Proceedings of the 23rd annual Central Plains irrigation conference

Presented at Proceedings of the 23rd annual Central Plains irrigation conference held in Burlington, Colorado on February 22-23, 2011.Includes bibliographical references.Irrigation water management practices could greatly benefit from using soil moisture sensors that accurately measure soil water content or potential. Therefore, an assessment on soil moisture sensor reading accuracy is important. In this study, a performance evaluation of selected sensor calibration was performed considering factory- laboratory- and field-based calibrations. The selected sensors included: the Digitized Time Domain Transmissometry (TDT, Acclima, Inc., Meridian, ID) which is a volumetric soil water content sensor, and a resistance-based soil water potential sensor (Watermark 200, Irrometer Company, Inc., Riverside, CA). Measured soil water content/potential values, on a sandy clay loam soil, were compared with corresponding values derived from gravimetric samples. Under laboratory and field conditions, the factory-based calibrations for the TDT sensor accurately measured volumetric soil water content. Therefore, the use of the TDT sensor for irrigation water management seems very promising. Laboratory tests indicated that a linear calibration for the TDT sensor and a logarithmic calibration for the watermark sensor improved the factory calibration. In the case of the watermark, a longer set of field data is needed to properly establish its accuracy and reliability

Meeting irrigation demands in a water-challenged environment

Presented at Meeting irrigation demands in a water-challenged environment: SCADA and technology: tools to improve production: a USCID water management conference held on September 28 - October 1, 2010 in Fort Collins, Colorado.Includes bibliographical references.Accurate estimates of spatially distributed evapotranspiration (ET) using remote sensing inputs could help improve crop water management, the assessment of regional drought conditions, irrigation efficiency, ground water depletion, and the verification of the use of water rights over large irrigated areas. In this study, ET was mapped using surface reflectance and radiometric temperature images from the Landsat 5 satellite in a surface energy budget algorithm driven by a surface aerodynamic temperature (SAT_ET) model. The SAT_ET model was developed using surface temperature, horizontal wind speed, air temperature and crop biophysical characteristic measured over an irrigated alfalfa field in Southeastern Colorado. Estimates of the remote sensing-based ET for a 4.0 hectare alfalfa field and a 3.5 hectare oats field, during the 2009 cropping season, were evaluated using two monolithic weighing lysimeters located at the Colorado State University Arkansas Valley Research Center (AVRC) in Rocky Ford, Colorado. Although the overall model performance was encouraging, results indicated that the SAT_ET model performed well under dry atmospheric and soil conditions and less accurately under high air relative humidity and soil water content conditions. These findings are evidence that SAT_ET needs to be further developed to perform better under a range of environmental and atmospheric conditions

Elevated CO\u3csub\u3e2\u3c/sub\u3e further lengthens growing season under warming conditions

Observations of a longer growing season through earlier plant growth in temperate to polar regions have been thought to be a response to climate warming. However, data from experimental warming studies indicate that many species that initiate leaf growth and flowering earlier also reach seed maturation and senesce earlier, shortening their active and reproductive periods. A conceptual model to explain this apparent contradiction, and an analysis of the effect of elevated CO2—which can delay annual life cycle events—on changing season length, have not been tested. Here we show that experimental warming in a temperate grassland led to a longer growing season through earlier leaf emergence by the first species to leaf, often a grass, and constant or delayed senescence by other species that were the last to senesce, supporting the conceptual model. Elevated CO2 further extended growing, but not reproductive, season length in the warmed grassland by conserving water, which enabled most species to remain active longer. Our results suggest that a longer growing season, especially in years or biomes where water is a limiting factor, is not due to warming alone, but also to higher atmospheric CO2 concentrations that extend the active period of plant annual life cycles

Introduction to Special issue of \u3ci\u3eIrrigation Science\u3c/i\u3e: Improving irrigation management across the Ogallala aquifer, USA

