to study the effect of soil moisture variation on growth and steviol glycosides contents in stevia (stevia rebaudiana b), a potexperiment based on a randomized complete design with four treatments and three replications were conducted in a greenhouse of agricultural biotechnology research institute of iran (central region, isfahan), in 2012. experimental treatments applied as a combination of v...

Methyl bromide (CH,Br) is currently the most widely used soil fumigant, and its emission into the atmosphere after application reportedly contributes to ozone depletion in the stratosphere. Irreversible degradation and partially reversible sorption reactions affect the quantity of this fumigant reaching the soil surface and escaping into the atmosphere. Incubation studies in closed headspace vi...

The electrical conductivity (EC) of soil is generally measured after soil extraction, so this method cannot represent the in situ EC of soil (e.g., EC of soils with different moisture contents) and therefore lacks comparability in some cases. Using a resistance measurement apparatus converted from a configuration of soil microbial fuel cell, the in situ soil EC was evaluated according to the Oh...

Accurate soil moisture content measurements are vital to precision irrigation management. Remote sensing using the microwave spectrum (such as GPS signals) has been used for measuring large area soil moisture contents. In our previous work, we estimated surface soil moisture contents for bare soil using a GPS Delay Mapping Receiver (DMR) developed by NASA. However, the effect of vegetation was ...

The Tau-Omega model of microwave emission from soil and vegetation layers is widely used to estimate soil moisture content from passive microwave observations. Its application to prospective satellite-based observations aggregating several thousand square kilometres requires understanding of the effects of scene heterogeneity. The effects of heterogeneity in soil surface roughness, soil moistur...

Soil moisture retrieval from SAR images using semi-empirical or physically-based backscatter models requires surface roughness parameters, generally obtained by means of in situ measurements. However, measured roughness parameters often result in inaccurate soil moisture contents. Furthermore, when these retrieved soil moisture contents need to be used in data assimilation schemes, it is import...

Soil is a mixture of four components: air, free water, bound water and soil particles. The microwave dielectric constant of soil is strongly dependent on the soil moisture content. The dielectric constant is a measure of the response of a material to an applied electric field, such as an electromagnetic wave. It has a real and an imaginary component. Soil particles’ dielectric constant depends ...

Comparisons to ground-based surface soil moisture estimates are necessary to evaluate the capability of remote sensors to determine soil moisture and its spatiotemporal variability. Soil moisture can be especially variable in regions of complex terrain which exhibit large variations in vegetation, soil properties and hydrologic conditions. The objective of this study is to evaluate the spatiote...

Root zone soil moisture is a key variable in many land surface hydrology models. Often, however, there is a mismatch in the spatial scales at which models simulate soil moisture and at which soil moisture is observed. This complicates model validation. The increased availability of detailed datasets on space-time variability of root-zone soil moisture allows for a posteriori analysis of the unc...

Accumulation of beef cattle manure on feedlot pen surfaces generates large amounts of dissolved solutes that can be mobilized by water fluxes, affecting surface and groundwater quality. Our objective was to examine the long-term impacts of a beef cattle feeding operation on water fluxes and manure leaching in feedlot pens located on sandy loam soils of the subhumid Sandy Pampa region in Argenti...