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• 1. [Article] Optimal irrigation management : a framework, model, and application for optimizing irrigation when supplies are limited

  Many regions in North America are experiencing water shortages, and these conditions are expected to worsen. The next generation of irrigation scheduling applications must therefore be capable of providing ...

  Citation × Citation Citation Abstract Copy Title: Optimal irrigation management : a framework, model, and application for optimizing irrigation when supplies are limited Author: Hillyer, Charles C. (Charles Carter) Many regions in North America are experiencing water shortages, and these conditions are expected to worsen. The next generation of irrigation scheduling applications must therefore be capable of providing operational advice in support of deficit irrigation strategies. However, the theoretical, technical, and practical challenges associated with deficit irrigation scheduling are far more complex than conventional (full) irrigation. This dissertation presents three distinct systems for addressing the analytical challenges of deficit irrigation management. The first section of the dissertation presents a simulation framework for agro-ecological simulation. The objective was to develop a method to enable the assembly of simulation models from previously and independently developed component models. Based on a requirements analysis of existing simulation models we developed the ModCom simulation framework. ModCom provides a set of interface specifications that describe components in a simulation. ModCom also provides implementations of the core simulation services. The framework interfaces use well-defined binary standards and allows developers to implement the interfaces using a broad range of computer languages. The Second section describes the Irrigation Efficiency Model (IEM). IEM explicitly analyzes irrigation efficiency, accounts for spatial variability of soil properties and irrigation uniformity, performs simultaneous scheduling for all fields in the farm, accounts for energy use and its associated costs, and uses both ET and soil moisture measurements to enhance the accuracy of the irrigation schedules. IEM was developed specifically for implementing Deficit Irrigation and therefore includes analyses that go beyond the requirements of conventional irrigation scheduling. The third section describes Irrigation Management Online (IMO), a web application for optimum irrigation management. This system uses IEM to generate and deliver irrigation scheduling recommendations. IMO has been developed specifically to support irrigation management when either water supplies or delivery system capacities are limited. To mitigate the complexities of irrigation constraints the system has been designed so that the irrigation manager is an integral part of the irrigation optimization procedure. The final section outlines some of the key challenges that the next generation of schedulers must overcome in order to meet the needs of agricultural irrigation in an increasingly water short future. In addition, this section will discuss how irrigation advisory programs will need to operate differently in terms of what they do and how they do it. Title: Optimal irrigation management : a framework, model, and application for optimizing irrigation when supplies are limited Author: Hillyer, Charles C. (Charles Carter) Many regions in North America are experiencing water shortages, and these conditions are expected to worsen. The next generation of irrigation scheduling applications must therefore be capable of providing operational advice in support of deficit irrigation strategies. However, the theoretical, technical, and practical challenges associated with deficit irrigation scheduling are far more complex than conventional (full) irrigation. This dissertation presents three distinct systems for addressing the analytical challenges of deficit irrigation management. The first section of the dissertation presents a simulation framework for agro-ecological simulation. The objective was to develop a method to enable the assembly of simulation models from previously and independently developed component models. Based on a requirements analysis of existing simulation models we developed the ModCom simulation framework. ModCom provides a set of interface specifications that describe components in a simulation. ModCom also provides implementations of the core simulation services. The framework interfaces use well-defined binary standards and allows developers to implement the interfaces using a broad range of computer languages. The Second section describes the Irrigation Efficiency Model (IEM). IEM explicitly analyzes irrigation efficiency, accounts for spatial variability of soil properties and irrigation uniformity, performs simultaneous scheduling for all fields in the farm, accounts for energy use and its associated costs, and uses both ET and soil moisture measurements to enhance the accuracy of the irrigation schedules. IEM was developed specifically for implementing Deficit Irrigation and therefore includes analyses that go beyond the requirements of conventional irrigation scheduling. The third section describes Irrigation Management Online (IMO), a web application for optimum irrigation management. This system uses IEM to generate and deliver irrigation scheduling recommendations. IMO has been developed specifically to support irrigation management when either water supplies or delivery system capacities are limited. To mitigate the complexities of irrigation constraints the system has been designed so that the irrigation manager is an integral part of the irrigation optimization procedure. The final section outlines some of the key challenges that the next generation of schedulers must overcome in order to meet the needs of agricultural irrigation in an increasingly water short future. In addition, this section will discuss how irrigation advisory programs will need to operate differently in terms of what they do and how they do it. Close

• 2. [Article] Characterizing hydraulics and water distribution of furrow irrigation in northeast Malheur County

  Furrow irrigation is the dominant practice for irrigating row crops in the western Treasure Valley region near Ontario, Oregon. Though improvements have been made in management practices over the years, ...

