Soil Temperature Depth Research Articles

Variability of soil thermal diffusivity in three Iowa fields

AbstractSoil thermal properties influence the rates of chemical and biological reactions in the soil, seed germination, crop establishment, and productivity. Soil temperature varies with time and depth, and thermal diffusivity (α) is the main property associated with soil temperature variations. Variations in α within row‐cropped fields under long‐term tillage practices are not well documented in Iowa fields. The objective of this study is to determine α variations within three central Iowa fields under long‐term tillage practices and to estimate the required number of measurement sites within each field to determine α at a specified precision. Each field receives different tillage operations; one field is fall moldboard plowed followed by spring disking (MP), another field is fall chisel plowed followed by spring disking (CP), and the third field is ridge no‐tilled (RN) slot planted. Thermocouples are used to measure soil temperature at two depths, that is, 1 and 10 cm, at 49 locations (49 grid locations; 1.5 m × 3 m) in each of three adjacent fields. After allowing the thermocouples to equilibrate with the soil environment for 2 weeks in each field, hourly 1‐ and 10‐cm depth soil temperature observations were recorded for a separate 24‐h period in each field following rainfall events. Soil temperature measurements with the amplitude and phase equations were analyzed, and 49 α values were determined in each field. The larger the bulk density, the larger the thermal diffusivity. MP had the largest α values, while CP had the lowest values. The mean and standard deviation values for α in the MP, CP, and RN fields were 23 ± 4.8, 13 ± 2.2, and 21 ± 4.0 cm2 h−1, respectively. The coefficients of variation were similar for the three fields, ranging from 17% to 21%. The minimum number of samples needed to obtain a confidence interval of 7 cm2 h−1 for α was two, five, and seven, respectively, for the CP, RN, and MP fields. The MP field had the largest mean α value and required the largest number of samples to determine α at a specified precision.

No-tillage with straw mulching promotes wheat production via regulating soil drying-wetting status and reducing soil-air temperature variation at arid regions

Straw returning is a technical measure of crop production widely adopted in arid and water-deficient areas. However, the mechanism by which straw returning drives spatio-temporal changes in soil moisture and temperature to improve crop productivity remains unclear. So, a three-year field experiment was conducted with four various straw returning treatments for wheat production: 1) no-tillage with straw mulching (NTSM), 2) no-tillage with straw standing (NTSS), 3) conventional tillage with straw incorporation (CTS), and 4) conventional tillage without straw returning (CT, control). The spatio-temporal variations of soil moisture content and soil temperature were assessed. It will provide the basis for selecting the appropriate way of straw returning to increase wheat yield and clarifying its hydrothermal regulation mechanism. NTSM and NTSS were effective in maintaining soil moisture and regulating soil temperature, and had a greater effect on grain increase, than CTS and CT. Meanwhile, NTSM had a relatively higher yield than NTSS through better regulation of soil hydrothermal characteristics. NTSM had higher soil moisture content in the 0–120 cm depth by 9.8–10.2%, 6.7–8.2%, 6.5–10.2%, and 6.9–7.4% at sowing to jointing, jointing to booting, booting to early-filling, and early-filling to maturing stages of wheat, respectively. NTSM decreased evapotranspiration modulus coefficient (ETMC) and evapotranspiration intensity (ETI) at jointing to early-filling stage of wheat, but increased both indexes from early-filing to maturing stage of wheat, which is helpful to adjust the contradiction of soil moisture demand for wheat in different growth stages. Additionally, NTSM had 9.8–10.2%, 6.7–8.2%, 6.5–10.2%, and 6.9–7.4% lower soil temperature in the 5–25 cm depth than CT, at the four aforementioned wheat growth stages, respectively. The difference of soil temperature was mainly reflected at the 5–15 cm depth by analyzing the difference on soil temperature in various soil depths. The treatment on NTSM had little variation and stabilized soil temperature, according to the difference between air and average soil temperature of 5–15 cm depth. NTSM allowed wheat to grow a suitable thermal environment across their growth period, which is a significant regulatory mechanism for wheat to maintain better growth and development. Thereby, NTSM boosted wheat grain yield by 18.6–27.3% as compared to CT. Collectively, the NTSM treatment had better effect on regulating soil drying-wetting status and reducing soil-air temperature variation, which could be used as a recommended measure to improve wheat productivity at arid conditions.

