نتایج جستجو برای: crop moisture
تعداد نتایج: 105420 فیلتر نتایج به سال:
Polarimetric Decompositions for Soil Moisture Retrieval from Vegetated Soils in TERENO Observatories
A refined hybrid polarimetric decomposition and inversion method for soil moisture estimation under vegetation is investigated for its potential to retrieve soil moisture from vegetated soils in TERENO observatories. The refined algorithm is applied on Lband fully polarimetric data acquired by DLR’s novel F-SAR sensor. Two flight and field measurement campaigns were conducted in 2011 and 2012 f...
Because of the large contrast between the dielectric constant of liquid water and that of dry soil at microwave wavelength, there is a strong dependence of the thermal emission and radar backscatter from the soil on its moisture content. This dependence provides a means for the remote sensing of the moisture content in a surface layer approximately 5 cm thick. The feasibility of these technique...
The potential of the ERS-1/2 scatterometer global soil moisture product has been shown in several studies. The ASCAT sensor on-board the METOP satellite is extending the 16 year time series of the ERS-1/2 scatterometer as a source for extracting information for ocean and land applications. Calibrated ASCAT data will continue the scatterometer global soil moisture archive while improving both th...
The objective of this work was to investigate the relationship between soil water content and rainfall with rice, beans, cassava and corn yields in the semiarid region of Northeast Brazil. Precipitation and modeled soil water content were compared to yields recorded at the county levels in this region. The results were also integrated over the area of the nine States that lie within the officia...
The southeast, despite its abundant rainfall, suffers short-term summer droughts with detrimental effect on crop yield. No-till production systems provide added insurance against such conditions by improving infiltration, and conserving moisture in drought-prone soils. In three years of experiment near Watkinsville, GA, no-till cotton treatments maintained higher soil moisture content, more veg...
Theoretical analysis of the CO(2) assimilation and water loss by single leaves suggests that the water use efficiency of C(4) species decreases as stomatal resistance increases. To confirm this hypothesis for a complete maize crop, results from computer simulations and a field experiment were compiled for varying stomatal resistances. A soil-plant-atmosphere model allowed simulations of the man...
Evapotranspiration (ET) is an important component of the hydrologic budget because it expresses the exchange of mass and energy between the soil-water-vegetation system and the atmosphere. Prevailing weather conditions influence potential or reference ET through variables such as radiation, temperature, wind, and relativity humidity. In addition to these weather variables, actual ET (ETa) is al...
Agroforestry has been widely practiced in the Loess Plateau region of China because of its prominent effects in reducing soil and water losses, improving land-use efficiency and increasing economic returns. However, the agroforestry practices may lead to competition between crops and trees for underground soil moisture and nutrients, and the trees on the canopy layer may also lead to shortage o...
Soil moisture monitoring and the characterization of the spatial and temporal variability of this hydrologic parameter at scales from small catchments to large river basins continues to receive much attention, reflecting its critical role in subsurface – land surface – atmosphere interactions and its importance to drought analysis, crop yield forecasting, irrigation planning, flood protection, ...
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