  Citation × Citation Citation Abstract Copy Title: Characterizing hydraulics and water distribution of furrow irrigation in northeast Malheur County Author: Mittelstadt, Robert Furrow irrigation is the dominant practice for irrigating row crops in the western Treasure Valley region near Ontario, Oregon. Though improvements have been made in management practices over the years, excessive runoff and deep percolation are still important problems contributing to surface water and groundwater degradation. Field observations were made during two growing seasons to establish a data base from which the hydraulic surface irrigation model, SRFR (SRFR, a computer program for simulating flow in surface irrigation, developed at the U.S. Water Conservation Laboratory in Phoenix, Arizona (Strelkoff, 1991)), could be calibrated. SRFR is a numerical model, based on the principles of open channel hydraulics coupled with an empirical relationship characterizing furrow intake. SRFR is an analytical tool, with which the user supplies the physical parameters (such as furrow shape and furrow intake) and also the management variables (inflow rate and duration of inflow), and a simulation is conducted based on these conditions. Therefore, this model is a tool which provides insight into furrow irrigation processes. More specifically, SRFR can help answer such questions as which factors at the time of the irrigation are most important in determining irrigation performance. Once calibrated for a given set of conditions, various management strategies may be evaluated as to their relative effectiveness. These strategies may include, but are not limited to, cut-back irrigation, surge irrigation, alternating furrow irrigation, and laser-leveling of the field. A broad data-base is necessary for model calibration and to develop an understanding of it's limitations. Measurements of furrow intake, stream advance times, inflow and outflow, hydraulic roughness and furrow shape were obtained from several sites and irrigation events. These sites represent several crops, field lengths, field slopes, and soil textures. Using these data, a model calibration procedure was developed which matched irrigation inflow and outflow volumes and stream advance times for a given irrigation event. The calibration procedure is used to help identify those model input parameters that best describe a given irrigation event. This thesis is to provide a broad understanding of furrow irrigation systems in northeast Malheur County, recommended hydraulic parameters for use with SRFR, and the practical limitations of such hydraulic irrigation models. Irrigation performance is largely determined by the intake characteristics of the soil at the time of irrigation. Field conditions vary greatly depending on the crop, soil moisture, number of irrigations, tractor traffic, field slope, furrow shape and field history. The grower has control over only two variables which determine irrigation performance: inflow rate and duration. A difference in intake and irrigation performance was found to exist between non-wheel and wheel traffic furrows. These differences became less noticeable late in the season. Straw mulching greatly increases the furrow hydraulic roughness and therefore increases stream wetted perimeter and advance time. Vegetative interference from crops such as potato and sugar beets increase furrow hydraulic roughness late in the season. Initially, furrow shape depends on the crop and which cultivating implement is used. Furrow shape may evolve during the growing season depending on field slope, flow velocities, crop stand and the presence of crop residues and straw mulch. Title: Characterizing hydraulics and water distribution of furrow irrigation in northeast Malheur County Author: Mittelstadt, Robert Furrow irrigation is the dominant practice for irrigating row crops in the western Treasure Valley region near Ontario, Oregon. Though improvements have been made in management practices over the years, excessive runoff and deep percolation are still important problems contributing to surface water and groundwater degradation. Field observations were made during two growing seasons to establish a data base from which the hydraulic surface irrigation model, SRFR (SRFR, a computer program for simulating flow in surface irrigation, developed at the U.S. Water Conservation Laboratory in Phoenix, Arizona (Strelkoff, 1991)), could be calibrated. SRFR is a numerical model, based on the principles of open channel hydraulics coupled with an empirical relationship characterizing furrow intake. SRFR is an analytical tool, with which the user supplies the physical parameters (such as furrow shape and furrow intake) and also the management variables (inflow rate and duration of inflow), and a simulation is conducted based on these conditions. Therefore, this model is a tool which provides insight into furrow irrigation processes. More specifically, SRFR can help answer such questions as which factors at the time of the irrigation are most important in determining irrigation performance. Once calibrated for a given set of conditions, various management strategies may be evaluated as to their relative effectiveness. These strategies may include, but are not limited to, cut-back irrigation, surge irrigation, alternating furrow irrigation, and laser-leveling of the field. A broad data-base is necessary for model calibration and to develop an understanding of it's limitations. Measurements of furrow intake, stream advance times, inflow and outflow, hydraulic roughness and furrow shape were obtained from several sites and irrigation events. These sites represent several crops, field lengths, field slopes, and soil textures. Using these data, a model calibration procedure was developed which matched irrigation inflow and outflow volumes and stream advance times for a given irrigation event. The calibration procedure is used to help identify those model input parameters that best describe a given irrigation event. This thesis is to provide a broad understanding of furrow irrigation systems in northeast Malheur County, recommended hydraulic parameters for use with SRFR, and the practical limitations of such hydraulic irrigation models. Irrigation performance is largely determined by the intake characteristics of the soil at the time of irrigation. Field conditions vary greatly depending on the crop, soil moisture, number of irrigations, tractor traffic, field slope, furrow shape and field history. The grower has control over only two variables which determine irrigation performance: inflow rate and duration. A difference in intake and irrigation performance was found to exist between non-wheel and wheel traffic furrows. These differences became less noticeable late in the season. Straw mulching greatly increases the furrow hydraulic roughness and therefore increases stream wetted perimeter and advance time. Vegetative interference from crops such as potato and sugar beets increase furrow hydraulic roughness late in the season. Initially, furrow shape depends on the crop and which cultivating implement is used. Furrow shape may evolve during the growing season depending on field slope, flow velocities, crop stand and the presence of crop residues and straw mulch. Close