A dataset of meteorological observations at Zhejiang Tiantong National Forest Ecosystem Observation and Research Station (2003 – 2017)

Evergreen broad-leaved forests are one of the main types of Chinese forests. The meteorological data of them are of great value for the study on the function and ecological process of evergreen broad-leaved forest ecosystem, and can serve as a major data source for weather forecast and disaster warning. Zhejiang Tiantong National Forest Ecosystem Observation and Research Station located in the subtropical broad-leaved evergreen forest in Tiantong Forest Park in eastern China. Since April 2003, we had collected long-term meteorological data by setting up the automatic meteorological observation system. This dataset contains the monthly data (177 entries) and annual data (15 entries) from 2013 to 2017, including 18 meteorological observation indexes, such as atmospheric temperature, atmospheric humidity, precipitation, atmospheric pressure, total radiation, net radiation, reflected radiation, UV radiation, photosynthetically active radiation, sunshine hours and soil temperature in different depths (0 cm, 5 cm, 10 cm, 15 cm, 20 cm, 40 cm, 60 cm and 100 cm). It is expected to provide data support for studying the ecological process, evaluating ecosystem service function and increasing disaster warning accuracy of local forests in Tiantong zone.

Response of Soil Respiration Rates to Soil Temperature and Moisture at Different Soil Depths of Caragana korshinskii Plantation in the Loess-Hilly Region

It is of great significance to clarify the influence of soil temperature and moisture on soil respiration rate and its characteristics in ecologically fragile regions under the background of climate change for the accurate assessment and prediction of carbon budgets in this region. The average CO2 concentration and soil temperature and moisture at different soil depths (10, 50, and 100 cm) were measured using a CO2 analyzer and temperature and moisture sensors. The soil respiration rate was calculated using Fick's first diffusion coefficient method. The dynamic characteristics of soil temperature, soil moisture, and soil respiration rate in different soil depths were explored, and the response of soil respiration rate to soil temperature and moisture were further analyzed. The results showed that the diurnal variation in soil respiration rate decreased significantly with the increase in soil depth (P<0.05), and the peak time lagged behind. Soil respiration rate in adjacent soil depths (10, 50, and 100 cm) lagged 1 h from top to bottom. The monthly variation in soil respiration rate was a multi-peak curve, in which the maximum soil respiration rates of 10, 50, and 100 cm soil depths were on July 25th, August 6th, and August 10th, reaching 13.96, 2.96, and 1.47 μmol·(m2·s)-1, respectively. The effect of soil temperature on soil respiration rate decreased with the increase in soil depth. Soil temperature at 50 cm and below had no significant effect on soil respiration rate (P>0.05). The fitting index of 10 cm soil depth was the best (R2=0.96), but the fitting indexes of 50 cm and 100 cm soil depths were poor (R2=0.00 and R2=0.01, respectively). The temperature sensitivity coefficient Q10 decreased with the increase in soil depth. Soil moisture in different soil depths had significant effects on soil respiration rate (P<0.05), and the quadratic fitting indicated that 50 cm (R2=0.35)>10 cm (R2=0.22)>100 cm (R2=0.31). The combined effects of soil temperature and moisture in different soil depths could explain 96%, 6%-50%, and 22%-24% of soil respiration rate, respectively. In summary, the effects of soil temperature and moisture at different soil depths of the Caragana korshinskii plantation in the loess-hilly region on soil respiration rate differed. The soil respiration rate of the 10 cm soil depth was affected by the comprehensive effect of soil temperature and moisture; however, the relative contribution of soil temperature was higher, and soil moisture at and below a soil depth of 50 cm was the key factor. These results could help improve predictions on the impact of future climate change on the carbon cycle of terrestrial ecosystems in the region and provide a theoretical basis for greenhouse gas regulation in the future.

