Comparison of site-specific and conventional uniform irrigation management for potatoes

Site-Specific Irrigation Management (SSIM) can be defined as irrigation management (depth, timing) based on crop need to defined sub-areas of a field referred to as management zones. Implementation of SSIM will require additional irrigation system hardware, labor, and information on soil and/or plant water status in each management zone. Costs associated with these additional requirements will need to be offset by increased receipts from improved crop yield and quality in order for the technology to be adopted by producers. The potential for SSIM to increase crop yield, quality, and economic return has not been evaluated in field studies. Crops such as potatoes, for which yield and quality are highly sensitive to soil water availability, are most likely to show an economic benefit from site-specific irrigation management. A two-year field study was conducted to evaluate the potential for SSIM to increase yield and quality of potatoes relative to Conventional Uniform Irrigation Management (CUIM). Near real-time soil water content was used to schedule irrigations under both irrigation management treatments. Field average water application was nearly the same for the irrigation management treatments, 503 mm (19.8 in.) in 2001 and 445 mm (17.5 in.) in 2002. In both study years, tuber yield distributions trended 4% greater under site-specific irrigation management but were not significantly different (p < 0.05). Total tuber yield per unit of water applied from irrigation and precipitation was 4% greater in 2001 and 6% greater in 2002 under SSIM. Based on a local tuber quality adjusted potato processing contract price structure, the trend in gross income averaged across the field site was $159/ha ($65/acre) greater with SSIM. This increase in gross income is likely about half the actual cost of commercial site-specific irrigation technology. The required 3- to 5-year crop rotation for potato disease management means that the site-specific irrigation system needs to be mobile or an economic benefit must also be realized from other crops in the rotation. The economic benefit of SSIM needs to be increased or realized for other crops in the rotation for it to be an economically viable technology in potato production systems in Idaho

Center-pivot irrigation system for independent site-specific management of water and chemical application

The development of lateral?move and center?pivot irrigation systems equipped for spatially variable water application and those equipped with an independent chemical application system have largely evolved independently. Integration of independent site?specific water and chemical application with lateral?move and center?pivot irrigation systems has received little attention. Increasing the utility of site?specific management technologies added to automated irrigation systems will increase their cost effectiveness and commercial potential. An independent chemical application system capable of variable rate application was installed and tested on a 4?span center?pivot irrigation system equipped for variable rate water application. The chemical application system was assembled using mini?sprinklers and common commercial irrigation system components. For uniform chemical application, the coefficient of uniformity (CU) values ranged from 84 to 90 providing acceptable application uniformity. For variable rate chemical application, CU values ranged from 79 to 93 and measured mean area?weighted relative application values were well correlated with target relative application values with R2 of 0.9 or higher. Field testing of the chemical application system demonstrated that it can be used to effectively apply spatially variable chemical application concurrent and independent of spatially variable water application

Spatially distributed control netowork for flow proportional chemical injection with center pivot irrigation

