scholarly journals Plant biomass, soil water content and soil N:P ratio regulating soil microbial functional diversity in a temperate steppe: A regional scale study

2010 ◽  
Vol 42 (3) ◽  
pp. 445-450 ◽  
Author(s):  
Zhanfeng Liu ◽  
Bojie Fu ◽  
Xiaoxuan Zheng ◽  
Guohua Liu
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Functional Diversity ◽  
Plant Biomass ◽  
Regional Scale ◽  
N:P Ratio ◽  
Temperate Steppe ◽  
Microbial Functional Diversity ◽  
Soil Microbial

Evaluating Soil Water Content in a WRF-Noah Downscaling Experiment

2013 ◽  
Vol 52 (10) ◽  
pp. 2312-2327 ◽  
Author(s):  
Peter Greve ◽  
Kirsten Warrach-Sagi ◽  
Volker Wulfmeyer
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Land Surface ◽  
Root Zone ◽  
Regional Scale ◽  
Land Surface Model ◽  
Surface Model ◽  
Flux Partitioning

AbstractSoil water content (SWC) depends on and affects the energy flux partitioning at the land–atmosphere interface. Above all, the latent heat flux is limited by the SWC of the root zone on one hand and radiation on the other. Therefore, SWC is a key variable in the climate system. In this study, the performance of the Weather Research and Forecasting model coupled with the Noah land surface model (WRF-Noah) system in a climate hindcast simulation from 1990 to 2008 is evaluated with respect to SWC versus two reanalysis datasets for Europe during 2007 and 2008 with in situ soil moisture observations from southern France. When compared with the in situ observations, WRF-Noah generally reproduces the SWC annual cycle while the reanalysis SWCs do not. The biases in areal mean WRF-Noah SWCs relate to biases in precipitation and evapotranspiration in a cropland environment. The spatial patterns and temporal variability of the seasonal mean SWCs from the WRF-Noah simulations and from the two reanalyses correspond well, while absolute values differ significantly, especially at the regional scale.

scholarly journals Glasshouse study of a sprayable, degradable polymer to reduce water use in cotton establishment

Soil Research ◽  
2020 ◽  
Vol 58 (4) ◽  
pp. 379
Author(s):  
Priscilla Johnston ◽  
Michael Braunack ◽  
Philip S. Casey ◽  
Keith L. Bristow ◽  
Raju Adhikari
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Plant Biomass ◽  
Sandy Loam ◽  
Seedling Emergence ◽  
Chemical Properties ◽  
Water Evaporation ◽  
Degradable Polymer ◽  
Extensive Degradation

This glasshouse pot experiment demonstrated that a new sprayable and degradable polymer reduced soil water evaporation and promoted cotton seedling emergence and establishment. The polymer was tested on two contrasting soils (sandy loam and clay), representative of those used to grow cotton in Australia. Changes in soil water content in non-treated and polymer-treated pots were monitored over 80 days, after surface or subsurface watering. Plant biomass, soil water content and soil chemical properties were determined at harvest. The polymer reduced soil water evaporation by up to 35% in sandy loam and up to 20% in clay, did not compromise seedling emergence and improved plant growth per unit water applied by up to 26.2%. The polymer underwent extensive degradation after 80 days to produce low molecular-weight polymers or oligomers and water-extractable silicon species that may have implications for plant nutrition.

Modeling effects of plastic mulching on crop yields and water productivity in the middle Heihe River Basin

2020 ◽  
Author(s):  
Wang Zhang ◽  
Chunmiao Zheng
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Global Sensitivity Analysis ◽  
Water Productivity ◽  
Regional Scale ◽  
Canopy Cover ◽  
Heihe River ◽  
Aquacrop Model ◽  
Plastic Mulching

<p>Plastic mulching is an effective field practice to improve crop water productivity (WP), especially widely used in arid and semi-arid areas. The positive effects of soil mulching on crop yield and WP have been studied through numerous field experiments and simulations at the site scale. However, few studies have focused on the mulching effects at the regional scale. Zhangye oasis, a typical arid region in the middle Heihe River Basin, was chosen as the study area. Global sensitivity analysis was applied to determine the most sensitive parameters in AquaCrop model. Based on the results of global sensitivity analysis, soil and crop parameters of AquaCrop model were calibrated and validated using field observations from three stations. The normalized root mean square error (NRMSE) values for soil water content, seed maize canopy cover, aboveground biomass, yield, spring wheat canopy cover, aboveground biomass and yield were 18.7%, 6.7%, 23.5%, 12.5%, 10.7%, 24.2% and 15.0% during the calibration period, and the corresponding values during the validation period were 25.1%, 7.0%, 22.2%, 17.7%, 9.1%, 23.6% and 11.7%, respectively. These values indicated the calibrated model performed well to simulate the soil water content and crop growth. Compared with no-mulching, the average soil water content during the growth period, seed maize yield and WP under mulching had been increased by 8.8%, 3.0% and 3.0%, respectively. The results demonstrated that plastic mulching could effectively improve the yield and WP of seed maize, which not significantly on spring wheat. This study offers a quantitatively analysis for plastic mulching applications at the regional scale.</p>

scholarly journals Ensuring the effects of climate warming; the sensitivity of controlling factors on soil respiration in Sub-Tropical grassland