The Influence of N2O Emission to Water and Nitrogen Coupling Mechanism in Black Soil under Drip Irrigation Mode

This experiment is aimed at revealing the main characteristics of N2O emission from soybean in black soil and clarifying the relationship between N2O emission and environmental factors; in this experiment, static chamber-gas chromatography field observation method was used; meanwhile, three different drip irrigation amounts (300 mm, 350 mm, and 400 mm) and five different nitrogen application amounts (0, 63, 72, 81, and 90 kg/hm2) were set up to study the effects of different coupling modes on soybean N2O emission and the relationship between N2O emission and environmental factors. The results showed that the peak value of N2O emission flux of soybean mainly occurred in July and August, and the amount of N2O emission flux in each growth period was flowering-podding period &gt; branching period &gt; seedling period &gt; grain filling period. N2O emission increased with the increase of drip irrigation amount and nitrogen application amount. The effects of drip irrigation and nitrogen application on N2O emission were significantly different. Under the three drip irrigation modes, the N2O emission fluxes of most treatments were significantly correlated with the temperature in that day, and the soil temperature in different soil depths was significantly correlated with the N2O emission fluxes. The correlation relationship between the temperature of each soil layer under drip irrigation 300 mm and N2O emission fluxes was less than that under drip irrigation 350 mm and drip irrigation 400 mm. There was no significant correlation between N2O emission flux and NH4+-N and NO3-N, and there was no significant correlation between N2O cumulative emission and dry matter quality in the aboveground part of soybean. It shows that the emission of N2O itself is affected by multiple environmental factors and shows certain randomness. The research results can provide important theoretical basis and technical support for realizing nitrogen reduction and efficient utilization of soybean water and fertilizer in the black soil region of northeastern part of China.

Simulations and Experiments of Soil Temperature Distribution after 2.45 GHz Long-Term Microwave Treatment

Soil disinfection is an important agronomic measure to prevent soil-borne diseases, insects, weeds and other hazards. Based on the premise of being environmentally friendly, microwave soil disinfection can improve crop yield and quality in a pollution-free, residue-free and green way. The law of microwave soil heating is the theoretical basis of microwave soil disinfection. Therefore, in this paper, loess soil of North China and black soil of Northeast China are used as test materials to explore the law of soil heating under the action of microwaves. First, COMSOL Multiphysics software was used to simulate the temperature field change in the microwave-irradiated soil, and a simulation model of the temperature field of the microwave-irradiated soil was constructed to analyze the effective working range and temperature distribution characteristics of the microwave-irradiated soil. Second, using the 2.45 GHz microwave treatment, the following conditions were tested: soil moisture conditions of 10%, 15%, 20% and 23% (within the natural moisture content range). The loess and black soil were treated by microwave irradiation for 1~12 min, respectively (1 min/time increment). A single-factor experiment was designed to explore the influence of these factors on the soil heating law. The results show that the two soil surface temperatures are positively correlated with the soil moisture content, both of which satisfy Tsurface23% &gt; Tsurface20% &gt; Tsurface15% &gt; Tsurface10%, and the surface temperature of black soil is higher than that of loess. According to the experimental results of the internal temperature distribution of loess and black soil irradiated by microwaves, the surface equations of “irradiation time–soil depth-soil temperature” and “irradiation time–soil moisture content–soil temperature” were constructed by surface fitting. When the irradiation time and moisture conditions are the same, the average temperature inside the irradiation area satisfies T¯α black soil &gt; T¯α loess. The results of long-term microwave soil heating preliminarily confirmed the feasibility of microwave soil disinfection and the optimal conditions of microwave irradiation in loess of North China and Northeast black soil, which provides a certain reference for the study of soil-borne diseases inactivation at high temperature.