The agricultural production practice of injecting a chemical into an operating irrigation system and applying it to the field area with the water is known as chemigation. Chemigation is a widely adopted practice with center pivot sprinkler irrigation. However, the practice of chemical injection at a constant rate with center pivot sprinkler irrigation systems equipped with an end gun and/or swing?arm corner watering system results in systematic chemical application errors ranging from 7% to 21% due to systematic changes in system flow rate. Chemical injection proportional to center pivot sprinkler system flow rate is one approach to reduce systematic chemical application errors. The objective of this project was to test the feasibility of using real?time monitoring of center pivot sprinkler irrigation system operating status to control chemical injection rate proportional to calculated system flow rate, thus minimizing systematic chemical application errors. A spatially distributed control network was developed to facilitate real?time monitoring of end gun and swing?arm corner watering system operating status and pressure. The spatially distributed control network consisted of three network nodes at specific locations along a center pivot sprinkler irrigation lateral that used the 480 VAC 3?phase power cable on the center pivot sprinkler irrigation system as the communication medium. The spatially distributed control network was installed on a commercial 460?m (1510?ft) long center pivot sprinkler system equipped with an end gun and swing?arm corner watering system. Performance of chemical injection proportional to calculated flow rate based on real?time center pivot sprinkler irrigation system operating status was evaluated by injecting Rhodamine WT dye into the center pivot sprinkler irrigation system water supply and measuring its concentration in the applied water. Mean dye concentration varied by 26% under constant rate chemical injection and 2% under flow proportional chemical injection due to systematic changes in center pivot sprinkler irrigation system flow rate. Use of the flow proportional chemical injection system reduced the coefficient of variability in measured dye concentration of applied water by 54% from 0.100 to 0.046. Use of the spatially distributed control network for calculating center pivot sprinkler system flow rate eliminates the need for straight sections of unobstructed piping at the chemical injection site. Display and/or data logging of real?time center pivot sprinkler operating status is an added benefit of using the spatially distributed control network. This information provides the ability to monitor, diagnose, and troubleshoot center pivot sprinkler system operation. Commercialization and adoption of the technology could reduce systematic chemical application errors and facilitate maintenance and operation of center pivot sprinkler irrigation systems equipped with an end gun and/or swing?arm corner watering system

Collector design for measuring high intensity time variant sprinkler application rates

Peak water application rate in relation to soil water infiltration rate and soil surface storage capacity is important in the design of center pivot sprinkler irrigation systems for efficient irrigation and soil erosion control. Measurement of application rates of center pivot irrigation systems has traditionally used tipping bucket rain gauges. Calculation of application rate from tipping bucket rain gauge measurements restricts computed application rate to a discrete multiple of the rain gauge resolution and time interval. This limits the resolution of application rate measurement, especially for time intervals less than 15 minutes. A collector was designed to measure time variant high intensity sprinkler application rates under field conditions with greater resolution than a tipping bucket rain gauge. The collector funnels water into a 50 mm (2 in.) diameter tube providing a depth multiplication factor of 18.26:1. The depth of water in the tube is measured with a low pressure piezo-resistive pressure sensor connected to a differential amplifier circuit. Combination of the depth multiplication factor of the collector and differential amplifier circuit provides a collector resolution of 1.4 mm/mV. A data logger is used to record water depth in the collector tube during an irrigation event. A digital differentiating filter was designed and used to reduce the effect of random electrical noise in the sensor output on calculated application rate. The collector was tested in the laboratory and under field conditions emulating center pivot sprinkler irrigation. For a range in application rates from 15 to 200 mm/h in the laboratory, the maximum collector error was 2.1 mm/h. Collector measured application rate patterns under field conditions were well correlated to simulated application rate patterns using radial application rate profiles for the sprinklers tested. Collector measured peak application rates were not significantly different from those predicted by the Kincaid (2005) model. The collector functioned as designed in field tests and provided an effective and efficient means of measuring high intensity application rates from center pivot irrigation systems under field conditions

Field scale performance of a variable rate sprinkler for variable water and nutrient application

A 3-span linear-move irrigation system was equipped with 32 prototype variable rate sprinklers. Water application uniformity was measured over a 2.7X range in application rate. The measured application uniformity was 90% or greater for all water application rates. Variable rate nitrogen application was evaluated on a 1.1 ha area. Variable rate nitrogen application was within 4% of target application. The variable rate sprinkler allows variable rate water application with minimal effect on water application uniformity

Field testing of a variable rate sprinkler and control system for site-specific water and nutrient application

Development and implementation of site-specific sprinkler irrigation management has been limited due to the lack of variable rate sprinklers. Thirty-two prototype variable rate sprinklers were constructed and field tested on a three-span linear-move irrigation system. An algorithm was developed for a distributed control network to allow each sprinkler to be individually controlled in groups of six or seven along the linear-move lateral. Water application uniformity was monitored over a 36% to 100% range in application rate. Measured application uniformity equaled or exceeded 90%. Variable rate nitrogen application was monitored over a 1.1-ha area. Measured nitrogen application rate was within 4% of the target application rate. Results indicate that the prototype variable rate sprinkler and control system allows water and chemical application to vary over a 36% to 100% range in application rate with minimal effect on water application uniformity

