil temperature, the average daily soil temperature of the 4-growing seasons was 16.7, 16.8, 16.9, 17.4 and 17.2°C for the CK, M0C0, MC0, M0C and MC, respectively. The soil temperature was significantly higher in the M0C and MC than in the CK, M0C0 and MC0 in May 2006, September in 2007 and May 2008. In average and wet years, the soil water content in the 20–40cm soil layer was 6.2–37.7% higher in the MC than in the CK. The ridges and subgrooves with plastic film mulching improved crop yields, and the average yield over the four years was higher in the MC than in the CK, M0C0, M0C and MC0 by 163%, 98%, 62% and 21%, respectively. Potato is a staple and economic crop in this region, and the ratio of large and moderate-sized potato tuber yield to total tuber yield was 21.7% higher in the treatments with subgrooves than in the treatments without subgrooves. In conclusion, the technique of ridges and subgrooves with plastic film mulching is an effective practice for improving crop yields in semiarid agroecosystems.

Soil Solarization in High Tunnels in the Semiarid Southwestern United States

High tunnels are unheated structures covered with polyethylene (PE) glazing to protect high-value crops from adverse weather. The objective of this study was to raise soil temperatures to determine the efficacy of soil solarization using clear mulch on the soil surface and glazing or no glazing on a high tunnel during the hottest months of the year in the semiarid southwestern United States. Solarization trials were conducted in May and June 2013 in two high tunnels in southern Arizona. Highest soil temperatures were reached with the combination of a high tunnel covered with glazing and the soil covered with PE mulch. Average daily soil temperatures were 48 and 47 °C and average degree hours (DH) per day (base temperature 45 °C) were over 14 at soil depths of 5 and 15 cm. The average daily maximum soil temperature at 5- and 15-cm depth was 63.4 and 52 °C, respectively. The second highest soil temperatures were reached when the soil was covered with PE mulch without high tunnel glazing, which resulted per day in 5.2 DH above 45 °C at 5 cm and less than one DH at 15-cm depth. Glazing on the high tunnel without covering the soil surface raised soil temperatures only at the 5-cm depth above 45 °C, but not further down. High tunnel producers in the low desert areas in the southwestern United States can complete solarization in less than 1 week, depending on the organism to be controlled, when the soil is fallow during the summer months with glazing on the high tunnel and on the soil surface.

Improved reconstruction of soil thermal field using two-depth measurements of soil temperature

• An improved method was proposed to reconstruct soil thermal field. • A higher accuracy was achieved by the improved method. • Two-depth soil temperatures with optional air temperatures are the only input. The accurate estimation of soil thermal field is crucially important because soil temperature is a key parameter widely used in many related fields. This paper proposed an improved heat-conduction-equation (HCE) method to reconstruct soil thermal field using two-depth measurements of soil temperature. The revised HCE method employed a direct approach as well as an indirect approach to estimate both the daily average soil temperature (DST) and the instantaneous soil temperature (IST), during which the annual temperature cycle and the diurnal temperature cycle are combined. Two validation experiments (i.e., Test-1 and Test-2) were performed with soil temperature measurements at five stations chosen from the Soil Climate Analysis Network (SCAN). The results show that the revised HCE method improves the accuracy of modeling soil thermal field in comparison to its traditional form. The root mean square errors (RMSEs) of the ISTs estimated by the traditional HCE method range from 1.0 to 2.1 °C (2.4 to 4.8 °C) in Test-1 (Test-2); while the errors of the revised HCE method by the indirect approach are reduced to less than 1.0 °C in both Test-1 and Test-2; the errors by the direct approach are further reduced to less than 0.7 °C in both Test-1 and Test-2. The improved method has further potential to estimate soil heat flux, a variable that can be inferred using soil temperature gradients associated with soil apparent thermal conductivity .

Effect of Ground Covers on Soil Temperature in Urban and Rural Areas

Human activity has changed land surfaces by converting native ecosystems to urban land uses, which has caused increases in soil temperature. In order to understand the effect of different ground covers on soil temperature, observation stations were built under concrete, bare soil, and grass ground covers located in urban and rural areas of Nanjing City, China. By analyzing continuously recorded soil temperature data from June 2009 to June 2010, it was found that the average daily soil temperature in both urban and rural areas shows a tendency of concrete > bare soil > grass ground cover. Soil temperature under concrete ground cover in summer is significantly higher than that under bare soil and grass, consistent with the urban heat island effect. The cover thermal-physical properties and soil structures lead to differences in soil temperature between urban and rural areas. As compared to bare or grass-covered soils, concrete-covered soils exhibit lower values of evaporation rate, reflectivity, and specific heat capacity and higher values of thermal conductivity. As such, the initial heating rate of the soil under concrete ground cover is faster, and the final temperature is higher. These findings provide a basis with which to reduce the heat island effect through the provision of increasing grass-covered open space.

Effects of plastic covering methods on the growth and yield of potatoes in winter fallow rice fields in Hunan

Favorita, a breed of potato was selected as a test material to compare its growth and yield under four different cultivation circumstances in winter fallow rice fields, they are plastic mulching, arch plastic mulching,plastic mulching plus arch plastic mulching( also called double films mulching) and non-mulching. The results showed that the daily average soil temperature with double films mulching was highest, higher than that of plastic mulching, arch plastic mulching and non-mulching 0.33, 1.93, 2.89 ℃, respectively. Therefore, potatoes cultivated with double films mulching was the first one in seedling sprout, which was earlier 4, 21, 31 d than those of cultivated with plastic mulching, arch plastic mulching and non-mulching, respectively. Although the plant height of potatoes cultivated with plastic mulching was higher than that of potatoes cultivated with non-mulching significantly,the stem diameter and main stem number were significantly less than that of potatoes cultivated in non-mulching.Double films mulching cultivation could improve total yield and market needed tuber yield, with 31.18 and 28.54ton per hectare respectively. And the next were cultivated in arch plastic mulching and plastic mulching cultivation in turn, which were significantly higher than that of potatoes cultivated with non-mulching. The profit of double films mulching cultivation was the highest with 12.22 thousand CNY per hectare.

Moderate Warming in Microcosm Experiment Does Not Affect Microbial Communities in Temperate Vineyard Soils

Changes in the soil microbial community structure can lead to dramatic changes in the soil ecosystem. Temperature, which is projected to increase with climate change, is commonly assumed to affect microbial communities, but its effects on agricultural soils are not fully understood. We collected soil samples from six vineyards characterised by a difference of about 2 °C in daily soil temperature over the year and simulated in a microcosm experiment different temperature regimes over a period of 1 year: seasonal fluctuations in soil temperature based on the average daily soil temperature measured in the field; soil temperature warming (2 °C above the normal seasonal temperatures); and constant temperatures normally registered in these temperate soils in winter (3 °C) and in summer (20 °C). Changes in the soil bacterial and fungal community structures were analysed by automated ribosomal intergenic spacer analysis (ARISA). We did not find any effect of warming on soil bacterial and fungal communities, while stable temperatures affected the fungal more than the bacterial communities, although this effect was soil dependent. The soil bacterial community exhibited soil-dependent seasonal fluctuations, while the fungal community was mainly stable. Each soil harbours different microbial communities that respond differently to seasonal temperature fluctuations; therefore, any generalization regarding the effect of climate change on soil communities should be made carefully.