• 3. [Article] A computer model to simulate farm irrigation system energy requirements

  The development of the energy crisis has caused the use of depletable energy resources to be monitored quite closely in the United States. Within the agricultural sector, irrigation is a large user of ...

  Citation × Citation Citation Abstract Copy Title: A computer model to simulate farm irrigation system energy requirements Author: Kizer, Michael A. The development of the energy crisis has caused the use of depletable energy resources to be monitored quite closely in the United States. Within the agricultural sector, irrigation is a large user of energy, with the potential of using many times more energy than all other agricultural field operations. A better understanding of how energy is used by different irrigation systems could facilitate more efficient use of energy by one of the largest energy consumers in agriculture. This thesis attempts to realistically evaluate the total amount of non-renewable energy resources consumed in the irrigation process. Five portable and permanent sprinkler system types, plus trickle and gravity irrigation systems were studied. An evaluation of the energy required to manufacture the equipment, install it in the field, operate it, and transport it for an entire irrigation season was made. This evaluation was carried out in a variety of operating situations, with varying acreages, consumptive use rates, and total irrigation requirements. The paper begins by giving some background information about agriculture and irrigation as consumers of energy. A review of some of the research previously done which relates to energy use in irrigation is given. The evaluation of energy use by irrigation systems presented in this thesis were made with the use of a simulation model which was developed on the Oregon State University OS-3 Computer System. The model predicts energy requirements of an irrigation system by evaluating pumping energy requirements with basic hydraulic equations, the manufacturing energy requirements by calculating the required amounts of basic materials making up the system and the energy of manufacture of those basic materials. The energy for installation and the energy for transportation were evaluated by simulating methods of operation and management used in Oregon. The input parameters used in the modeling process. reproduce as closely as possible operating conditions encountered in Oregon. System types, component depreciation life, irrigation efficiencies and the range of irrigation requirements are ones that could typically be found in Oregon. For the situations considered, it was concluded that gravity irrigation required much less energy than other system types. The energy requirement for drip systems was about midway between the energy requirement for gravity systems and for sprinkler systems for most cases considered. The relative order of energy requirements for the various sprinkler systems was dependent upon the operating conditions considered. Title: A computer model to simulate farm irrigation system energy requirements Author: Kizer, Michael A. The development of the energy crisis has caused the use of depletable energy resources to be monitored quite closely in the United States. Within the agricultural sector, irrigation is a large user of energy, with the potential of using many times more energy than all other agricultural field operations. A better understanding of how energy is used by different irrigation systems could facilitate more efficient use of energy by one of the largest energy consumers in agriculture. This thesis attempts to realistically evaluate the total amount of non-renewable energy resources consumed in the irrigation process. Five portable and permanent sprinkler system types, plus trickle and gravity irrigation systems were studied. An evaluation of the energy required to manufacture the equipment, install it in the field, operate it, and transport it for an entire irrigation season was made. This evaluation was carried out in a variety of operating situations, with varying acreages, consumptive use rates, and total irrigation requirements. The paper begins by giving some background information about agriculture and irrigation as consumers of energy. A review of some of the research previously done which relates to energy use in irrigation is given. The evaluation of energy use by irrigation systems presented in this thesis were made with the use of a simulation model which was developed on the Oregon State University OS-3 Computer System. The model predicts energy requirements of an irrigation system by evaluating pumping energy requirements with basic hydraulic equations, the manufacturing energy requirements by calculating the required amounts of basic materials making up the system and the energy of manufacture of those basic materials. The energy for installation and the energy for transportation were evaluated by simulating methods of operation and management used in Oregon. The input parameters used in the modeling process. reproduce as closely as possible operating conditions encountered in Oregon. System types, component depreciation life, irrigation efficiencies and the range of irrigation requirements are ones that could typically be found in Oregon. For the situations considered, it was concluded that gravity irrigation required much less energy than other system types. The energy requirement for drip systems was about midway between the energy requirement for gravity systems and for sprinkler systems for most cases considered. The relative order of energy requirements for the various sprinkler systems was dependent upon the operating conditions considered. Close

