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Precision Drought Stress In Orchards: Rootstock Evaluation, Trunk Hydration And Canopy Temperature, Lance V. Scott 2017 Utah State University

Precision Drought Stress In Orchards: Rootstock Evaluation, Trunk Hydration And Canopy Temperature, Lance V. Scott

All Graduate Theses and Dissertations

In many areas, over half of all diverted water is used for irrigation. Tree fruit crops use a lot of water, but water productivity can be increased using properly-timed precision water stress. In addition to water conservation, increases in water productivity arise from better fruit quality, increased storage life and reductions in pruning and maintenance. One major hurdle to applying precision water stress in orchards is the lack of a reliable, automated method of determining tree water status. However, the influence of physiological characteristics such as rootstock vigor on water productivity are also important. Selecting the most appropriate rootstocks and ...


Seasonal And Rotational Influences On Corn Nitrogen Fertilization In Southwest Iowa, John Sawyer, Daniel Barker 2017 Iowa State University

Seasonal And Rotational Influences On Corn Nitrogen Fertilization In Southwest Iowa, John Sawyer, Daniel Barker

John E. Sawyer

This project was designed to study the nitrogen (N) fertilization needs in continuous corn (CC) and corn rotated with soybean (CS) as influenced by location and climate. Multiple rates of fertilizer N were spring applied, with the intent to measure yield response to N within each rotation on a yearly basis for multiple years at multiple sites across Iowa. This will allow determination of N requirements for each rotation, differences that exist between the two rotations, responses to applied N across different soils and climatic conditions, and evaluation of tools used to adjust N application.


Corn Yield Response To Nitrogen Fertilizer Application Timing In Northeast Iowa, John Lundvall, Dan Barker, John Sawyer 2017 Iowa State University

Corn Yield Response To Nitrogen Fertilizer Application Timing In Northeast Iowa, John Lundvall, Dan Barker, John Sawyer

John E. Sawyer

The objective of this project was to measure corn yield response to fertilizer nitrogen (N) application timing (spring pre-plant or at-planting vs. split/side-dress) across multiple N rates (0 to 250 lb total-N/acre). Results were determined through fitting yield response to N-rate regression equations and calculation of economic optimum nitrogen rate (EONR) based on a 0.10 N fertilizer price-to-corn price ratio.


Corn Yield Response To Nitrogen Fertilizer Application Timing In Southwest Iowa, John Lundvall, Dan Barker, John Sawyer 2017 Iowa State University

Corn Yield Response To Nitrogen Fertilizer Application Timing In Southwest Iowa, John Lundvall, Dan Barker, John Sawyer

John E. Sawyer

The objective of this project was to measure corn yield response to fertilizer nitrogen (N) application timing (spring pre-plant or at-planting vs. split/side-dress) across multiple N rates (0 to 250 lb total-N/acre). Results were determined through fitting yield response to N-rate regression equations and calculation of economic optimum nitrogen rate (EONR) based on a 0.10 N fertilizer price-to-corn price ratio.


Enhancing Corn Yield In A Winter Cereal Rye Cover Crop System In Northeast Iowa, John Lundvall, Swetabh Patel, John Sawyer 2017 Iowa State University

Enhancing Corn Yield In A Winter Cereal Rye Cover Crop System In Northeast Iowa, John Lundvall, Swetabh Patel, John Sawyer

John E. Sawyer

Water quality impairment related to nitrogen (N) is a concern in Iowa, including meeting nitrate (NO3) drinking water standards and reducing the amount of N lost to the Gulf of Mexico. The Iowa Nutrient Reduction Strategy science assessment identified a rye cover crop as an important in-field management practice for reducing N and phosphorus (P) loss from fields (31% NO3-N and 29% P), and for reducing soil erosion. However, the science assessment identified a corn yield reduction of 6 percent when grown following a rye cover crop. Lower corn yield with use of a cover crop is unacceptable to farmers ...


Enhancing Corn Yield In A Winter Cereal Rye Cover Crop System In Southwest Iowa, John Lundvall, Swetabh Patel, John Sawyer 2017 Iowa State University

Enhancing Corn Yield In A Winter Cereal Rye Cover Crop System In Southwest Iowa, John Lundvall, Swetabh Patel, John Sawyer

John E. Sawyer

Water quality impairment related to nitrogen (N) is a concern in Iowa, including meeting nitrate (NO3) drinking water standards and reducing the amount of N lost to the Gulf of Mexico. The Iowa Nutrient Reduction Strategy science assessment identified a rye cover crop as an important in-field management practice for reducing N and phosphorus (P) loss from fields (31% NO3-N and 29% P), and for reducing soil erosion. However, the science assessment identified a corn yield reduction of 6 percent when grown following a rye cover crop. Lower corn yield with use of a cover crop is unacceptable to farmers ...


