Estimation of soil water deficit in an irrigated cotton field with infrared thermography

Plant growth and soil water deficit can vary spatially and temporally in crop fields due to variation in soil properties and/or irrigation and crop management factors. We conducted field experiments with cotton (Gossypium hirsutum L.) over two seasons during 2007-2009 to test if infrared thermography can distinguish systematic variation in deficit irrigation applied to various parts of the field over time. Soil water content was measured with a neutron probe and thermal images of crop plants were taken with a thermal infrared camera. Leaf water potential and stomatal conductance were also measured on selected occasions. All measurements were made at fixed locations within three replicate plots of an irrigation experiment consisting of four soil-water deficit treatments. Canopy temperature related as well with soil water within the root zone of cotton as the stomatal conductance index derived from canopy temperature, but it neglected the effect of local and seasonal variation in environmental conditions. Similarities in the pattern of spatial variation in canopy temperature and soil water over the experimental field indicates that thermography can be used with stomatal conductance index to assess soil water deficit in cotton fields for scheduling of irrigation and to apply water in areas within the field where it is most needed to reduce water deficit stress to the crop. Further confidence with application of infrared thermography can be gained by testing our measurement approach and analysis with irrigation scheduling of other crops

El derecho de autodeterminación nacional: ¿un derecho humano?

Este artículo tratará de responder a la cuestión de si cabe aplicar la categoría derechos humanos a la autodeterminación de los pueblos. Para ello se analizarán los argumentos más importantes que la doctrina utiliza para negar la inclusión de la autodeterminación entre los derechos humanos, tratando de determinar si cabe un razonamiento alternativo. This article aims at determining whether self-determination of peoples can be considered a human right. To do it, the main arguments scholars use to reject the inclusion of self-determination among human rights will be evaluated, and the possibilities of an alternative line of reasoning will be explored

Mapping and Characterization of Center Pivot and Lateral Move Irrigation Systems in South Carolina Using Quantum Geographic Information System

In recent decades, the adoption of overhead irrigation systems, especially center pivots, to irrigate row crops has been steadily increasing in South Carolina. The adoption of irrigation in the state has been enhanced by the predominance of coarse-textured soils with low water-holding capacities, which increases the likelihood of obtaining a significant and profitable crop yield response to irrigation. As the number of overhead irrigation systems in the state increases, it is vital to understand their number, location, and characteristics for better planning and managing available water resources. The objective of this project was to map and characterize the overhead irrigation systems (center pivots and lateral moves) available in each county in South Carolina. The Quantum Geographic Information System (QGIS) was used to manually locate and measure each overhead irrigation system in the state using a 2022 Google satellite image. Basic measurements included the length, number of spans, and wetted radius. In addition, the rotation angle of center pivots and the field length of lateral move systems were measured. This study found that with a few exceptions, the overwhelming majority of the overhead irrigation systems in the state were located in the central part of the Coastal Plain region, between the Fall Line and the coast, where groundwater resources are more abundant. Also, this study found a total of 2,980 center pivots and 15 lateral move irrigation systems in South Carolina. A total of 64,694 hectares were irrigated by center pivots, while lateral moves irrigated only 80 hecatares. Out of the 46 counties in the state, those with the highest number of center pivots were Orangeburg (633 pivots), Calhoun (361), Lee (296), Clarendon (249), Sumter (248), Lexington (197), Bamberg (130), Darlington (121), Hampton (117), and Barnwell (114). All the lateral move systems were located in the counties of Barnwell (11) and Darlington (4). Water stakeholders and agencies in South Carolina could use this information for long-term water resources planning at various levels. This research is also useful nationally to inform the understanding of irrigation practices in the southeastern United States

Demonstrating subsurface drip irrigation as a climate adaptation strategy for sustainable crop production in South Carolina

2014 S.C. Water Resources Conference - Informing Strategic Water Planning to Address Natural Resource, Community and Economic Challenge

Use of time domain reflectometry for continuous monitoring of nitrate-nitrogen in soil and water

Nitrate-Nitrogen (NO3-N) losses to ground and surface water are an environmental and agronomic concern in modern crop production systems in the Central Great Plains. Monitoring techniques for nitrogen use in agricultural production are needed to increase crop yield, optimize nitrogen use, and reduce NO3-N leaching. Time domain reflectometry (TDR) could potentially be calibrated to continuously measure NO3-N in soil and water. The objectives of this study were to: (1) evaluate the effect of different factors affecting the response of the bulk electrical conductivity (ECb) sensed by TDR, (2) compare the sensitivity and differences between vertically-installed and horizontally-installed probes for measuring NO3-N leaching in the soil profile, and (3) evaluate the feasibility of using TDR to measure changes in NO3-N concentration in an irrigated agricultural soil. Studies were conducted in the laboratory and in the field at the University of Nebraska West Central Research and Extension Center in North Platte, Nebraska. Temperature of the medium (Ts), solute concentration, TDR cable length, and volumetric soil water content (0v) all influenced and were linearly related to the bulk electrical conductivity (ECb) sensed by the TDR probes. In the field, measured soil NO3-N correlated well with values estimated using TDR measurements of ECb, corrected for changes in 0v and Ts. These results indicated that TDR, if properly calibrated for a particular soil, could be used to continuously monitor NO3-N in soil, and should also be well-suited for monitoring NO3-N in groundwater and surface water. It is, however, important to perform the calibration over a long enough period of time to include the expected range of 0v, Ts, and NO3-N values to obtain adequate accuracy

