Field Validation of DNDC and SWAP Models for Temperature and Water Content of Loamy and Sandy Loam Spodosols

2014 ◽  
Vol 28 (2) ◽  
pp. 133-142 ◽  
Author(s):  
Eugene Balashov ◽  
Natalya Buchkina ◽  
Elena Rizhiya ◽  
Csilla Farkas
Keyword(s):  
Sensitivity Analysis ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Root Mean Square ◽  
Seasonal Dynamics ◽  
Mean Square ◽  
Plant Model ◽  
Decomposition Model ◽  
Soil Temperatures

Abstract The objectives of the research were to: fulfil the preliminary assessment of the sensitivity of the soil, water, atmosphere, and plant and denitrification and decomposition models to variations of climate variables based on the existing soil database; validate the soil, water, atmosphere, and plant and denitrification and decomposition modelled outcomes against measured records for soil temperature and water content. The statistical analyses were conducted by the sensitivity analysis, Nash-Sutcliffe efficiency coefficients and root mean square error using measured and modelled variables during three growing seasons. Results of sensitivity analysis demonstrated that: soil temperatures predicted by the soil, water, atmosphere, and plant model showed a more reliable sensitivity to the variations of input air temperatures; soil water content predicted by the denitrification and decomposition model had a better reliability in the sensitivity to daily precipitation changes. The root mean square errors and Nash-Sutcliffe efficiency coefficients demonstrated that: the soil, water, atmosphere, and plant model had a better efficiency in predicting seasonal dynamics of soil temperatures than the denitrification and decomposition model; and among two studied models, the denitrification and decomposition model showed a better capability in predicting the seasonal dynamics of soil water content.

The effects of CO2 database on a localized AquaCrop model construction based on the field experiment

2021 ◽  
Author(s):  
fawen li ◽  
chunya song ◽  
hua li
Keyword(s):  
Root Mean Square Error ◽  
Winter Wheat ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Mean Square Error ◽  
North China Plain ◽  
North China ◽  
Mean Square ◽  
Simulation Results

Abstract To examine whether the use of default CO2 database affected the simulation results, this paper built the AquaCrop models of winter wheat based on the measured CO2 database and the default CO2 database, respectively. The models were calibrated with data (2017–2018) and validated with the data (2018–2019) in the North China Plain. The residual coefficient method (CRM), root mean square error (RMSE), normalized root mean square error (NRMSE) and determination coefficient (R2) were used to test the model performance. The results showed that the accuracy of simulation under the two CO2 database were both good. Compared with the default CO2 database, the simulation accuracy under the measured CO2 database had higher accuracy. In order to verify the model further, the simulated values of evapotranspiration, soil water content and measured values were compared and analyzed. The results showed that there were some errors between the measured evapotranspiration and the values of simulation in the filling and waxing period of winter wheat. In general, the simulation values of evapotranspiration were consistent with the measured value at different irrigation levels. The simulated values ​​of the soil water content at the three levels of irrigation were all higher than the measured values, but the simulated results basically reflected the dynamic changes of soil water content throughout the growth period. The model adjustment value of WP*(the normalized water productivity) were a difference under the two CO2 databases, which is one of the reasons for the difference in the simulation results. The results show that in the absence of measured CO2 data, the default CO2 database can be used, which has little influence on the model construction, and the accuracy of the model constructed meets the actual demand. The research results can provide a basis for the establishment of crop models in North China Plain.

The Effects of Temperature and Humidity on a Field Population of Bradysia odoriphaga (Diptera: Sciaridae)

2020 ◽  
Vol 113 (4) ◽  
pp. 1927-1932
Author(s):  
Cai-hua Shi ◽  
Jing-rong Hu ◽  
You-jun Zhang
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Control Strategies ◽  
Beijing City ◽  
Drought Treatment ◽  
High Soil ◽  
Soil Temperatures ◽  
Water Contents ◽  
Soil Water Contents

Abstract The production of Chinese chives is reduced throughout China due to a root-feeding dipteran pest Bradysia odoriphaga Yang et Zhang (Diptera: Sciaridae), therefore deciphering the conditions influencing its growth and development are important in developing ecological control strategies. A study was conducted from 2014 to 2017 to determine the relationship between the abundance of B. odoriphaga and temperature (atmospheric and soil), soil water content, and atmospheric humidity in a Chinese chive field in Beijing City, China. Numbers of adults peaked in March and October to November and were lowest in July to August and December to next February; numbers of larvae were highest in December to next February and lowest in July to August. From 2014 to 2017, the numbers of adults and larvae were significantly correlated with monthly mean atmospheric temperatures and soil temperatures, but were not significantly correlated with monthly mean atmospheric relative humidity and soil water content. However, for both adults and larvae, numbers were significantly greater with high soil water contents compared with drought treatment. The results of this study suggest that the very low soil water contents, high atmospheric temperatures, and high soil temperatures were critical for regulating field populations of B. odoriphaga.

scholarly journals How do Soil Moisture and Vegetation Covers Influence Soil Temperature in Drylands of Mediterranean Regions?