Evaluation and analysis of SMAP, AMSR2 and MEaSUREs freeze/thaw products in China

The surface seasonal freeze/thaw (F/T) signal detected by passive microwave remote sensing is very important for the water cycle, carbon cycle and climate change research. In this study, we evaluated and analyzed the Soil Moisture Active Passive (SMAP) L3 F/T product, Advanced Microwave Scanning Radiometer 2 (AMSR2) F/T product and Making Earth System Data Records for Use in Research Environments (MEaSUREs) F/T product over different regions in China, including the Genhe area in Northeast China, the Saihanba area in North China, and the Qinghai-Tibet Plateau (QTP) area. The overall accuracy of F/T products assessed with the 5 cm depth soil temperature is 90.38% for SMAP, 90.23% for AMSR2 and 84.73% for MEaSUREs in cold and humid temperate forest climates and the plateau continental climate area (Genhe, Tianjun, and Qumalai) where permafrost is distributed, and 76.64% for SMAP, 83.67% for AMSR2 and 77.37% for MEaSUREs in the cold plateau mountain climate and plateau continental climate area (Saihanba and Chengduo) with frozen ground distributed seasonally, respectively. The overall accuracy is 69.05% for SMAP, 76.5% for AMSR2 and 81.4% for MEaSUREs in the Ngari, Naqu, and Dachaidan regions belonging to arid and semi-arid climates. It can be seen that SMAP and AMSR2 achieve the best performance in the distributed permafrost area, the second-best performance in the seasonal distributed permafrost area, but the worst performance in the areas with arid and semi-arid climate types due to inconsistent F/T signals between water with small changes and temperature with apparent changes during the F/T transition. The MEaSUREs product showed almost the same performance in different regions, indicating that it was less affected by climate types and the distribution of frozen soil than SMAP and AMSR2 products. SMAP F/T product detected by L-band with long penetration and AMSR2 F/T product calibrated with 5 cm soil temperature could represent the 5 cm F/T, but the MEaSUREs F/T product was more likely to describe the surface F/T state due to calibrated with air temperature and the short penetration of 36.5 GHz. In mid-low latitude areas (Tianjun and Qumalai) with a short duration of snow cover days and a fast snowmelt, the effect of snow melting on F/T products was negligible. Moreover, the spring snowmelt affects the three F/T products in Chengduo, but the SMAP product is not affected by the winter snowmelt, whereas the AMSR2 product is affected by the winter snowmelt.

Development of a Shallow-Depth Soil Temperature Estimation Model Based on Air Temperatures and Soil Water Contents in a Permafrost Area

A model for predicting shallow depth soil temperatures is important and effective to assess the changes in soil conditions related to global climate change and local disturbances. Shallow-depth soil temperature estimation model in cold region in Alaska is developed based on thermal response using air temperature and shallow-depth soil water content during active layer development period of 160 days from May to October. Among the seven soil temperature measurement sites, data from four sites were used for model development, and the remaining three sites were used for model validation. Near the middle of the seven measurement sites, air temperature is monitored at one location. The proposed model implemented concepts of thermal response and cumulative temperature. Temperatures and soil water contents were measured using automated remote sensing technology. Consequently, it was confirmed that the developed model enables fast and accurate assessment of shallow-depth soil temperature during active soil layer development period.