Maximising profitability with limited water in cotton farming systems

Diminishing water supply, changing weather patterns and pressure to enhance environmental flows are making it imperative to optimise water use efficiency (WUE) on cotton/grain farming systems. Growers are looking for better strategies to make the best use of limited water, but it is still not clear how to best use the available water at farm and field scale. This research project investigated the impact of management strategies to deal with limited water supplies on the yield and quality of irrigated cotton and wheat. The objectives were: (1) to develop irrigation management guidelines for the main irrigated crops on the Darling Downs for full- and deficitirrigation scenarios, taking into account the critical factors that affect irrigation decisions at the local level, (2) to quantify the evapotranspiration (ET) of Bollgard II cotton and wheat and its relationship to yield and quality under full- and deficit-irrigation scenarios, and (3) to increase industry awareness and education of farming systems practises for optimised economic water use efficiency.Objective (1) was addressed by (A) collaborating with ASPRU to develop the APSFarm model within APSIM to be able to perform multi-paddock simulations. APSFarm was then tested by conducting a case study at a farm near Dalby, and (B) conducting semi-structured interviews with individual farmers and crop consultants on the Darling Downs to document the strategies they are using to deal with limited water. Objective (2) was addressed by (A) building and installing 12 large (1 m x 1m x 1.5 m) weighing lysimeters to measure crop evapotranspiration. The lysimeters were installed at the Agri-Science Queensland research station at Kingsthorpe in November 2008, (B) conducting field experiments to measure crop evapotranspiration and crop development under four irrigation treatments, including dryland, deficit-irrigation, and full irrigation. Field experiments were conducted with cotton in 2007-08 and 2008-09, and with wheat in 2008 and 2009, and (C) collaborating with USQ on a PhD thesis to quantify the impact of crop stress on crop evapotranspiration and canopy temperature. Glasshouse experiments were conducted with wheat in 2008 and with cotton in 2008-09. Objective (3) was addressed by (A) conducting a field day at Kingsthorpe in 2009, which was attended by 80 participants, (B) presenting information in conferences in Australia and overseas, (D) presenting information at farmers meeting, (E) making presentations to crop consultants, and (F) preparing extension publications.As part of this project we contributed to the development of APSfarm, which has been successfully applied to evaluate the feasibility of practices at the whole-farm scale. From growers and crop consultants interviews we learned that there is a great variety of strategies, at different scales, that they are using to deal with limited water situation. These strategies will be summarised in the &quote;Limited Water Guidelines for the Darling Downs&quote; that we are currently preparing. As a result of this project, we now have a state-of-the-art lysimeter research facility (23 large weighing lysimeters) to be able to conduct replicated experiments to investigate daily water use of a variety of crops under different irrigation regimes and under different environments. Under this project, a series of field and glasshouse experiments were conducted with cotton and wheat, investigating aspects like: (A) quantification of daily and seasonal crop water use under nonstressed and stressed conditions, (B) impact of row configuration on crop water use, (C) impact of water stress on yield, evapotranspiration, crop vegetative and reproductive development, soil water extraction pattern, yield and yield quality. The information obtained from this project is now being used to develop web-based tools to help growers make planning and day-to-day irrigation decisions

Nonvolcanic tremor observed in the Mexican subduction zone

Nonvolcanic tremor (NVT) activity is revealed as episodes of higher spectral amplitude at 1–8 Hz in daily spectrograms from the continuous seismological records in Guerrero, Mexico. The analyzed data cover a period of 2001–2007 when in 2001–2002 a large slow slip event (SSE) had occurred in the Guerrero-Oaxaca region, and then a new large SSE occurred in 2006. The tremor burst is dominated by S-waves. More than 100 strong NVT bursts were recorded in the narrow band of ~40 × 150 km^2 to the south of Iguala City and parallel to the coastline. Depths of NVT hypocenters are mostly scattered in the continental crust between 5 and 40 km depth. Tremor activity is higher during the 2001–2002 and 2006 SSE compared with that for the “quiet” period of 2003–2005. While resistivity pattern in Guerrero does not correlate directly with the NVT distribution, gravity and magnetic anomaly modeling favors a hypothesis that the NVT is apparently related to the dehydration and serpentinization processes