Water ◽  
2018 ◽  
Vol 10 (12) ◽  
pp. 1747 ◽  
Author(s):  
Javier Lozano-Parra ◽  
Manuel Pulido ◽  
Carlos Lozano-Fondón ◽  
Susanne Schnabel
Keyword(s):  
Soil Moisture ◽  
Soil Temperature ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Vegetation Cover ◽  
Daily Maximum ◽  
Local Climate ◽  
Tree Canopies ◽  
Soil Temperatures

Interactions between land and atmosphere directly influence hydrometeorological processes and, therefore, the local climate. However, because of heterogeneity of vegetation covers these feedbacks can change over small areas, becoming more complex. This study aims to define how the interactions between soil moisture and vegetation covers influence soil temperatures in very water-limited environments. In order to do that, soil water content and soil temperature were continuously monitored with a frequency of 30 min over two and half hydrological years, using capacitance and temperature sensors that were located in open grasslands and below tree canopies. The study was carried out on three study areas located in drylands of Mediterranean climate. Results highlighted the importance of soil moisture and vegetation cover in modifying soil temperatures. During daytime and with low soil moisture conditions, daily maximum soil temperatures were, on average, 7.1 °C lower below tree canopies than in the air, whereas they were 4.2 °C higher in grasslands than in the air. As soil wetness decreased, soil temperature increased, although this effect was significantly weaker below tree canopies than in grasslands. Both high soil water content and the effect of shading were reflected in a decrease of maximum soil temperatures and of their daily amplitudes. Statistical analysis emphasized the influence of soil temperature on soil water reduction, regardless of vegetation cover. If soil moisture deficits become more frequent due to climate change, variations in soil temperature could increase, affecting hydrometeorological processes and local climate.

scholarly journals Process-based modelling of NH<sub>3</sub> exchange with grazed grasslands

2017 ◽  
Vol 14 (18) ◽  
pp. 4161-4193 ◽  
Author(s):  
Andrea Móring ◽  
Massimo Vieno ◽  
Ruth M. Doherty ◽  
Celia Milford ◽  
Eiko Nemitz ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Soil Ph ◽  
Regional Scale ◽  
Scale Model ◽  
Nh3 Emission ◽  
Initial Soil ◽  
The Difference

Abstract. In this study the GAG model, a process-based ammonia (NH3) emission model for urine patches, was extended and applied for the field scale. The new model (GAG_field) was tested over two modelling periods, for which micrometeorological NH3 flux data were available. Acknowledging uncertainties in the measurements, the model was able to simulate the main features of the observed fluxes. The temporal evolution of the simulated NH3 exchange flux was found to be dominated by NH3 emission from the urine patches, offset by simultaneous NH3 deposition to areas of the field not affected by urine. The simulations show how NH3 fluxes over a grazed field in a given day can be affected by urine patches deposited several days earlier, linked to the interaction of volatilization processes with soil pH dynamics. Sensitivity analysis showed that GAG_field was more sensitive to soil buffering capacity (β), field capacity (θfc) and permanent wilting point (θpwp) than the patch-scale model. The reason for these different sensitivities is dual. Firstly, the difference originates from the different scales. Secondly, the difference can be explained by the different initial soil pH and physical properties, which determine the maximum volume of urine that can be stored in the NH3 source layer. It was found that in the case of urine patches with a higher initial soil pH and higher initial soil water content, the sensitivity of NH3 exchange to β was stronger. Also, in the case of a higher initial soil water content, NH3 exchange was more sensitive to the changes in θfc and θpwp. The sensitivity analysis showed that the nitrogen content of urine (cN) is associated with high uncertainty in the simulated fluxes. However, model experiments based on cN values randomized from an estimated statistical distribution indicated that this uncertainty is considerably smaller in practice. Finally, GAG_field was tested with a constant soil pH of 7.5. The variation of NH3 fluxes simulated in this way showed a good agreement with those from the simulations with the original approach, accounting for a dynamically changing soil pH. These results suggest a way for model simplification when GAG_field is applied later at regional scale.

scholarly journals Comments on “Estimating Soil Water Contents from Soil Temperature Measurements by Using an Adaptive Kalman Filter”

2005 ◽  
Vol 44 (4) ◽  
pp. 546-550 ◽  
Author(s):  
Kun Yang ◽  
Toshio Koike
Keyword(s):  
Kalman Filter ◽  
Soil Temperature ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Thermal Parameter ◽  
Monotonic Function ◽  
Temperature Measurements ◽  
Adaptive Kalman Filter ◽  
Soil Temperatures

Abstract A scheme was proposed by Zhang et al. to estimate soil water content from soil temperature measurements by using an adaptive Kalman filter. Their scheme is based on the fact that soil heat capacity and thermal conductivity are a monotonic function of soil water content. However, thermal diffusivity, a more critical thermal parameter in such an estimation, is not a monotonic function of soil water content in most cases. This could result in multiple solutions in some cases when deriving soil water content from soil temperatures.