Analysis of soil depth temperature changes in Iran according to classification of atmospheric circulation patterns

The purpose of this study was to investigate the relationship between atmospheric circulation patterns and soil depth temperature changes in Iran. To verify the correlation between atmospheric circulation patterns and soil temperature changes in the country, ten synoptic stations in the geographical range of Iran representing different climates were selected for research and analysis of data. To extract the circulation patterns by cluster analysis using Ward linkage method, nine circular clusters were identified and extracted. Among the patterns, five patterns were identified during the cold season, two patterns during the warm period, and two patterns during the transition period. Soil temperature data were first deseasonalized and changes (increase and decrease) due to the presence of warm and cold season were removed. The results of the correlation analysis between soil temperature changes in the nine-dimensional or nonuple patterns showed that there was no significant correlation between the mentioned patterns and temperature changes in the studied stations in models No. 1 and No. 2. The results of correlation analysis also showed that there was significant correlation between circulation patterns and soil temperature changes in seven other circulation patterns. The results of correlation analysis also showed that among patterns of circulation, patterns 7, 4, and 9 had the most impact on soil temperature changes in the country.

Interactive effects of hydrological conditions on soil respiration in China's Horqin sandy land: An example of dune-meadow cascade ecosystem

Soil moisture (Ms) strongly influences dynamic changes in soil respiration (Rs) and is thus an important factor when predicting soil carbon emissions. However, the various sources of Ms (rainfall, groundwater, and condensation) exert complicated and uncertain effects on Rs. This study examined the growth seasonal variation (from April to October) of Rs and the diurnal variation in a cascade ecosystem consisting of sandy bare ground, a transitional artificial Populus forest, and a meadow Phragmites communis community in China's Horqin sandy land. Simultaneous measurements of the 0–10 cm depth soil temperature (Ts) and Ms, rainfall, the surface air relative humidity and the groundwater depth were collected. The results revealed that in sandy bare ground with Ms below field capacity, Ms had a greater impact on Rs than Ts, and rainfall could increase Rs. The effect of condensation on Rs during periods of continuous drought could not be ignored. In the meadowlands with Ms above field capacity, the groundwater affected Rs indirectly by regulating Ms and the relationship with Ts, and rainfall had an adverse effect on Rs. The effects of rainfall, Ms and Ts on Rs were minimum as Ms approached the saturation water content. In the transitional forest, Ms and Ts were the main factors controlling Rs. The most favorable Ms for Rs was close to the field capacity. The results emphasize that field capacity and saturation water content are the demarcation points of a soil carbon emissions prediction model, and the effect of different hydrological conditions and Ts on Rs at each segment are reconsidered accordingly. Ultimately, the carbon emission patterns of the cascade ecosystems in arid and semi-arid areas are extremely complicated and have to be considered specially for estimating terrestrial carbon emissions.

Infrared heater system for warming tropical forest understory plants and soils.

The response of tropical forests to global warming is one of the largest uncertainties in predicting the future carbon balance of Earth. To determine the likely effects of elevated temperatures on tropical forest understory plants and soils, as well as other ecosystems, an infrared (IR) heater system was developed to provide in situ warming for the Tropical Responses to Altered Climate Experiment (TRACE) in the Luquillo Experimental Forest in Puerto Rico. Three replicate heated 4‐m‐diameter plots were warmed to maintain a 4°C increase in understory vegetation compared to three unheated control plots, as sensed by IR thermometers. The equipment was larger than any used previously and was subjected to challenges different from those of many temperate ecosystem warming systems, including frequent power surges and outages, high humidity, heavy rains, hurricanes, saturated clayey soils, and steep slopes. The system was able to maintain the target 4.0°C increase in hourly average vegetation temperatures to within ± 0.1°C. The vegetation was heterogeneous and on a 21° slope, which decreased uniformity of the warming treatment on the plots; yet, the green leaves were fairly uniformly warmed, and there was little difference among 0–10 cm depth soil temperatures at the plot centers, edges, and midway between. Soil temperatures at the 40–50 cm depth increased about 3°C compared to the controls after a month of warming. As expected, the soil in the heated plots dried faster than that of the control plots, but the average soil moisture remained adequate for the plants. The TRACE heating system produced an adequately uniform warming precisely controlled down to at least 50‐cm soil depth, thereby creating a treatment that allows for assessing mechanistic responses of tropical plants and soil to warming, with applicability to other ecosystems. No physical obstacles to scaling the approach to taller vegetation (i.e., trees) and larger plots were observed.

