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Physical Sciences and Mathematics Commons

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Full-Text Articles in Physical Sciences and Mathematics

Alpine Plant Communities Of The White Mountains Of New Hampshire: Aboveground Plant Diversity And Abundance Correlated To Belowground Factors, Timothy Maddalena-Lucey Jan 2019

Alpine Plant Communities Of The White Mountains Of New Hampshire: Aboveground Plant Diversity And Abundance Correlated To Belowground Factors, Timothy Maddalena-Lucey

Antioch University Full-Text Dissertations & Theses

Alpine plant communities are fragile complex systems that may be threatened by climate change. Patterns of climate-driven soil warming are shown to have lasting effects on ecosystem nutrient cycles, alpine plant phenology, and belowground soil biotic activity. There are concerns in the alpine mycorrhizal research community as to how belowground fungal biomass will react to climate-driven soil warming. To address these concerns I asked in this study what are the correlations between belowground factors such as collective ectomycorrhizal (EcM) and ericoid mycorrhizal (ErM) percent colonization, pH, and soil depth to bedrock and aboveground plant diversity and richness. In 2018, on …


Winter Grazing Management, Stephen K. Barnhart, James R. Russell, Douglas L. Karlen, Michael J. Tidman Jun 2017

Winter Grazing Management, Stephen K. Barnhart, James R. Russell, Douglas L. Karlen, Michael J. Tidman

Douglas L Karlen

Why winter grazing? Beef cow herd and sheep flock records show that winter feeding costs are livestock producers' single largest production expense. Managing through winter weather while keeping feeding costs low is an essential part of maintaining a profitable operation. Iowa's climate generally allows forage growth only during a 7-to-8 month period. Extending the grazing of this forage--even an extra 3 or 4 weeks in late autumn and winter--is an economical way to maintain or increase livestock profitability. Some producers extend the grazing season by using stockpiled forage, whereas others use crop residue, and many combine the use of stockpiled …


In-Season N Fertilization Strategies Using Active Sensors, Daniel Barker, John Sawyer Jul 2016

In-Season N Fertilization Strategies Using Active Sensors, Daniel Barker, John Sawyer

John E. Sawyer

The objectives of this project were to measure corn yield response to applied nitrogen (N) fertilizer based on active canopy sensing during the mid-vegetative corn growth stage (V10) and compare yield and N use efficiency between pre-plant N (PP-N), pre-plant + sensor N (PP+S-N), split N strategy (SNS), and rescue N strategy (RNS).


In-Season N Fertilization Strategies Using Active Sensors, Daniel Barker, John Sawyer Jul 2016

In-Season N Fertilization Strategies Using Active Sensors, Daniel Barker, John Sawyer

John E. Sawyer

The objectives of this project were to measure corn yield response to applied nitrogen (N) fertilizer based on active canopy sensing during the mid-vegetative corn growth stage (V10) and compare yield and N use efficiency between pre-plant N (PP-N), pre-plant + sensor N (PP+S-N), split N strategy (SNS), and rescue N strategy (RNS).


In-Season N Fertilization Strategies Using Active Sensors, Daniel Barker, John Sawyer Jul 2016

In-Season N Fertilization Strategies Using Active Sensors, Daniel Barker, John Sawyer

John E. Sawyer

The objectives of this project were to measure corn yield response to applied nitrogen (N) fertilizer based on active canopy sensing during the mid-vegetative corn growth stage (V10) and compare yield and N use efficiency between pre-plant N (PP-N), pre-plant + sensor N (PP+S-N), split N strategy (SNS), and rescue N strategy (RNS).


In-Season N Fertilization Strategies Using Active Sensors, Daniel Barker, John Sawyer Jul 2016

In-Season N Fertilization Strategies Using Active Sensors, Daniel Barker, John Sawyer

John E. Sawyer

The objectives of this project were to measure corn yield response to applied nitrogen (N) fertilizer based on active canopy sensing during the mid-vegetative corn growth stage (V10) and compare yield and N use efficiency between pre-plant N (PP-N), pre-plant + sensor N (PP+S-N), split N strategy (SNS), and rescue N strategy (RNS).


In-Season N Fertilization Strategies Using Active Sensors, Daniel Barker, John Sawyer Jul 2016

In-Season N Fertilization Strategies Using Active Sensors, Daniel Barker, John Sawyer

John E. Sawyer

The objectives of this project were to measure corn yield response to applied nitrogen (N) fertilizer based on active canopy sensing during the mid-vegetative corn growth stage (V10) and compare yield and N use efficiency between pre-plant N (PP-N), pre-plant + sensor N (PP+S-N), split N strategy (SNS), and rescue N strategy (RNS).


In-Season N Fertilization Strategies Using Active Sensors, Daniel Barker, John Sawyer Jul 2016

In-Season N Fertilization Strategies Using Active Sensors, Daniel Barker, John Sawyer

John E. Sawyer

The objectives of this project were to measure corn yield response to applied nitrogen (N) fertilizer based on active canopy sensing during the mid-vegetative corn growth stage (V10) and compare yield and N use efficiency between pre-plant N (PP-N), pre-plant + sensor N (PP+S-N), split N strategy (SNS), and rescue N strategy (RNS).


Impacts Of Cover Crops On Phosphorus And Nitrogen Loss With Surface Runoff, Antonio Mallarino, Richard Cruse, Dan Jaynes, John Sawyer, Pablo Barbieri Jul 2016

Impacts Of Cover Crops On Phosphorus And Nitrogen Loss With Surface Runoff, Antonio Mallarino, Richard Cruse, Dan Jaynes, John Sawyer, Pablo Barbieri

John E. Sawyer

Iowa research has demonstrated that cover crops can improve soil productivity and water quality by increasing soil organic matter and reducing nitrate nitrogen (N) leaching. Other research has investigated and is investigating the agronomic and economic viability of using cereal rye cover crops in continuous corn or corn-soybean rotations. However, no Iowa research has evaluated under natural rainfall the impact of cover crops on phosphorus (P) and N loss with surface runoff interacting with other management practices. The need for this type of research was indicated in the Iowa Nutrient Reduction Strategy documents. This effort assessed what would be needed …


Impact Of 4r Management On Crop Production And Nitrate-Nitrogen Loss In Tile Drainage, Matthew Helmers, John Sawyer, Josh Sievers Jul 2016

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

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 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.