Impact Of 4r Management On Crop Production And Nitrate-Nitrogen Loss In Tile Drainage, Matthew Helmers, John Sawyer, Carl Pederson 2017 Iowa State University

Impact Of 4r Management On Crop Production And Nitrate-Nitrogen Loss In Tile Drainage, Matthew Helmers, John Sawyer, Carl Pederson

John E. Sawyer

Corn Belt corn and soybean producers are increasingly challenged to maximize crop production while addressing the contributions farm practices make to Gulf hypoxia. Based on the need for nitrate-N reductions in surface water systems to meet water quality goals, new management practices are needed to reduce nitrate-N losses at minimal cost and maximum economic benefits. This three-year field research and demonstration project is evaluating various promising N management methods and technologies by documenting the nitrate-N export and crop yield from various systems.


Enhancing Corn Yield In A Winter Cereal Rye Cover Crop System In Southeast Iowa, John Lundvall, Swetabh Patel, John Sawyer 2017 Iowa State University

Enhancing Corn Yield In A Winter Cereal Rye Cover Crop System In Southeast Iowa, John Lundvall, Swetabh Patel, John Sawyer

John E. Sawyer

Water quality impairment related to nitrogen (N) is a concern in Iowa, including meeting nitrate (NO3) drinking water standards and reducing the amount of N lost to the Gulf of Mexico. The Iowa Nutrient Reduction Strategy science assessment identified a rye cover crop as an important in-field management practice for reducing N and phosphorus (P) loss from fields (31% NO3-N and 29% P), and for reducing soil erosion. However, the science assessment identified a corn yield reduction of 6 percent when grown following a rye cover crop. Lower corn yield with use of a cover crop is unacceptable to farmers ...


Seasonal And Rotational Influences On Corn Nitrogen Fertilization In Northeast Iowa, John Sawyer, Daniell Barker 2017 Iowa State University

Seasonal And Rotational Influences On Corn Nitrogen Fertilization In Northeast Iowa, John Sawyer, Daniell Barker

John E. Sawyer

This project was designed to study the N fertilization needs in continuous corn (CC) and corn rotated with soybean (CS) as influenced by location and climate. Multiple rates of fertilizer N were spring applied, with the intent to measure yield response to N within each rotation on a yearly basis for multiple years at multiple sites across Iowa. This will allow determination of N requirements for each rotation, differences that exist between the two rotations, responses to applied N across different soils and climatic conditions, and evaluation of tools used to adjust N application.


Enhancing Corn Yield In A Winter Cereal Rye Cover Crop System In Northwest Iowa, John Lundvall, Swetabh Patel, John Sawyer 2017 Iowa State University

Enhancing Corn Yield In A Winter Cereal Rye Cover Crop System In Northwest Iowa, John Lundvall, Swetabh Patel, John Sawyer

John E. Sawyer

Water quality impairment related to nitrogen (N) is a concern in Iowa, including meeting nitrate (NO3) drinking water standards and reducing the amount of N lost to the Gulf of Mexico. The Iowa Nutrient Reduction Strategy science assessment identified a rye cover crop as an important in-field management practice for reducing N and phosphorus (P) loss from fields (31% NO3-N and 29% P), and for reducing soil erosion. However, the science assessment identified a corn yield reduction of 6 percent when grown following a rye cover crop. Lower corn yield with use of a cover crop is unacceptable to farmers ...


Seasonal And Rotational Influences On Corn Nitrogen Fertilization In Northwest Iowa, John Sawyer, Daniel Barker 2017 Iowa State University

Seasonal And Rotational Influences On Corn Nitrogen Fertilization In Northwest Iowa, John Sawyer, Daniel Barker

John E. Sawyer

This project was designed to study the N fertilization needs in continuous corn (CC) and corn rotated with soybean (SC) as influenced by location and climate. Multiple rates of fertilizer N were spring applied, with the intent to measure yield response to N within each rotation on a yearly basis for multiple years at multiple sites across Iowa. This will allow determination of N requirements for each rotation, differences that exist between the two rotations, responses to applied N across different soils and climatic conditions, and evaluation of tools used to adjust N application.


Corn Yield Response To Nitrogen Fertilizer Application Timing In Southeast Iowa, John Lundvall, Dan Barker, John Sawyer 2017 Iowa State University

Corn Yield Response To Nitrogen Fertilizer Application Timing In Southeast Iowa, John Lundvall, Dan Barker, John Sawyer

John E. Sawyer

The objective of this project was to measure corn yield response to fertilizer nitrogen (N) application timing (spring pre-plant or at-planting vs. split/side-dress) across multiple N rates (0 to 250 lb total-N/acre). Results were determined through fitting yield response to N-rate regression equations and calculation of economic optimum nitrogen rate (EONR) based on a 0.10 N fertilizer price-to-corn price ratio.