Comparison between Soil Water Dynamics Simulated by the Isothermal and Non-Isothermal Models

2013 ◽  
Vol 864-867 ◽  
pp. 2298-2301
Author(s):  
Jiang Bo Han ◽  
Zhi Fang Zhou
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Water Table ◽  
Water Dynamics ◽  
Soil Water Dynamics ◽  
Isothermal Model ◽  
Dynamic Variations ◽  
Soil Temperatures ◽  
One Year

To obtain a better understanding of the role of non-isothermal flow in the unsaturated zone in the presence of the water table, the isothermal and non-isothermal models driven by the observed atmospheric data were used to reproduce soil moisture dynamics observed in the lysimeter with a 100-cm water table level over one year period. Results from the simulations indicated that although the isothermal and non-isothermal models both captured the general trend of soil water content dynamics during one year period, simulated values by the isothermal model presented less dynamic variations, which overestimated the soil water content during the rainy season and underestimated it during other periods. On the other hand, the non-isothermal model not only reproduced well the seasonal variations of soil temperatures but also reproduced more reasonably soil water dynamics in the whole profile and during the whole simulation period.

scholarly journals Soil contribution to CO2 fluxes in Chinampa ecosystems, Mexico

2020 ◽  
Vol 10 ◽  
Author(s):  
Elena Nikolaevna Ikkonen ◽  
Norma Eugenia García-Calderón ◽  
Ervin Stephan-Otto ◽  
Elizabeth Fuentes-Romero ◽  
Abel Ibáñez-Huerta ◽  
...  
Keyword(s):  
Seasonal Variation ◽  
Plant Growth ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Seasonal Dynamics ◽  
Plant Biomass ◽  
Vegetation Type ◽  
Ecosystem Carbon ◽  
Dominant Plant Species

Since soil CO<sub>2</sub> flux is a key component of ecosystem carbon balance, quantifying its contribution to the ecosystem carbon flux and understanding the factors that underlie its temporal variation is crucial for a better comprehension of ecosystem carbon dynamics under climate change and for optimal ecosystem use and management. Our objectives were to quantify the contributions of total soil CO<sub>2</sub> efflux (<em>F</em><sub>S</sub>) to ecosystem respiration (<em>R</em><sub>E</sub>) and heterotrophic soil CO<sub>2</sub> efflux (<em>F</em><sub>H</sub>) to <em>F</em><sub>S</sub> in two <em>chinampa</em> ecosystems with different natural grass covers. We also aimed to identify the main environmental drivers of seasonal variability of these contributions. The CO<sub>2</sub> fluxes were measured on each site about every 14 days from September 2008 to August 2009 in the Xochimilco Ecological Park in Mexico City using dark chamber techniques. For two studied sites, <em>R</em><sub>E</sub>,<em> F</em><sub>S</sub> and <em>F</em><sub>H</sub> were estimated on average as 94.1 ± 8.5, 34.7 ± 3.5 and 16.5 ± 1.7 (± S.E.) mg C-CO<sub>2</sub> m<sup>-2</sup> h<sup>-1</sup>, respectively. &nbsp;On average over the study period and sites, the annual cumulative <em>R</em><sub>E</sub>, <em>F</em><sub>S</sub> and <em>F</em><sub>H</sub> fluxes were 824 ± 74, 304 ± 31 and 145 ± 15 g C m<sup>-2</sup> year, respectively. The <em>R</em><sub>E</sub>, <em>F</em><sub>S</sub> and <em>F</em><sub>H</sub> varied between the winter and summer seasons; this variation was explained mostly by seasonal variations of soil temperature, soil water content and shoot plant biomass. Temperature sensitivity of CO<sub>2</sub> fluxes depended on vegetation type and plant growth differences among the sites and decreased in the following order: <em>R</em><sub>E</sub> &gt; <em>R</em><sub>s</sub> &gt; <em>R</em><sub>H</sub>. The contribution of <em>F</em><sub>S</sub> to <em>R</em><sub>E</sub> and <em>F</em><sub>H</sub> to <em>F</em><sub>S</sub> for the two studied sites and period averaged about 38% and 50%, respectively regardless of the site vegetation type, but the degree of <em>F</em><sub>S</sub>/<em>R</em><sub>E</sub> and <em>F</em><sub>H</sub>/<em>F</em><sub>S</sub> variability depended on the differences in seasonal dynamics of plant cover. The contribution of <em>F</em><sub>H </sub>to <em>F</em><sub>S</sub> varied from 37% in summer to 73% in winter at the site without a seasonal shift in dominant plant species, but <em>F</em><sub>H</sub>/<em>F</em><sub>S</sub> was close to constant during the year at the site with a seasonal change in dominant plant species. During the cold period, the contribution of <em>F</em><sub>H </sub>to <em>F</em><sub>S</sub> increased following plant growth decrease. The linear regression analysis showed that plant biomass was the dominant factor controlling the seasonal variation of <em>F</em><sub>H</sub>/<em>F</em><sub>S</sub> ratios, whereas the plant biomass dynamic followed the dynamics of soil water content, water table depth, and soil temperature. Our results suggest that seasonal variation of soil contribution to total fluxes from the <em>chinampa</em> ecosystem is locally differentiated. These differences were related to differences in seasonal dynamics of cover productivity which has been associated with localization of soil water content. This finding has important implications for assessing the contribution of the chinampa ecosystem to the global carbon budget.