Groundwater stored in aquifers is a major source of irrigation water for many agricultural regions that receive insufficient precipitation for crop production. In the U.S.A., the High Plains aquifer (HPA) that underlies parts of Colorado, Kansas, Nebraska, New Mexico, Oklahoma, South Dakota, Texas, and Wyoming supplies irrigation water for agricultural production. The HPA underlies around 450,658 km2 (174,000 mi2) of which the Ogallala aquifer is the principal geologic formation underlying 347,059 km2 (134,000 mi2) (Gutentag et al. 1984). The Ogallala aquifer is primarily a water table (unconfined) aquifer with saturated thickness ranging from 0 m to about 366 m (McGuire 2017). Average annual precipitation ranges from 400 mm in the west to 800 mm in the east of the Ogallala aquifer region (OAR), while mean annual pan evaporation ranges from 1500 mm in the north to 2700 mm in the south of the OAR (Zhang et al. 2019). The papers in this special issue report results of collaborative research primarily supported by the United States Department of Agriculture (USDA)-National Institute of Food and Agriculture Ogallala Water Coordinated Agriculture Project (CAP) that bring together researchers from more than ten institutions across six States in the OAR (https://ogallalawater.org/). The nine papers cover a broad range of irrigation management topics under two main categories as follows

Proceedings of the 23rd annual Central Plains irrigation conference

Presented at Proceedings of the 23rd annual Central Plains irrigation conference held in Burlington, Colorado on February 22-23, 2011.Includes bibliographical references

AGU hydrology days 2013

2013 annual AGU hydrology days was held at Colorado State University on March 25 - March 27, 2013.Includes bibliographical references.Accurate estimation of crop evapotranspiration (ET) is important to know how much water is required during the growing season, to improve crop water management, to conserve soil and water resources and for water rights purposes. Various forms of semi-empirical equations have been developed to estimate crop ET. The ASCE-EWRI Standardized Penman-Monteith (PM) equation and the full version of the Penman-Monteith equation have been used in this study to estimate alfalfa ET. The ASCE-EWRI Standardized PM equation along with crop coefficients (Kc) can be used to estimate actual crop ET. The full version of the PM equation can be applied to calculate actual ET directly for unstressed crop conditions using weather and crop variables. In this study, both PM ET methods were evaluated using a monolithic precision weighing lysimeter. The research was carried out at the Colorado State University- Arkansas Valley Research Center, Rocky Ford, Colorado. Data from 2009 and 2010 from a large precision monolithic weighing lysimeter were used. The performance evaluation of the PM equations was done for different atmospheric stability conditions. The statistical analysis included the mean absolute error, mean biased error, root mean squared error, linear regression slope-intercept (and goodness of fit), and the index of agreement. The evaluation was done using days where the alfalfa was at reference conditions. The results showed that both PM ET methods compared satisfactorily with the lysimeter ET values, however, both methods underestimated actual alfalfa ET. It was also observed that the bias was larger in unstable than in stable atmospheric condition for both methods

Elevated CO\u3csub\u3e2\u3c/sub\u3e further lengthens growing season under warming conditions

Observations of a longer growing season through earlier plant growth in temperate to polar regions have been thought to be a response to climate warming. However, data from experimental warming studies indicate that many species that initiate leaf growth and flowering earlier also reach seed maturation and senesce earlier, shortening their active and reproductive periods. A conceptual model to explain this apparent contradiction, and an analysis of the effect of elevated CO2—which can delay annual life cycle events—on changing season length, have not been tested. Here we show that experimental warming in a temperate grassland led to a longer growing season through earlier leaf emergence by the first species to leaf, often a grass, and constant or delayed senescence by other species that were the last to senesce, supporting the conceptual model. Elevated CO2 further extended growing, but not reproductive, season length in the warmed grassland by conserving water, which enabled most species to remain active longer. Our results suggest that a longer growing season, especially in years or biomes where water is a limiting factor, is not due to warming alone, but also to higher atmospheric CO2 concentrations that extend the active period of plant annual life cycles

Strategic and Tactical Prediction of Forage Production in Northern Mixed-Grass Prairie