Effect Of Drought On Resin Production In Woody Stems Of Rhus Ovata, Sydney T. Adams, Melody Young, Moriah Hall 2017 Pepperdine University

Effect Of Drought On Resin Production In Woody Stems Of Rhus Ovata, Sydney T. Adams, Melody Young, Moriah Hall

Seaver College Research And Scholarly Achievement Symposium

Resin production in stems of woody plants is generated from resin canal secretions and is thought to play a significant role in protection from fungal infection and spread. This may be one of several factors associated with fungal infection and fungal induced dieback in plants during severe water stress or drought. We set out to determine if reduction in resin production in a chaparral shrub, Sugar Bush (Rhus ovata), was associated with severe drought in southern California. We hypothesized that dehydrated R. ovata would produce less resin than hydrated plants. Our null hypothesis was that there is no significant difference ...


Corn Nitrogen Fertilization Requirement And Corn–Soybean Productivity With A Rye Cover Crop, Jose L. Pantoja, Krishna P. Woli, John E. Sawyer, Daniel W. Barker 2017 Universidad de las Fuerzas Armadas Pichincha

Corn Nitrogen Fertilization Requirement And Corn–Soybean Productivity With A Rye Cover Crop, Jose L. Pantoja, Krishna P. Woli, John E. Sawyer, Daniel W. Barker

John E. Sawyer

Winter rye (Secale cereale L.) cover crop (RCC) has potential to reduce NO3–N loss from corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] fields. However, RCC effects on annual crop productivity and corn optimal N fertilization requirement are unclear. The objectives were to evaluate corn and soybean yield response to RCC and corn optimal N rate. Treatments were no-RCC and RCC with six fertilizer N rates (0–225 kg N ha-1) applied to corn in a no-till corn–soybean (CS) rotation at four Iowa sites in 2009 through 2011. The RCC biomass and N uptake was low ...


Agronomic Comparison Of Anhydrous Ammonia Applied With A High Speed-Low Draft Opener And Conventional Knife Injection In Corn, Krishna P. Woli, Fabián G. Fernández, John E. Sawyer, Joshua D. Stamper, David B. Mengel, Daniel W.. Barker, Mark H. Hanna 2017 Iowa State University

Agronomic Comparison Of Anhydrous Ammonia Applied With A High Speed-Low Draft Opener And Conventional Knife Injection In Corn, Krishna P. Woli, Fabián G. Fernández, John E. Sawyer, Joshua D. Stamper, David B. Mengel, Daniel W.. Barker, Mark H. Hanna

John E. Sawyer

Anhydrous ammonia (AA) is an important N fertilizer in the U.S., and with large farming operations rapid application is needed. This study evaluated the impact of AA application timing and N rates when applied with a high speed low draft (HSLD) or a conventional till knife (CTKI) on corn (Zea Mays L.) production in no-tillage fields. The study was conducted at sites located in Illinois, Iowa, and Kansas from 2007 to 2009. The experimental design was a split-plot factorial arrangement of application method, timing (fall; spring preplant, SP; and sidedress, SD), and five N rates. Fall AA application was ...


Phosphorus Indexing For Cropland: Overview And Basic Concepts Of The Iowa Phosphorus Index, A. P. Mallarino, B. M. Stewart, J. L. Baker, J. D. Downing, J. E. Sawyer 2017 Iowa State University

Phosphorus Indexing For Cropland: Overview And Basic Concepts Of The Iowa Phosphorus Index, A. P. Mallarino, B. M. Stewart, J. L. Baker, J. D. Downing, J. E. Sawyer

John E. Sawyer

Excessive phosphorus (P) loss from soils impairs surface water resources. An assessment tool or index has been proposed to identify fields with high potential risk of P delivery. The P index integrates P source and transport factors into a decision making process that may lead to changes in current P management and soil conservation practices. The index recognizes that a single soil P threshold alone is not an appropriate evaluation factor because of the varying conditions across fields. Although most indices being developed in the United States include similar factors, source and transport characteristics are considered in various ways to ...


Does Nitrogen Fertilizer Application Rate To Corn Affect Nitrous Oxide Emissions From The Rotated Soybean Crop?, Javed Iqbal, David C. Mitchell, Daniel W. Barker, Fernando Miguez, John E. Sawyer, Jose Pantoja, Michael J. Castellano 2017 Iowa State University

Does Nitrogen Fertilizer Application Rate To Corn Affect Nitrous Oxide Emissions From The Rotated Soybean Crop?, Javed Iqbal, David C. Mitchell, Daniel W. Barker, Fernando Miguez, John E. Sawyer, Jose Pantoja, Michael J. Castellano

John E. Sawyer

Little information exists on the potential for N fertilizer application to corn (Zea mays L.) to affect N2O emissions during subsequent unfertilized crops in a rotation. To determine if N fertilizer application to corn affects N2O emissions during subsequent crops in rotation, we measured N2O emissions for 3 yr (2011–2013) in an Iowa, corn–soybean [Glycine max (L.) Merr.] rotation with three N fertilizer rates applied to corn (0 kg N ha−1, the recommended rate of 135 kg N ha−1, and a high rate of 225 kg N ha−1); soybean ...