• 4. [Article] Basin-wide distributed modeling of hydrologic responses to irrigation management in the Wood River Basin, Klamath County, OR

  The Wood River Basin lies upstream of Upper Klamath Lake, the main reservoir of the USBR Klamath Irrigation Project that provides irrigation water to 210,000 acres of downstream land. Water allocation ...

  Citation × Citation Citation Abstract Copy Title: Basin-wide distributed modeling of hydrologic responses to irrigation management in the Wood River Basin, Klamath County, OR Author: Owens, Joshua M. The Wood River Basin lies upstream of Upper Klamath Lake, the main reservoir of the USBR Klamath Irrigation Project that provides irrigation water to 210,000 acres of downstream land. Water allocation became a contentious issue in 2001 when drought led to curtailment of irrigation deliveries to the Klamath Irrigation Project in order to maintain minimum lake levels and river flows for endangered species. After lengthy negotiations the Klamath Basin Restoration Agreement was signed in February 2010, and calls for flow increases of 30,000 ac-ft/yr into Upper Klamath Lake from voluntary upstream sources. The Wood River Basin is a potential source of this water, but poorly understood hydrology makes estimates of water gains in response to conservation strategies uncertain. To better understand the hydrology of the Wood River Basin a fully distributed, physically based model was set up using the MIKE SHE hydrology model and MIKE 11 hydraulic model by DHI, Inc. The model was developed by recreating the actual management of the basin from 2002 to 2009, a period when tracts of land in the basin were enrolled in land idling programs for water conservation. Calibration and validation was evaluated against shallow groundwater observations. Overall the model described the average conditions of the basin well. Locations that were simulated inaccurately were limited to those in close proximity to the model boundary or to the Wood River, the result of using average values to describe these heterogeneous features. The model was used to simulate two end-member scenarios to determine the limits of water conservation strategies, basin-wide full irrigation and non-irrigation. Two reduced irrigation scenarios were also simulated, the first reduced the irrigation season to June and July, the second eliminated every other irrigation application. The simulation that recreated the actual management showed that non-irrigated tracts did not substantially reduce the consumptive use because water from the surrounding irrigated tracts was able to flow in via the shallow aquifer and provide sub-irrigation. For the full irrigation scenario the average annual consumptive use was 126,000 ac-ft/yr. For the non-irrigated scenario it was 96,000 ac-ft/yr, a reduction of 24%. For the two reduced irrigation scenarios the consumptive use was decreased by 14% and 12%. When compared to the irrigated scenario the total increase of flow to Upper Klamath Lake during the growing season was 60,000 ac-ft/yr for the non-irrigated scenario; and 36,000 ac-ft/yr and 31,000 ac-ft/yr for the two reduced irrigation scenarios respectively. Irrigation in the basin was found to transfer stream flow from the summer time to the winter time due to saturated winter conditions from late season irrigations resulting in increased runoff. There is potential for water conservation strategies in the Wood River Basin to substantially increase water flow into Upper Klamath Lake, but these strategies would have to be implemented extensively throughout the basin to reduce sub-irrigation. Title: Basin-wide distributed modeling of hydrologic responses to irrigation management in the Wood River Basin, Klamath County, OR Author: Owens, Joshua M. The Wood River Basin lies upstream of Upper Klamath Lake, the main reservoir of the USBR Klamath Irrigation Project that provides irrigation water to 210,000 acres of downstream land. Water allocation became a contentious issue in 2001 when drought led to curtailment of irrigation deliveries to the Klamath Irrigation Project in order to maintain minimum lake levels and river flows for endangered species. After lengthy negotiations the Klamath Basin Restoration Agreement was signed in February 2010, and calls for flow increases of 30,000 ac-ft/yr into Upper Klamath Lake from voluntary upstream sources. The Wood River Basin is a potential source of this water, but poorly understood hydrology makes estimates of water gains in response to conservation strategies uncertain. To better understand the hydrology of the Wood River Basin a fully distributed, physically based model was set up using the MIKE SHE hydrology model and MIKE 11 hydraulic model by DHI, Inc. The model was developed by recreating the actual management of the basin from 2002 to 2009, a period when tracts of land in the basin were enrolled in land idling programs for water conservation. Calibration and validation was evaluated against shallow groundwater observations. Overall the model described the average conditions of the basin well. Locations that were simulated inaccurately were limited to those in close proximity to the model boundary or to the Wood River, the result of using average values to describe these heterogeneous features. The model was used to simulate two end-member scenarios to determine the limits of water conservation strategies, basin-wide full irrigation and non-irrigation. Two reduced irrigation scenarios were also simulated, the first reduced the irrigation season to June and July, the second eliminated every other irrigation application. The simulation that recreated the actual management showed that non-irrigated tracts did not substantially reduce the consumptive use because water from the surrounding irrigated tracts was able to flow in via the shallow aquifer and provide sub-irrigation. For the full irrigation scenario the average annual consumptive use was 126,000 ac-ft/yr. For the non-irrigated scenario it was 96,000 ac-ft/yr, a reduction of 24%. For the two reduced irrigation scenarios the consumptive use was decreased by 14% and 12%. When compared to the irrigated scenario the total increase of flow to Upper Klamath Lake during the growing season was 60,000 ac-ft/yr for the non-irrigated scenario; and 36,000 ac-ft/yr and 31,000 ac-ft/yr for the two reduced irrigation scenarios respectively. Irrigation in the basin was found to transfer stream flow from the summer time to the winter time due to saturated winter conditions from late season irrigations resulting in increased runoff. There is potential for water conservation strategies in the Wood River Basin to substantially increase water flow into Upper Klamath Lake, but these strategies would have to be implemented extensively throughout the basin to reduce sub-irrigation. Close