Temporal Dynamics of Phlebotomine Sand Flies Population in Response to Ambient Temperature Variation, Bam, Kerman Province of Iran

BackgroundVariations in climate condition may have changed the dynamic of zoonotic cutaneous leishmaniasis (ZCL) and its agents such as sand flies and reservoir in the Bam Kerman the dry region of Iran. ObjectivesIn this study we intend to examine the seasonal and interannual dynamics of the phlebotomine mosquito as a function of ambient temperature in Bam, Kerman one of the main leshmaniasis prevalence area in Iran. MethodsThe MODIS land surface temperature product (LST; MODIS/Terra LST/E Monthly L3 Global 0.05Deg CMG [MOD11C3]) and land-based climatic data were used as explanatory variables. Monthly caught mosquitoes in Bam, Kerman, were used as a dependent variable. The temporal associations were first investigated by inspection of scatterplots and single-variable regression analysis. A multivariate linear regression model was developed to reveal the association between ambient temperature and the monthly mosquito abundance at a 95% confidence level (P < 0.05). FindingsThe findings indicated that the monthly variation of 0-10 cm of soil depth temperature is the main driver of phlebotomine mosquito temporal dynamics. The developed multivariate model also indicated that the ambient temperature variation was responsible for >0.80 of temporal dynamics of phlebotomine mosquitos in Bam.

Environmental Factors and Soil CO2Emissions in an Alpine Swamp Meadow Ecosystem on the Tibetan Plateau in Response to Experimental Warming

We examined the response of soil CO2emissions to warming and environmental control mechanisms in an alpine swamp meadow ecosystem on the Tibetan Plateau. Experimental warming treatments were performed in an alpine swamp meadow ecosystem using two open-top chambers (OTCs) 40 cm (OA) and 80 cm (OB) tall. The results indicate that temperatures were increased by 2.79°C in OA and 4.96°C in OB, that ecosystem CO2efflux showed remarkable seasonal variations in the control (CK) and the two warming treatments, and that all three systems yielded peak values in August of 123.6, 142.3, and 166.2 g C m−2 month−1. Annual CO2efflux also showed a gradual upward trend with increased warming: OB (684.1 g C m−2 year−1) &gt; OA (580.7 g C m−2 year−1) &gt; CK (473.3 g C m−2 year−1). Path analysis revealed that the 5 cm depth soil temperature was the most important environmental factor affecting soil CO2emissions in the three systems.

The estimation of daily mean soil temperature at different depths in three Agroecological regions of Sri Lanka

Soil temperature is an important climatic variable in regulating ecosystem process, yet it is difficult and costly to measure daily. Several mathematical models are available to estimate soil temperature; however, most are with complicated independent variables. In this research, site specific parsimonious models were developed to estimate daily mean soil temperature in deeper depths (i.e.&gt;10 cm) using air temperature, soil temperature at 5 cm depth and day of the year as independent variables. Different models were developed for four Coconut growing sites and results showed that 5 cm depth soil temperature along with day of the year estimate the soil temperature at deeper depths with high accuracy. Further, models with air temperature and day of the year estimate the soil temperature at 5 and 10 cm depths satisfactorily. These models can be used to estimate the daily mean soil temperature simply and cost effectively and it also allows the reconstruction of missing soil temperature values. COCOS Vol. 20: 9-25 (2013)

Soil temperature and soil water potential under thin oxodegradable plastic film impact on cotton crop establishment and yield

