Search results for " water content"

Coupling two radar backscattering models to assess soil roughness and surface water content at farm scale

2013

Remote sensing techniques are useful for agro-hydrological monitoring at the farm scale because the availability of spatially and temporally distributed data improves agricultural models for irrigation and crop yield optimization under water scarcity conditions. This research focuses on the surface water content retrieval using active microwave data. Two semi-empirical models were chosen as these showed the best performances in simulating cross and co-polarized backscatter. Thus, these models were coupled to obtain reliable assessments of both soil water content and soil roughness. The use of the coupled model enables one to avoid using roughness measured in situ. Remote sensing images and …

Growth and biomass partitioning of Arbutus unedo, Laurus nobilis, Phillyrea angustifolia and Rhamnus alaternus seedlings under water deficit

2013

Water scarcity in the Mediterranean areas is very common and the selection of drought tolerant species is a priority for landscaping purposes in the Mediterranean areas. The objective of this study was to evaluate the effect of water deficit on growth and biomass partitioning of Arbutus unedo, Laurus nobilis, Phillyrea angustifolia and Rhamnus alaternus. Seventy-two seedlings per species were grown in the greenhouse in 4-liter pots and three water regimes were imposed starting on 6 April and until 9 June, 2010. One-third of the plants was well irrigated to maintain soil water content in the 25-35% range (CTR); a second group of plants was deficit-irrigated to maintain soil water content in …

Effects of tilling methods on soil penetration resistance, organic carbon and water stable aggregates in a vineyard of semiarid Mediterranean environ…

2018

Tillage, especially in semiarid Mediterranean environment, enhances the mineralization process of soil organic matter (SOM) and, in turn, decreases aggregate stability. Furthermore, continuous tillage leads to the formation of plough pan beneath the tilled layer. In the present study, we investigated the effect of an innovative self-propelled machine (spading machine, SM) for shallow tillage on SOM, water stable aggregates (WSA) and soil penetration resistance (PR). Such effects were compared to those of chisel plough (CP), rotary tiller (RT) and no tillage (NT). Each tilling method was applied up to a depth of 15 cm, whereas in NT only a brush cutter was used for weed control. Soil analyse…

Response of transgenic mannitol-producing tobacco plants to water deficit

2008

Transgenic mannitol-producing (+mtlD) and wild type (-mtlD) tobacco plants were exposed to water deficit to test whether mannitol is involved in drought stress protection. Rooted cuttings of -mtlD and +mtlD plants were fully irrigated (100% ET) or received 25% ET for 40 days, followed by 20 days of re-watering. Water deficit reduced RWC of both plant types starting on the 22nd day, total stem length of -mtlD 25% ET already after 11 days, whereas that of +mtlD 25% ET only after 34 days. After 30 days of deficit, a greater percentage of mature foliage was retained by +mtlD 25% ET compared to -mtlD 25% ET. Mannitol-1-phosphate dehydrogenase activity of +mtlD plants was not affected by water de…

Assessing the performance of different model-based techniques to estimate water content in the upper soil layer

2016

he knowledge of soil water content (SWC) of the upper soil layer is important for most hydrological processes occurring over vegetated areas and under dry climate. Because direct field measurements of SWC are difficult, the use of different type of sensors and model-based approaches have been proposed and extensively used during the last decade. The main objective of this work is to assess the performance of two models estimating SWC of the upper soil layer: the transient line heat source method and the physically based Hydrus-1D model. The models' performance is assessed using field measurements acquired through a Time Domain Reflectometer (TDR). The experiment was carried out on an olive …

Regional Soil Moisture Retrieval Using Remotely Sensed Crop Water Stress Indicators

2011

Mapping soil water content under sparse vegetation and changeable sky conditions: comparison of two thermal inertia approaches

2013

A critical analysis of a thermal inertia approach to map surface soil water content on bare and sparsely vegetated soils by means of remotely sensed data is reported. The study area is an experimental field located in Barrax, Spain. In situ data were acquired within the Barrax 2011 research project. An advanced hyperspectral scanner airborne imager provides images in the visible/near-infrared and thermal infrared bands. Images were acquired both in day and night times by the Instituto Nacional de Técnica Aeroespacial between 12th and 13th of June 2011. The scene covers a corn irrigation pivot surrounded by bare soil, where a set of in situ data have been collected both previously and simult…