Standardized Research Protocols Enable Transdisciplinary Research Of Climate Variation Impacts In Corn Production Systems, E. J. Kladivko, M. J. Helmers, L. J. Abendroth, D. Herzmann, R. Lal, M. J. Castellano, D. S. Mueller, J. E. Sawyer, R. P. Anex, R. W. Arritt, B. Basso, J. V. Bonta, L. C. Bowling, R. M. Cruse, N. R. Fausey, J. R. Frankenberger, P. W. Gassman, A. J. Gassmann, C. L. Kling, A. Kravchenko, J. G. Lauer, F. E. Miguez, E. D. Nafziger, N. Nkongolo, M. O'Neal, L. B. Owens, P. R. Owens, P. Scharf, M. J. Shipitalo, J. S. Strock, M. B. Villamil 2017 Purdue University

Standardized Research Protocols Enable Transdisciplinary Research Of Climate Variation Impacts In Corn Production Systems, E. J. Kladivko, M. J. Helmers, L. J. Abendroth, D. Herzmann, R. Lal, M. J. Castellano, D. S. Mueller, J. E. Sawyer, R. P. Anex, R. W. Arritt, B. Basso, J. V. Bonta, L. C. Bowling, R. M. Cruse, N. R. Fausey, J. R. Frankenberger, P. W. Gassman, A. J. Gassmann, C. L. Kling, A. Kravchenko, J. G. Lauer, F. E. Miguez, E. D. Nafziger, N. Nkongolo, M. O'Neal, L. B. Owens, P. R. Owens, P. Scharf, M. J. Shipitalo, J. S. Strock, M. B. Villamil

John E. Sawyer

The important questions about agriculture, climate, and sustainability have become increasingly complex and require a coordinated, multifaceted approach for developing new knowledge and understanding. A multistate, transdisciplinary project was begun in 2011 to study the potential for both mitigation and adaptation of corn-based cropping systems to climate variations. The team is measuring the baseline as well as change of the system's carbon (C), nitrogen (N), and water footprints, crop productivity, and pest pressure in response to existing and novel production practices. Nine states and 11 institutions are participating in the project, necessitating a well thought out approach to coordinating ...


Impacts Of Climate Change On Hydrology, Water Quality And Crop Productivity In The Ohio-Tennessee River Basin, Yiannis Panagopoulos, Philip W. Gassman, Raymond W. Arritt, Daryl E. Herzmann, Todd D. Campbell, Adriana Valcu, Manoj K. Jha, Catherine L. Kling, Raghavan Srinivasan, Michael White, Jeffrey G. Arnold 2017 Iowa State University

Impacts Of Climate Change On Hydrology, Water Quality And Crop Productivity In The Ohio-Tennessee River Basin, Yiannis Panagopoulos, Philip W. Gassman, Raymond W. Arritt, Daryl E. Herzmann, Todd D. Campbell, Adriana Valcu, Manoj K. Jha, Catherine L. Kling, Raghavan Srinivasan, Michael White, Jeffrey G. Arnold

Catherine Kling

Nonpoint source pollution from agriculture is the main source of nitrogen and phosphorus in the stream systems of the Corn Belt region in the Midwestern US. The eastern part of this region is comprised of the Ohio-Tennessee River Basin (OTRB), which is considered a key contributing area for water pollution and the Northern Gulf of Mexico hypoxic zone. A point of crucial importance in this basin is therefore how intensive corn-based cropping systems for food and fuel production can be sustainable and coexist with a healthy water environment, not only under existing climate but also under climate change conditions in ...


The Fungicidal Action Of Formaldehyde, I. E. Melhus, J. C. Gilman, J. B. Kendrick 2017 Iowa State College

The Fungicidal Action Of Formaldehyde, I. E. Melhus, J. C. Gilman, J. B. Kendrick

Research Bulletin (Iowa Agriculture and Home Economics Experiment Station)

'rhe work presented in this bulletin attempts to open up this field of investigation and supply data bearing on the toxic action of formaldehyde and the influence thereon of concentration of the solution, of temperature of treatment and of duration of exposure. The data is limited to two organisms, Actinomyces scabies and Rhizocttpmoia solani, as they occur on the surfaces of potato tubers. Both laboratory and field work were carried on, altho the latter was limited due to the time required to get results and the non-controlled external factors which influence such results.


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