• 5. [Article] Irrigation decision survey data for the Willamette Water 2100 project

  [suggested citation: "Jaeger, William K. (2016): Irrigation decision survey data for the Willamette Water 2100 project. OSU Libraries. Dataset. http://dx.doi.org/10.7267/N9H12ZXK"]

  Citation × Citation Citation Abstract Copy Title: Irrigation decision survey data for the Willamette Water 2100 project Author: Jaeger, William K. [suggested citation: "Jaeger, William K. (2016): Irrigation decision survey data for the Willamette Water 2100 project. OSU Libraries. Dataset. http://dx.doi.org/10.7267/N9H12ZXK"] Title: Irrigation decision survey data for the Willamette Water 2100 project Author: Jaeger, William K. [suggested citation: "Jaeger, William K. (2016): Irrigation decision survey data for the Willamette Water 2100 project. OSU Libraries. Dataset. http://dx.doi.org/10.7267/N9H12ZXK"] Close

• 6. [Article] Spring irrigation management of perennial ryegrass (Lolium perenne L.) seed production

  Introduction of later maturing cultivars of perennial ryegrass (Lolium perenne L.) places more seed production fields in a period of drought common to Oregon during vital stages of reproductive development. ...

  Citation × Citation Citation Abstract Copy Title: Spring irrigation management of perennial ryegrass (Lolium perenne L.) seed production Author: King, Craig Millhouser Introduction of later maturing cultivars of perennial ryegrass (Lolium perenne L.) places more seed production fields in a period of drought common to Oregon during vital stages of reproductive development. During these stages, the final yield of the crop is largely determined by the number of seeds set, and the development of individual seed weight. There is belief that water deficit during these periods may drastically reduce yield, which could be eliminated with properly timed spring irrigation. Therefore, this study was undertaken to (i) determine crop water use and water use efficiency of both irrigated and non-irrigated perennial ryegrass cultivars, (ii) observe any water use differences as a result of cultivar differences in perennial ryegrass, (iii) compare seed yield and seed yield components of different cultivars within irrigated and non-irrigated treatments, and (iv) determine appropriate timing and amount of irrigation to apply if it is revealed that irrigation enhances yield. A linear irrigation system was used to apply irrigation to six cultivars of perennial ryegrass in the crop years 2003 and 2004. In 2003 from 1 March to 25 July, 285 mm of water was consumed by non-irrigated plants, 365 mm when soil profile was filled once prior to peak anthesis, and 388 mm when soil moisture was maintained within 50 mm of field capacity to peak anthesis. In 2004 from 1 March to 8 July, nonirrigated plants consumed 279 mm of water, 353 mm from treatment to fill soil profile once, and 482 mm from treatment that maintained soil moisture up to peak anthesis. No statistical difference was observed in water use efficiency between treatments in 2003. In 2004 an interaction was observed between cultivars and irrigation, thus cultivars responded differently to irrigation. Contrasts revealed that cultivars responded differently with respect to water use efficiency. In 2003, irrigation to maintain soil moisture resulted in a 27% increase in yield, 18% due to an increase in seed number, and 8% due to an increase in seed weight. Irrigation to fill profile once resulted in a 21% increase in yield, 14% due to an increase in seed number, and 6% due to an increase in seed weight. In 2004 a cultivar by irrigation interaction was observed for total yield, seed weight, and seed number. Seed yield was increased by irrigation in all cultivars. In 2003, irrigation to maintain soil moisture began 3 June and corresponded with the beginning of anthesis, and proceeded to peak anthesis, 11 June. No rainfall was received during this period, or the period of seed fill which followed. In 2004 irrigation to maintain soil moisture began 29 April, and continued