Field experiments were undertaken to determine the effect of oxodegradable thin film on cotton establishment and lint yield. It was hypothesised that the use of thin oxodegradable plastic film would increase soil temperature and conserve seedbed water possibly reducing the risk in early planting, while not reducing lint yield or fibre quality of cotton. Experiments were conducted near Narrabri, NSW Australia during the 2010, 2012–2014 and the 2012 and 2013 seasons near Griffith, a cooler region in southern NSW with three or four thin oxodegradable plastic films with different formulations and break down rates being compared with a bare soil treatment. Planting depth soil temperature and soil water potential was monitored at three hourly intervals. Soil temperatures were elevated by 2–4°C under the film compared with the bare soil that resulted in earlier (2–4 days) emergence of cotton under the film compared with bare soil. Soil also remained wetter beneath the film. Two films began to degrade at the time when cotton seedlings emerged (10–20 days), resulting in greater seedling survival (2–7 vs 12plants/m). Seedlings were unable to penetrate four films on emergence and did not survive. When these films were slit to allow seedling growth, survival depended on subsequent environmental conditions; whether overcast/sunny or cool/warm conditions occurred. Using film that had been slotted prior to being laid in the field also increased soil temperature and conserved seedbed water. This enhanced (50–80%) emergence and survival of emerged seedlings, and overcame the need to slit film in the field.A climate analysis and simulation study was also conducted to determine the benefit or otherwise of thin film and early planting over a longer-term than is possible from field studies. Results for both sites indicated that the earlier the planting date (August/September), compared to a “normal” planting date (October) there was a greater the chance of cold (6.5 vs 2.5 days) and frost (2.5 vs 0 days) being experienced, which resulted in lower or no lint yield. Lint yield tended to be greater (3200 vs 2800kglint/ha), although not significantly so, with thin film compared with bare soil. Fibre quality parameters were not affected by the use of thin film. All surface film had degraded by the end of the season posing no risk of contamination of the lint. Film below ground did remained intact, but this does not pose a contamination risk for the cotton lint at harvest. No plastic film was detected in ginned cotton after being machine harvested at both sites.There was no significant benefit in lint yield due to thin film, while all fibre quality parameters made base grade. Long-term simulation of early planting, with and without thin film, indicated that lint yield was variable with no consistent benefit due to the presence of thin film for the locations simulated. There is still a risk of cold weather or frost occurring when planting early with thin film that growers need to consider. In practical terms it is anticipated that growers would potentially only plant 5% of their area early depending on the seasonal forecast.

Prediction of soil frost penetration depth in northwest of Iran using air freezing indices

Information about soil frost penetration depth can be effective in finding appropriate solutions to reduce the agricultural crop damage, transportations, and building facilities. Amongst proper methods to achieve this information are the statistical and empirical models capable of estimating soil frost penetration depth. Therefore, the main objective of this research is to calculate soil frost penetration depth in northwest of Iran during the year 2007–2008 to validate two different models accuracy. To do so, the relationship between air and soil temperature in different depths (5-10-20-30-50-100 cm) at three times of the day (3, 9, and 15 GMT) for 14 weather stations over 7 provinces was analyzed using linear regression. Then, two different air freezing indices (AFIs) including Norwegian and Finn AFI was implemented. Finally, the frost penetration depth was calculated by McKeown method and the accuracy of models determined by actual soil frost penetration depth. The results demonstrated that there is a significant correlation between air and soil depth temperature in all studied stations up to the 30 cm under the surface. Also, according to the results, Norwegian index can be effectively used for determination of soil frost depth penetration and the correlation coefficient between actual and estimated soil frost penetration depth is r = 0.92 while the Finn index overestimates the frost depth in all stations with correlation coefficient r = 0.70.

English

The effects of olive mill effluent on evaporation assessed from the surface of two kinds of soil sandy loam and loam textures with two different temperatures. In the other hand five treatments for each texture were prepared in three replicates, including wastewater treatment stained with olives in a value and two percent, compost mixture treatments, mulch amount equal to 50 tons/h, control and water. Eleven treatments were used. Treatments only to a depth of 5.0 cm of soil were applied. 0.0 to 5.0 cm depth of soil particles passed through the eight millimeters sieve and the remaining depth to bottom pot (13 cm) were full by a particle passed through 2.0 mm sieve. By measuring weight loss pots completely wet every day of the evaporating three months for each period temperature were assessed. Soil temperature in depths of 2.0 and 10.0 cm twice each day, once at 8 a.m. (temperature achieved during the night) and the other at 19 p.m. (temperature gained during the day) were recorded. Stored soil moisture in different potential (zero, 0.05, 0.1, 0.3, 1.5 and 15 bar) in the olive mill effluent for both texture by pressure plates and tempi cells were measured. Statistical analysis of data from completely randomized design (CRD). These results indicate that the rate of the hydrophobic material used in both textures had indirect relation with evaporation from the soil surface. Key words: Olive mill effluent, mulch, compost mixture, evaporation.