Single electron magneto-conductivity of a nondegenerate 2D electron system in a quantizing magnetic field

We study transport properties of a non-degenerate two-dimensional system of non-interacting electrons in the presence of a quantizing magnetic field and a short-range disorder potential. We show that the low-frequency magnetoconductivity displays a strongly asymmetric peak at a nonzero frequency. The shape of the peak is restored from the calculated 14 spectral moments, the asymptotic form of its high-frequency tail, and the scaling behavior of the conductivity for omega -> 0. We also calculate 10 spectral moments of the cyclotron resonance absorption peak and restore the corresponding (non-singular) frequency dependence using the continuous fraction expansion. Both expansions converge rapidly with increasing number of included moments, and give numerically accurate results throughout the region of interest. We discuss the possibility of experimental observation of the predicted effects for electrons on helium.Comment: RevTeX 3.0, 14 pages, 8 eps figures included with eps

Search for displaced vertices arising from decays of new heavy particles in 7 TeV pp collisions at ATLAS

We present the results of a search for new, heavy particles that decay at a significant distance from their production point into a final state containing charged hadrons in association with a high-momentum muon. The search is conducted in a pp-collision data sample with a center-of-mass energy of 7 TeV and an integrated luminosity of 33 pb^-1 collected in 2010 by the ATLAS detector operating at the Large Hadron Collider. Production of such particles is expected in various scenarios of physics beyond the standard model. We observe no signal and place limits on the production cross-section of supersymmetric particles in an R-parity-violating scenario as a function of the neutralino lifetime. Limits are presented for different squark and neutralino masses, enabling extension of the limits to a variety of other models.Comment: 8 pages plus author list (20 pages total), 8 figures, 1 table, final version to appear in Physics Letters

Measurement of the polarisation of W bosons produced with large transverse momentum in pp collisions at sqrt(s) = 7 TeV with the ATLAS experiment

This paper describes an analysis of the angular distribution of W->enu and W->munu decays, using data from pp collisions at sqrt(s) = 7 TeV recorded with the ATLAS detector at the LHC in 2010, corresponding to an integrated luminosity of about 35 pb^-1. Using the decay lepton transverse momentum and the missing transverse energy, the W decay angular distribution projected onto the transverse plane is obtained and analysed in terms of helicity fractions f0, fL and fR over two ranges of W transverse momentum (ptw): 35 < ptw < 50 GeV and ptw > 50 GeV. Good agreement is found with theoretical predictions. For ptw > 50 GeV, the values of f0 and fL-fR, averaged over charge and lepton flavour, are measured to be : f0 = 0.127 +/- 0.030 +/- 0.108 and fL-fR = 0.252 +/- 0.017 +/- 0.030, where the first uncertainties are statistical, and the second include all systematic effects.Comment: 19 pages plus author list (34 pages total), 9 figures, 11 tables, revised author list, matches European Journal of Physics C versio

Observation of a new chi_b state in radiative transitions to Upsilon(1S) and Upsilon(2S) at ATLAS

The chi_b(nP) quarkonium states are produced in proton-proton collisions at the Large Hadron Collider (LHC) at sqrt(s) = 7 TeV and recorded by the ATLAS detector. Using a data sample corresponding to an integrated luminosity of 4.4 fb^-1, these states are reconstructed through their radiative decays to Upsilon(1S,2S) with Upsilon->mu+mu-. In addition to the mass peaks corresponding to the decay modes chi_b(1P,2P)->Upsilon(1S)gamma, a new structure centered at a mass of 10.530+/-0.005 (stat.)+/-0.009 (syst.) GeV is also observed, in both the Upsilon(1S)gamma and Upsilon(2S)gamma decay modes. This is interpreted as the chi_b(3P) system.Comment: 5 pages plus author list (18 pages total), 2 figures, 1 table, corrected author list, matches final version in Physical Review Letter