نتایج جستجو برای: soil water

تعداد نتایج: 692592  

2016
Wenjun Ji Mi Lin Asim Biswas Bing C. Si Henry W. Chau Hamish P. Cresswell

Spatiotemporal behavior of soil water is essential to understand the science of hydrodynamics. Data intensive measurement of surface soil water using remote sensing has established that the spatial variability of soil water can be described using the principle of self-similarity (scaling properties) or fractal theory. This information can be used in determining land management practices provide...

2015
Philip A. Fay Beth A. Newingham H. Wayne Polley Jack A. Morgan Daniel R. LeCain Robert S. Nowak Stanley D. Smith

The Earth's atmosphere will continue to be enriched with carbon dioxide (CO2) over the coming century. Carbon dioxide enrichment often reduces leaf transpiration, which in water-limited ecosystems may increase soil water content, change species abundances and increase the productivity of plant communities. The effect of increased soil water on community productivity and community change may be ...

Journal: :مدیریت آب و آبیاری 0
مجید هماپور گورابجیری دانشجوی سابق علوم خاک، دانشکدۀ فناوری کشاورزی، دانشگاه محقق اردبیلی علی رسول زاده استادیار گروه مهندسی آب دانشکدۀ فناوری کشاورزی دانشگاه محقق اردبیلی

soil water retention curve is one of the crucial input parameters in any modeling study on water flow and solute transport in soils. direct measurement of soil water retention curve is time-consuming and costly. alternatively, pedotransfer functions (ptfs) may be used to indirectly estimate the soil water retention curve from easily measured soil properties. many equations for the soil water re...

Journal: :Plant, cell & environment 2002
J. S. Sperry U. G. Hacke R. Oren J. P. Comstock

Many aspects of plant water use -- particularly in response to soil drought -- may have as their basis the alteration of hydraulic conductance from soil to canopy. The regulation of plant water potential (Psi) by stomatal control and leaf area adjustment may be necessary to maximize water uptake on the one hand, while avoiding loss of hydraulic contact with the soil water on the other. Modellin...

2002
S. O. Eching

Inverse solution techniques currently used for estimating unsaturated soil hydraulic functions from laboratory outflow experiments use cumulative outflow only in combination with initial and final soil water pressure head values. Additional soil water information is needed to improve the estimation procedure and to minimize uniqueness problems. It was the objective of this study to experimental...

2007
Raghavendra B. Jana Binayak P. Mohanty

Soil hydraulic properties are needed in globaland regionalscale circulation models for hydrologic and climate forecasting. They are also necessary in pointand nonpoint-source contaminant transport models. Prediction accuracy of these models is highly dependent on the quality of the model parameters. Collecting the required soil hydraulic parameters by direct measurement at any model grid scale ...

2004
Michael L. Whiting Lin Li Susan L. Ustin

This paper presents an approach to estimating soil moisture content through fitting an inverted Gaussian function to the continuum in soil spectra. The soil moisture Gaussian model (SMGM) estimates the water content by the declining reflectance in the near infrared (NIR) and shortwave infrared (SWIR) regions, 1.2–2.5 Am, due to the spreading of the fundamental water absorption at 2.8 Am. Convex...

2014
L. Ouyang F. Wang R. Zhang

The aim of this study was to investigate the effects of biochar amendment on soil aggregate formation and stability, and soil hydraulic properties. Biochar produced from dairy manure was added to two different soils (a silty clay and a sandy loam soil) at a ratio of 2% (w/w in dry weight basis). Incubation experiments were conducted within a 90-d period with the soils (the controls) and the soi...

2003
W. J. Parton Melannie Hartman

The potential sensitivity of ecological models to differences in soil temperature and soil water from land-surface models was evaluated by using model output from the PILPS land-surface model comparison. Simulated soil water and temperatures from the land-surface models were used to calculate the abiotic decomposition factor (ADF). ADF is used by ecosystem models to directly control microbial a...

Journal: :Tree physiology 2002
J Renée Brooks Frederick C Meinzer Rob Coulombe Jillian Gregg

The magnitude of hydraulic redistribution of soil water by roots and its impact on soil water balance were estimated by monitoring time courses of soil water status at multiple depths and root sap flow under drought conditions in a dry ponderosa pine (Pinus ponderosa Dougl. ex Laws) ecosystem and in a moist Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) ecosystem. The fate of deuterated wat...

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