to peak anthesis, 4 June. Irrigation to fill profile once occurred between 3 June and 7 June in 2003, and between 31 May and 4 June in 2004. In 2004 significant rainfall occurred after peak anthesis during the period of seed fill. Data from both years suggest that irrigation to alleviate water deficit from the onset of anthesis through peak anthesis provides the plant with sufficient water to increase individual seed weight and seed set, thus improving overall yield. Title: Spring irrigation management of perennial ryegrass (Lolium perenne L.) seed production Author: King, Craig Millhouser Introduction of later maturing cultivars of perennial ryegrass (Lolium perenne L.) places more seed production fields in a period of drought common to Oregon during vital stages of reproductive development. During these stages, the final yield of the crop is largely determined by the number of seeds set, and the development of individual seed weight. There is belief that water deficit during these periods may drastically reduce yield, which could be eliminated with properly timed spring irrigation. Therefore, this study was undertaken to (i) determine crop water use and water use efficiency of both irrigated and non-irrigated perennial ryegrass cultivars, (ii) observe any water use differences as a result of cultivar differences in perennial ryegrass, (iii) compare seed yield and seed yield components of different cultivars within irrigated and non-irrigated treatments, and (iv) determine appropriate timing and amount of irrigation to apply if it is revealed that irrigation enhances yield. A linear irrigation system was used to apply irrigation to six cultivars of perennial ryegrass in the crop years 2003 and 2004. In 2003 from 1 March to 25 July, 285 mm of water was consumed by non-irrigated plants, 365 mm when soil profile was filled once prior to peak anthesis, and 388 mm when soil moisture was maintained within 50 mm of field capacity to peak anthesis. In 2004 from 1 March to 8 July, nonirrigated plants consumed 279 mm of water, 353 mm from treatment to fill soil profile once, and 482 mm from treatment that maintained soil moisture up to peak anthesis. No statistical difference was observed in water use efficiency between treatments in 2003. In 2004 an interaction was observed between cultivars and irrigation, thus cultivars responded differently to irrigation. Contrasts revealed that cultivars responded differently with respect to water use efficiency. In 2003, irrigation to maintain soil moisture resulted in a 27% increase in yield, 18% due to an increase in seed number, and 8% due to an increase in seed weight. Irrigation to fill profile once resulted in a 21% increase in yield, 14% due to an increase in seed number, and 6% due to an increase in seed weight. In 2004 a cultivar by irrigation interaction was observed for total yield, seed weight, and seed number. Seed yield was increased by irrigation in all cultivars. In 2003, irrigation to maintain soil moisture began 3 June and corresponded with the beginning of anthesis, and proceeded to peak anthesis, 11 June. No rainfall was received during this period, or the period of seed fill which followed. In 2004 irrigation to maintain soil moisture began 29 April, and continued to peak anthesis, 4 June. Irrigation to fill profile once occurred between 3 June and 7 June in 2003, and between 31 May and 4 June in 2004. In 2004 significant rainfall occurred after peak anthesis during the period of seed fill. Data from both years suggest that irrigation to alleviate water deficit from the onset of anthesis through peak anthesis provides the plant with sufficient water to increase individual seed weight and seed set, thus improving overall yield. Close

• 7. [Article] Drip vs. furrow irrigation in the delivery of Escherichia coli to onions

  This is the publisher’s final pdf. The published article is copyrighted by the American Society of Agricultural and Biological Engineers and can be found at: https://elibrary.asabe.org/toc_landing.asp?...