2020 ◽  
Vol 7 (3) ◽  
pp. 529-540
Author(s):  
Deepa Dhital ◽  
◽  
Suman Prajapati ◽  
Sanu Raja Maharjan ◽  
Toshiyuki Ohtsuka ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Soil Respiration ◽  
Soil Temperature ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Exponential Function ◽  
Plant Biomass ◽  
Carbon Dioxide Emission ◽  
Tropical Grassland

Prevailing climate change is expected due to carbon dioxide emission to the atmosphere through soil respiration and perhaps the alteration in the terrestrial carbon cycle. The measurements to establish the effect and sensitivity of soil temperature, soil water content and plant biomass on soil respiration was performed in the sub-tropical grassland located in Central Nepal. Field measurements of soil respiration was conducted by using the closed-chamber method, and soil temperature, soil water content and plant biomass were monitored in the years 2015 and 2016. The soil respiration showed positive significant exponential function which accounted for 74.6% (R2=0.746, p<0.05) of its variation with the soil temperature. The temperature sensitivity of soil respiration, Q10 value obtained was 2.68. Similarly, soil respiration showed a positive significant exponential function that accounted for 37.2% (R2=0.372, p<0.05) of its variation with the soil water content. Remarkable seasonal and monthly variations were observed in soil respiration, soil temperature and soil water content, and the plant biomass as well followed the seasonal trend in variation of the soil respiration. Average soil respiration during measurements period was observed 325.51 mg CO2 m-2 h-1 and the annual soil respiration of the grassland in the years 2015 and 2016 was estimated 592.35 g C m-2 y-1. The study confirmed that soil temperature is the most influential primary factor in controlling soil respiration along with the soil water content and plant biomass. This research indicates that through emissions under the increasing temperature and precipitation, in the changing climate, the sub-tropical grassland could be an additional source of carbon dioxide to the atmosphere that might spur risk for further warming.

scholarly journals A portable soil microbial fuel cell for sensing soil water content

2021 ◽  
Vol 18 ◽  
pp. 100231
Author(s):  
Hoang-Uyen-Dung Nguyen ◽  
Dang-Trang Nguyen ◽  
Kozo Taguchi
Keyword(s):  
Fuel Cell ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Microbial Fuel Cell ◽  
Soil Microbial ◽  
Soil Microbial Fuel Cell

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.

Improvements to the accuracy of modelled soil water content from the Second Generation Prairie Agrometeorological Model

2010 ◽  
Vol 90 (3) ◽  
pp. 523-526 ◽  
Author(s):  
M. Gervais ◽  
P. Bullock ◽  
M. Mkhabela ◽  
G. Finlay ◽  
R. Raddatz
Keyword(s):  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Second Generation ◽  
Regional Scale ◽  
Canadian Prairies ◽  
Growing Seasons ◽  
Crop Development ◽  
Plant Available Water ◽  
Water Values

The direct measurement of soil water on a regional scale is often not practical due to large instrumental and labour requirements. Alternatively, soil water estimates can be derived using models. The Second Generation Prairie Agrometeorological Model (PAMII) models soil water, crop development and evapotranspiration (ET) in order to derive an estimate of crop water use. The objective of this study was to validate, and if necessary modify, the soil water component of PAMII using weather and soil water data collected from several spring wheat trials in Saskatchewan and Manitoba during the 2003 though 2006 growing seasons. Comparison of modelled and measured soil water values yielded a RMSE of 62 mm. For most site-years, PAMII overestimated soil water during the second half of the growing season, which was caused by an increase in modelled canopy resistance (rc) before the crop experienced water stress. The rc function was thus modified so that rc would not increase until the soil water content was < 0.5 of plant available water. Overall this modification reduced the RMSE from 62 to 56 mm. In addition, modelled soil water was underestimated during periods that experienced consecutive days of precipitation. This was because the model stopped infiltration when the top-zone reached saturation. When modified to allow infiltration to continue independent of the top-zone’s water content, the RMSE was further reduced to 53 mm. Overall, both modifications reduced the RMSE of modelled soil water by 9 mm, and this reduction was highly significant (P < 0.01). Key words: Prairie Agrometeorological Model (PAMII), soil water modelling, evapotranspiration, Canadian prairies

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.

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