Selection and use of representative sites in a large neutron moisture meter network

Soil Research ◽  
1979 ◽  
Vol 17 (2) ◽  
pp. 249 ◽  
Author(s):  
GG Johns
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Root Mean Square ◽  
Mean Square ◽  
Short Term ◽  
Moisture Meter ◽  
Routine Basis ◽  
Neutron Moisture ◽  
Key Sites ◽  
The Relationship

The assessment of the representivity of individual sites in a large neutron moisture meter (NMM) network, and the errors incurred by selecting subsets of various sizes, and using different methods to estimate the full set value from the subsets, is described. Soil water data collected over 13 months from the NMM network (240 sites, divided into eight strata) were analysed to determine the relationship between individual sites and their stratum means. Relationships were assessed using the following four methods: (1) root mean square of the discrepancy; (2) linear regression; (3) quadratic regression; (4) power curve regression. Sites best related to their stratum means were then included in various size subsets, and estimates based on these subsets were compared with the respective full stratum means using 24 months' data. The best estimates of stratum means were obtained by using quadratic regressions and c. eight sites per subset. Using this method, the root mean square discrepancy between estimates of profile water content and observed full stratum means averaged 2.1 mm when the total profile was estimated directly and 2.5 mm when the profile water content was computed as the sum of individual estimates for four arbitrary horizons within the profile. Daily readings of one group of selected subsets indicated the potential of frequent NMM readings at key sites to indicate short-term changes in the soil water content of an area. The performance of the selected subsets has been monitored for a further 12 months as an independent check on their representivity. The root mean square discrepancy of estimates during that period was 2.7 mm. Subsequently only the selected eight sites in each stratum of the field study are being read on a routine basis.

Seasonal dynamics of soil water content in the typical vegetation and its response to precipitation in a semi-arid area of Chinese Loess Plateau

2021 ◽  
Vol 13 (10) ◽  
pp. 1015-1025
Author(s):  
Tairan Zhou ◽  
Chun Han ◽  
Linjie Qiao ◽  
Chaojie Ren ◽  
Tao Wen ◽  
...  
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Loess Plateau ◽  
Seasonal Dynamics ◽  
Arid Area ◽  
Chinese Loess Plateau ◽  
Chinese Loess ◽  
Semi Arid

Studies on the behavior and survival of Phytophthora cactorum in soil

1974 ◽  
Vol 52 (4) ◽  
pp. 795-802 ◽  
Author(s):  
B. Sneh ◽  
D. L. McIntosh
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Germ Tube ◽  
Phytophthora Cactorum ◽  
Moist Soil ◽  
Soil Temperatures ◽  
Water Contents ◽  
Soil Water Contents ◽  
Germ Tube Elongation

Sporangia and oospores of P. cactorum persisted for appreciable periods in soil at temperatures and soil water contents likely to prevail during a growing season.Mycelium lysed more rapidly as soil water content and temperature increased. Hyphae were not viable after 3 days incubation in wet soil at 29 °C but survived for at least 45 days at 4 °C.At soil water contents higher than 3.0 bars suction and at soil temperatures above 10 °C sporangia appeared on mycelium buried in soil. When soil moisture was reduced to 3.0 bars suction and temperature to 10 °C, oogonia were formed.Longevity of sporangia was reduced by increasing soil water content above 0.3 bars suction. Glucose added to soil induced germination of sporangia and germ tube elongation, while asparagine inhibited germination.Sporangia and oospores but not mycelium survived freezing temperatures in moist soil. Sporangia could not be recovered from soil which had been allowed to dry. Some oospores germinated after drying.

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