Impact of protective shelterbelt microclimate characteristics

Abstract Evaluation of microclimate characteristics of a protective shelterbelt in Obelisk enclosure in 2010. Vegetation performs indispensable functions in the landscape. Protective shelterbelts are important landscape elements. Individual interventions to these ecosystems should be made with the intention to increase the retention capacity of the landscape, the biodiversity, and the stability of individual landscape elements and the landscape as a whole. This article presents the results of the measuring of the effect of model forest vegetation in the proximity of Obelisk in the Lednice-Valtice area on the microclimate. The protective shelterbelt, declared as a forest stand, is located in the cadastral area of Lednice, Podivin and Rakvice. A set of weather stations, supplied by AMET- Litschmann and Suchy Velke Bilovice, was used for the measuring. The stations measured wind velocity (m/s), soil temperature in depths of 5 and 10 cm (°C), air temperature (°C), radiation (W.m-2) and precipitation (mm) from January 1 to December 31, 2010. The ImageTool application was used to establish optical porosity, based on photos taken in summer and winter. Optical porosity was established as a ratio of white spots to their total number in a specific section of a photograph. The optical porosity was 5% during the growing season and 23% outside the growing season. These values significantly differ from the optimum values for efficient semi-permeable PS, whose porosity is set to 40-50%.

Modeling Soil Heat Flux in R

Knowing of soil heat flow properties of a crop field inform the farmer about temperature conditions of seeds germination. Soil heat flow today is either measured or modeled. In our study we rely on the procedure developed by Sang-Ok Chung and Robert Horton (1987). Applicability of the R language version heat flux model we studied on data collected by Gábor Szász director of the Agro-meteorological Observatory of Debrecen, Kismacs in May 2001.). Soil temperature data were collected in 5, 25 and 50 cm depth in 15 minute intervals from a loam texture chernozem soil covered with short grass. The used upper boundary layer at 5 cm and the lower boundary at 50 cm soil temperature data contain 2976 time periods. Temperature values measured at 5 and 50 cm depths were used as upper and lower boundary conditions, respectively. Using the R programmed heat flux model the 25 cm depth soil temperature was simulated and compared to the measured ones. Since the simulated and measured soil temperatures differed significantly we assumed necessity of coupling heat and moisture flux for describing time change of soil temperate. Our final conclusion is that because of the strong correlation between water flow and soil temperature, it is essential to make simultaneous estimations of them both when modeling soil temperature.

Estimation of bare soil surface temperature from air temperature and soil depth temperature in a tropical station.

Soil surface temperature has critical influence on climate, agricultural and hydrological activities since it serves as a good indicator of the energy budget of the earth’s surface. Two empirical models for estimating soil surface temperature from air temperature and soil depth temperature were developed. The coefficient of determination (R2) of soil surface temperature from the air temperature model ranged from 0.92 - 0.99, while the mean absolute error (MAE) and root mean squared error (RMSE) ranged from 0.5 - 2.48 and 0.77 - 2.630C respectively. For the soil depth model, the R2 value ranged from 0.75 - 0.96, MAE ranged between 1.05 and 4.94, while RMSE ranged from 1.28 - 5.25. Both models performed well on days of year (DOYs), under similar prevailing weather conditions during the model training period. Keyword : Air, Soil, temperature, prevailing weather, energy budget, earth surface