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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 ...


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 ...


Studies On The Crown Rust Of Oats, I. E. Melhus, L. W. Durrell 2017 Iowa State College

Studies On The Crown Rust Of Oats, I. E. Melhus, L. W. Durrell

Research Bulletin (Iowa Agriculture and Home Economics Experiment Station)

During some seasons crown rust of oats (Puccinia coronata Corda) becomes a serious limiting factor in successful oat production in Iowa. It is not uncommon to have this rust occur in epidemic form one year and the following year to have only a small amount of the disease present. Up to the present time the various factors which influence the growth, development and epidemiology of this rust have not been definitely studied.


Yellow Corn, Wet Soils, And N Loss – Part 2, John E. Sawyer 2017 Iowa State University

Yellow Corn, Wet Soils, And N Loss – Part 2, John E. Sawyer

John E. Sawyer

Last week (June 19) I provided some observations on corn growth and response to nitrogen (N) applied in an anhydrous ammonia study being conducted at the ISU research farm between Ames and Boone. Following are some observations one week later (June 26, 2008).


Update To Iowa Phosphorus, Potassium And Lime Recommendations, Antonio P. Mallarino, John E. Sawyer 2017 Iowa State University

Update To Iowa Phosphorus, Potassium And Lime Recommendations, Antonio P. Mallarino, John E. Sawyer

John E. Sawyer

This article highlights revisions to Iowa State University (ISU) soil-test interpretations and application guidelines for phosphorus (P), potassium (K) and lime in an update of extension publication PM 1688 "A General Guide for Crop Nutrient and Limestone Recommendations in Iowa." The printed version of this publication will not be ready until later in the fall and the online version should be posted by early October at the Extension Online Store and on the Soil Fertility web site. Field research is conducted continuously to assure that nutrient management suggestions are up to date. This research has indicated that some recommendations should ...


Sensing Nitrogen Stress In Corn, John E. Sawyer, John Lundvall, Jennifer S. Hawkins, Daniel W. Barker 2017 Iowa State University

Sensing Nitrogen Stress In Corn, John E. Sawyer, John Lundvall, Jennifer S. Hawkins, Daniel W. Barker

John E. Sawyer

Determining the proper nitrogen (N) fertilization rate is important for the economic viability of corn production. A desire for high yields, fueled by low fertilizer N costs, led producers to apply rates that ensured adequate N rather than risk costly yield losses due to a shortage of N. Due to water quality concerns and recently high N fertilizer prices, management strategies are needed that can improve the efficiency and profitability of N use. With N application rates based on economic return instead of maximizing productivity, producers want to confirm that rate decisions are working adequately. Also, if unexpected N losses ...


Seasonal And Rotational Influences On Corn Nitrogen Requirements, Armstrong Farm, John E. Sawyer, Daniel W. Barker 2017 Iowa State University

Seasonal And Rotational Influences On Corn Nitrogen Requirements, Armstrong Farm, John E. Sawyer, Daniel W. Barker

John E. Sawyer

This project is designed to study nitrogen (N) fertilization needs in continuous corn (C-C) and corn rotated with soybeans (C-S) as influenced by location and climate. Multiple rates of N fertilizer are 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 help determine N requirements for each rotational practice, differences that exist between the two rotations and responses to applied N across different soils and climatic conditions. It will also allow for the evaluation of tools used to adjust N application.


Seasonal And Rotational Influences On Corn Nitrogen Requirements, Swine Farm, John E. Sawyer, Daniel W. Barker 2017 Iowa State University

Seasonal And Rotational Influences On Corn Nitrogen Requirements, Swine Farm, John E. Sawyer, Daniel W. Barker

John E. Sawyer

This project is designed to study nitrogen (N) fertilization needs in continuous corn (C-C) and corn rotated with soybeans (C-S) as influenced by location and climate. Multiple rates of N fertilizer are 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 help determine N requirements for each rotational practice, differences that exist between the two rotations, and responses to applied N across different soils and climatic conditions. It will also allow for the evaluation of tools used to adjust N application.


Seasonal And Rotational Influences On Corn Nitrogen Requirements, John E. Sawyer, Daniel W. Barker 2017 Iowa State University

Seasonal And Rotational Influences On Corn Nitrogen Requirements, John E. Sawyer, Daniel W. Barker

John E. Sawyer

This project was designed to study the nitrogen (N) fertilization needs in continuous corn (C-C) and corn rotated with soybean (C-S) 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 the determination of N requirements for each rotation practice, differences that exist between the two rotations, responses to N applied across different soils and climatic conditions, and evaluation of tools used to adjust N application.


Seasonal And Rotational Influences On Corn Nitrogen Requirements, John E. Sawyer, Daniel W. Barker 2017 Iowa State University

Seasonal And Rotational Influences On Corn Nitrogen Requirements, John E. Sawyer, Daniel W. Barker

John E. Sawyer

This project is designed to study the N fertilization needs in continuous corn (C-C) and corn rotated with soybean (C-S) as influenced by location and climate. Multiple rates of fertilizer N are 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 help determine N requirements for each rotation practice, differences that exist between the two rotations, responses to applied N across different soils and different climatic conditions. It will also allow for the evaluation of tools used to adjust N application.


Seasonal And Rotational Influences On Corn Nitrogen Requirements, John E. Sawyer, Daniel W. Barker 2017 Iowa State University

Seasonal And Rotational Influences On Corn Nitrogen Requirements, John E. Sawyer, Daniel W. 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 the 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.


Seasonal And Rotational Influences On Corn Nitrogen Requirements, John E. Sawyer, Daniel W. Barker 2017 Iowa State University

Seasonal And Rotational Influences On Corn Nitrogen Requirements, John E. Sawyer, Daniel W. Barker

John E. Sawyer

This project is designed to study the N fertilization needs as influenced by location and climate in continuous corn and corn rotated with soybean. Multiple rates of fertilizer N are 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 the determination of N requirements for each rotation practice, 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.


Seasonal And Rotational Influences On Corn Nitrogen Requirements, John E. Sawyer, Daniel W. Barker 2017 Iowa State University

Seasonal And Rotational Influences On Corn Nitrogen Requirements, John E. Sawyer, Daniel W. 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.


Seasonal And Rotational Influences On Corn Nitrogen Requirements, John E. Sawyer, Daniel W. Barker 2017 Iowa State University

Seasonal And Rotational Influences On Corn Nitrogen Requirements, John E. Sawyer, Daniel W. 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 are 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 the 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.


Seasonal And Rotational Influences On Corn Nitrogen Requirements, John E. Sawyer, Daniel W. Barker 2017 Iowa State University

Seasonal And Rotational Influences On Corn Nitrogen Requirements, John E. Sawyer, Daniel W. 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 the 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.


Seasonal And Rotational Influences On Corn Nitrogen Requirements, John E. Sawyer, Daniel W. Barker 2017 Iowa State University

Seasonal And Rotational Influences On Corn Nitrogen Requirements, John E. Sawyer, Daniel W. 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.


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