  Citation × Citation Citation Abstract Copy Title: Drip vs. furrow irrigation in the delivery of Escherichia coli to onions Author: Shock, C. C., Kreeft, H., Roncarati, R. A., Reitz, S. R., Klauzer, J. C., Shock, B. M. This is the publisher’s final pdf. The published article is copyrighted by the American Society of Agricultural and Biological Engineers and can be found at: https://elibrary.asabe.org/toc_landing.asp?conf=aeaj Title: Drip vs. furrow irrigation in the delivery of Escherichia coli to onions Author: Shock, C. C., Kreeft, H., Roncarati, R. A., Reitz, S. R., Klauzer, J. C., Shock, B. M. This is the publisher’s final pdf. The published article is copyrighted by the American Society of Agricultural and Biological Engineers and can be found at: https://elibrary.asabe.org/toc_landing.asp?conf=aeaj Close

• 8. [Article] Effects of irrigation frequency on yields of winter wheat

  Deliberately underirrigating a crop may yield economic benefits. The optimal use of water by an irrigator should be achieved under a deficit irrigation regime. It is important to know how water deficits ...

  Citation × Citation Citation Abstract Copy Title: Effects of irrigation frequency on yields of winter wheat Author: Nakamura, Brian Clifford Deliberately underirrigating a crop may yield economic benefits. The optimal use of water by an irrigator should be achieved under a deficit irrigation regime. It is important to know how water deficits affect yields and the interaction of the deficits with the scheduling of irrigations. A field experiment was conducted during the 1981 irrigation season to investigate the effects of high and low frequency deficit irrigation on yields of winter wheat. Yield and water use data were used to construct three production functions. The relationship between the level of water use and the resulting yield were determined for three irrigation frequency regimes. Field plots under daily (high frequency), weekly (normal frequency), and stress (reduced frequency) regimes were included in the field experiment as well as two dryland production plots. The relationships derived from this project were characterized by a large degree of scatter in the results. Highly favorable weather conditions offset the effects of irrigation deficits on plant yields throughout the irrigation season. At this time, a second year of data is in the process of compilation. The results of a regression analysis showed no statistically significant difference in the water use-yield relationships of the three irrigation frequency regimes. The effect of frequency did not lead to any readily apparent differences in the three production functions. The efficiency of water use of the different irrigation frequencies increases with decreasing amount of applied water for the 1981 crop year. The most efficient treatment, i.e., least water use per unit of yield, was the pre-plant irrigated, dryfarmed plots. The density of the wheat, a measure of crop quality also increased with decreased water use in this experiment. The optimal irrigation treatment (measured by production and quality) was the two-week frequency set. Title: Effects of irrigation frequency on yields of winter wheat Author: Nakamura, Brian Clifford Deliberately underirrigating a crop may yield economic benefits. The optimal use of water by an irrigator should be achieved under a deficit irrigation regime. It is important to know how water deficits affect yields and the interaction of the deficits with the scheduling of irrigations. A field experiment was conducted during the 1981 irrigation season to investigate the effects of high and low frequency deficit irrigation on yields of winter wheat. Yield and water use data were used to construct three production functions. The relationship between the level of water use and the resulting yield were determined for three irrigation frequency regimes. Field plots under daily (high frequency), weekly (normal frequency), and stress (reduced frequency) regimes were included in the field experiment as well as two dryland production plots. The relationships derived from this project were characterized by a large degree of scatter in the results. Highly favorable weather conditions offset the effects of irrigation deficits on plant yields throughout the irrigation season. At this time, a second year of data is in the process of compilation. The results of a regression analysis showed no statistically significant difference in the water use-yield relationships of the three irrigation frequency regimes. The effect of frequency did not lead to any readily apparent differences in the three production functions. The efficiency of water use of the different irrigation frequencies increases with decreasing amount of applied water for the 1981 crop year. The most efficient treatment, i.e., least water use per unit of yield, was the pre-plant irrigated, dryfarmed plots. The density of the wheat, a measure of crop quality also increased with decreased water use in this experiment. The optimal irrigation treatment (measured by production and quality) was the two-week frequency set. Close

• 9. [Article] Towards autonomous irrigation : comparison of two moisture sensing technologies, irrigation distribution analysis, and wireless network performance at an ornamental container nursery

  As ornamental container nurseries face diminishing water allocations, many are looking to automated irrigation solutions to increase their water application efficiency. This thesis presents the findings ...