Predictions of forage production derived from site-specific environmental information (e.g., soil type, weather, plant communitycomposition, and so on) could help land managers decide on appropriate stocking rates of livestock. This study assessed the applicability of the Great Plains Framework for Agricultural Resource Management (GPFARM) forage growth model for both strategic (long-term) and tactical (within-season) prediction of forage production in northern mixed-grass prairie. An improved version of the model was calibrated for conditions at the USDA-ARS High Plains Grasslands Research Station in Cheyenne, Wyoming. Long-term (1983-2001) simulations of peak standing crop (PSC) were compared to observations. Also, within-season (1983) forecasts of total aboveground biomass made for 1 March onward, 1 April onward, 1 May onward, and 1 June onward were compared to observations. The normal, driest, and wettest weather years on record (1915-1981) were used to simulate expected values, lower bounds, and upper bounds of biomass production, respectively. The forage model explained 66% of the variability in PSC from 1983 to 2001. The cumulative distribution function (CDF) derived from long-term simulated PSC overestimates cumulative probabilities for PSC.1 500 kg ha-1. The generated CDF could be used strategically to estimate long-term forage production at various levels of probability, with errors in cumulative probability ranging from 0.0 to 0.16. Within-season forecasts explained 77%-94% of biomass variability in 1983. It was shown that monthly updating of the forage forecast, with input of actual weather to date, improves accuracy. Further development and testing of the forage simulation model will focus on the interactions between forage growth, environmental perturbations (especially drought), and grazing.The Rangeland Ecology & Management archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform August 2020Legacy DOIs that must be preserved: 10.2458/azu_jrm_v59i6_andale

052 - AJ Joseph Brown

This poster was presented at the 2017 Annual Graduate Student Showcase and received an honorable mention for the "Greatest Minds In Research" award.Includes bibliographical references.Global salinization of irrigated lands results in a $12 billion (US) reduction in global crop production annually. A joint effort between Utah State University, Colorado State University, and Mehran University in Pakistan aimed to investigate the impacts and movement of salts in agronomic systems, and identify common solutions. This was done through water and soil monitoring in Southeast Colorado in a surface irrigation setting. Results indicated that salts are loaded onto fields because of saline water, and get trapped in root zones by shallow water tables. The added salt decreases osmotic potential in soil, making root water uptake more difficult.Great Minds in Research - Honorable Mention

Soil water content sensors

Presented at Emerging challenges and opportunities for irrigation managers: energy, efficiency and infrastructure: a USCID water management conference held on April 26-29, 2011 in Albuquerque, New Mexico.Includes bibliographical references.This study evaluated the performance of digitized Time Domain Transmissometry (TDT) soil water content sensors (Acclima, Inc., Meridian, ID) and resistance-based soil water potential sensors (Watermark 200, Irrometer Company, Inc., Riverside, CA) in two soils. The evaluation was performed by comparing volumetric water content (θv) data collected in the laboratory and in fields near Greeley, CO, with values measured by the sensors. Calibration equations of θv were then developed based on the laboratory and field data. Statistical targets to determine accuracy of the equations were ±0.015 m³ m⁻³ mean bias error and a root mean square error of less than 0.020 m³ m⁻³. Under laboratory and field conditions, the factory-based calibrations of θv did not consistently achieve the required accuracy for either sensor. Field tests indicated that using the calibration equation developed in the laboratory to correct data obtained by TDT and Watermark sensors in the field at Site A (sandy clay loam) was not consistently accurate. Using the laboratory equations developed for the Watermark sensors at Site B (loamy sand) accurately measured θv. Field tests found that a linear calibration of the TDT sensors (and a logarithmic calibration for the Watermark sensors) could accurately correct the factory calibration of θv in the range of permanent wilting point (PWP) to field capacity (FC). Furthermore, the van Genuchten (1980) equation was not significantly more accurate than the logarithmic equation, and the additional work of deriving the former equation did not seem worthwhile, within the range of soil water contents analyzed