  Citation × Citation Citation Abstract Copy Title: Towards autonomous irrigation : comparison of two moisture sensing technologies, irrigation distribution analysis, and wireless network performance at an ornamental container nursery Author: Bailey, Daniel R. (Daniel Roger) As ornamental container nurseries face diminishing water allocations, many are looking to automated irrigation solutions to increase their water application efficiency. This thesis presents the findings of a study conducted at a commercial container nursery to determine 1) whether a capacitance or load cell sensor was better suited for monitoring volumetric water content in the substrate; 2) if the actual irrigation distribution conformed to the expected pattern, how uniform were the weights of plants, and how these combined with plant canopy affected the leaching fraction; and 3) the reliability of the wireless network used to transmit the data to a central database. It was found that 1) the load cells outperformed the capacitance-based sensors because the load cells took an integrated measure; 2) the actual irrigation pattern followed the expected pattern, the variation of irrigation sections were low (C.V. = 0.06) and similar (C.V. ranging from 0.029 to 0.12), and unpruned plant canopies produced greater leaching fraction than pruned canopies (P < 0.18); and 3) wireless network transmission reliability was low (75.2%), suggesting that the system was not suitable for real-time irrigation control, but was sufficient for calculating irrigation length and monitoring net effective irrigation application and evapotranspirative consumption. Title: Towards autonomous irrigation : comparison of two moisture sensing technologies, irrigation distribution analysis, and wireless network performance at an ornamental container nursery Author: Bailey, Daniel R. (Daniel Roger) As ornamental container nurseries face diminishing water allocations, many are looking to automated irrigation solutions to increase their water application efficiency. This thesis presents the findings of a study conducted at a commercial container nursery to determine 1) whether a capacitance or load cell sensor was better suited for monitoring volumetric water content in the substrate; 2) if the actual irrigation distribution conformed to the expected pattern, how uniform were the weights of plants, and how these combined with plant canopy affected the leaching fraction; and 3) the reliability of the wireless network used to transmit the data to a central database. It was found that 1) the load cells outperformed the capacitance-based sensors because the load cells took an integrated measure; 2) the actual irrigation pattern followed the expected pattern, the variation of irrigation sections were low (C.V. = 0.06) and similar (C.V. ranging from 0.029 to 0.12), and unpruned plant canopies produced greater leaching fraction than pruned canopies (P < 0.18); and 3) wireless network transmission reliability was low (75.2%), suggesting that the system was not suitable for real-time irrigation control, but was sufficient for calculating irrigation length and monitoring net effective irrigation application and evapotranspirative consumption. Close

• 10. [Article] The effects of farm and operator characteristics, knowledge, and attitudes on farm-level improvements in irrigation efficiency in the central Willamette Valley

  A study was conducted using data collected from a sample of mint and vegetable farmers in the Willamette Valley of Oregon. The study identifies the influence of demographic differences, economic factors ...

  Citation × Citation Citation Abstract Copy Title: The effects of farm and operator characteristics, knowledge, and attitudes on farm-level improvements in irrigation efficiency in the central Willamette Valley Author: Stoff, Mary Cora A study was conducted using data collected from a sample of mint and vegetable farmers in the Willamette Valley of Oregon. The study identifies the influence of demographic differences, economic factors and irrigator attitudes on irrigation efficiency. Only two of the 19 characteristics theorized to influence irrigation efficiency proved to be statistically significant in both of two models. These significant variables, crop type (CROP), soil type (SOIL) suggest that a farmer's irrigation efficiency is unaffected by personal characteristics or attitudes. According to these results, the irrigator apparently applied the water that she deemed necessary, a decision based solely on the needs of the crop and the water-holding capacity of the soil. Title: The effects of farm and operator characteristics, knowledge, and attitudes on farm-level improvements in irrigation efficiency in the central Willamette Valley Author: Stoff, Mary Cora A study was conducted using data collected from a sample of mint and vegetable farmers in the Willamette Valley of Oregon. The study identifies the influence of demographic differences, economic factors and irrigator attitudes on irrigation efficiency. Only two of the 19 characteristics theorized to influence irrigation efficiency proved to be statistically significant in both of two models. These significant variables, crop type (CROP), soil type (SOIL) suggest that a farmer's irrigation efficiency is unaffected by personal characteristics or attitudes. According to these results, the irrigator apparently applied the water that she deemed necessary, a decision based solely on the needs of the crop and the water-holding capacity of the soil. Close