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Full-Text Articles in Life Sciences

Investigations Into The Function Of Common Milkweed (Asclepias Syriaca) In The Agricultural Landscape, Sydney Lizotte-Hall Jan 2018

Investigations Into The Function Of Common Milkweed (Asclepias Syriaca) In The Agricultural Landscape, Sydney Lizotte-Hall

Graduate Theses and Dissertations

The monarch butterfly’s (Danaus plexippus Linnaeus) vibrant orange color with contrasting black veins and white spots make it recognizable to many. Unfortunately, the remarkable migration made by the eastern monarch population is at risk due to the recent decline in this cohort of the species. Many factors are said to have caused the decline, including overwintering habitat destruction, increased dependence on herbicide-tolerant crops, extreme climatic events, predation, loss of breeding habitat, etc.

Two studies were conducted to: 1) determine the impact of sub-lethal herbicides on growth of common milkweed and utilization by monarchs and 2) investigate simple methods for ...


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 ...


Why Manage Phosphorus?, John E. Sawyer, Antonio P. Mallarino Mar 2017

Why Manage Phosphorus?, John E. Sawyer, Antonio P. Mallarino

John E. Sawyer

There are 17 nutrients that are essential for plant growth and production. An insufficient supply of one or more can have an adverse effect on plant growth, maturity, and yield. Phosphorus (P)--one of three key macronutrients (nitrogen and potassium are the other two)--is present in every living plant and animal cell, and is vital in plants for harvesting the sun's energy for growth and reproduction. This requirement is the same whether the plant is growing on soil or in water (such as algae); hence, the concern regarding P levels in surface water and the accelerated aquatic plant ...


Yellow Corn, Wet Soils, And Nitrogen Loss (Part 3), John E. Sawyer Mar 2017

Yellow Corn, Wet Soils, And Nitrogen Loss (Part 3), John E. Sawyer

John E. Sawyer

Earlier I provided observations in two articles (June 19 and June 26, 2008) 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 final observations (July 7, 2008).


Wait Until Soil Temps Drop Before Applying Anhydrous Ammonia, John E. Sawyer, Barbara Stewart, William Ehm Mar 2017

Wait Until Soil Temps Drop Before Applying Anhydrous Ammonia, John E. Sawyer, Barbara Stewart, William Ehm

John E. Sawyer

With the early harvest, Iowa’s conservation leaders are encouraging farmers to wait until soil temperatures lower before applying anhydrous ammonia (NH3) this fall. Anhydrous ammonia applied before daily soil temperatures remain below 50 degrees Fahrenheit and continue trending lower can result in the nitrogen loss that can impact crop development and have negative environmental impacts, such as enhanced leaching into groundwater and streams once converted to nitrate.


Wet Conditions And Change In Soil Profile Nitrate, John E. Sawyer Mar 2017

Wet Conditions And Change In Soil Profile Nitrate, John E. Sawyer

John E. Sawyer

I wrote an ICM News article February 21, 2013, that provided a summary of fall soil profile nitrate sampling results following the 2012 corn harvest. As I cautioned in that and other articles, the amount of nitrate-N that might remain for a 2013 corn crop depends on springtime rainfall. Unfortunately, much of Iowa has received considerable precipitation since soils thawed, especially the eastern two-thirds of Iowa. The two maps of the Midwest region show the total precipitation and deviation from normal since March 7, 2013. Tile lines are flowing again, and nitrate in the profile will move with percolating water ...


Uan And Preemergence Herbicide Applications On Emerged Corn, Michael D. Owen, John E. Sawyer, Robert G. Hartzler Mar 2017

Uan And Preemergence Herbicide Applications On Emerged Corn, Michael D. Owen, John E. Sawyer, Robert G. Hartzler

John E. Sawyer

Planting the Iowa 2007 corn crop is somewhat behind recent years, and in efforts to stay ahead of the game, many fields will be planted before being treated with nitrogen (N) and/or herbicides. Corn in some of these fields will emerge before applications of these materials are made, raising concerns over the safety of postemergence applications of urea-ammonium nitrate (UAN) solution, with or without herbicides.


Soybean Top Dieback Shows Up In Iowa Again, Xiao-Bing Yang, John E. Sawyer Mar 2017

Soybean Top Dieback Shows Up In Iowa Again, Xiao-Bing Yang, John E. Sawyer

John E. Sawyer

Extension field agronomists report the occurrence of soybean top dieback in northeastern Iowa soybean fields this week. Soybean top dieback symptoms have shown up occasionally since it was first reported by Jim Fawcett and Jerry Long in Cedar County a few years ago. Last year it was also found in eastern and central Iowa.


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

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 soybeans (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 allow the determination of N requirements for each rotation 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 ...


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

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 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 Mar 2017

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, John Lundvall Mar 2017

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

John E. Sawyer

This project is designed to study the N fertilization needs of continuous corn (C-C) and corn rotated with soybeans (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 rotational practice, differences that exist between the two rotations, and responses to applied N across different soils and different climatic conditions. It will also allow for the evaluation of tools used to adjust N ...


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

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 Mar 2017

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 Mar 2017

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 Mar 2017

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 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.


Phosphorus And Potassium In Silage Harvest Of Drought-Damaged Corn, John E. Sawyer, Antonio P. Mallarino Mar 2017

Phosphorus And Potassium In Silage Harvest Of Drought-Damaged Corn, John E. Sawyer, Antonio P. Mallarino

John E. Sawyer

The dry conditions this summer are resulting in quite variable corn growth and production potential. Some livestock producers are beginning harvest of corn damaged by drought conditions for silage. Corn silage harvest results in more phosphorus (P) and potassium (K) removal than grain alone because almost the entire plant is harvested. The increased amount removed with silage differs for P and K because the relative amount of P and K is different in corn vegetative parts than in grain. For P there can be approximately four times greater amount of P per ton of dry matter in grain than vegetative ...


Nitrogen Loss: How Does It Happen?, John E. Sawyer Mar 2017

Nitrogen Loss: How Does It Happen?, John E. Sawyer

John E. Sawyer

For the period April 1 through May 6, 2007, much of Iowa received more than 5 inches of rainfall (May 6, 2007 AWIS Inc. report). The Northwest, North-Central, and East-Central districts averaged slightly less than 5 inches, and the West-Central and Southwest districts more than 9 inches. With the large rainfall and flooding conditions, many producers are wondering about nitrogen (N) losses. While this period certainly has an influence on N in the soil, excessively wet conditions later in the spring are especially important for N losses. Early to mid-June will be a critical period to assess crop growth and ...


Measurements In Support Of Wind Farm Simulations And Power Forecasts: The Crop/Wind-Energy Experiments (Cwex), Eugene S. Takle, Daniel Andrew Rajewski, J. K. Lundquist, William A. Gallus Jr., Anupam Sharma Feb 2017

Measurements In Support Of Wind Farm Simulations And Power Forecasts: The Crop/Wind-Energy Experiments (Cwex), Eugene S. Takle, Daniel Andrew Rajewski, J. K. Lundquist, William A. Gallus Jr., Anupam Sharma

Anupam Sharma

The Midwest US currently is experiencing a large build-out of wind turbines in areas where the nocturnal low-level jet (NLLJ) is a prominent and frequently occurring feature. We describe shear characteristics of the NLLJ and their influence on wind power production. Reports of individual turbine power production and concurrent measurements of near-surface thermal stratification are used to turbine wake interactions and turbine interaction with the overlying atmosphere. Progress in forecasting conditions such as wind ramps and shear are discussed. Finally, the pressure perturbation introduced by a line of turbines produces surface flow convergence that may create a vertical velocity and ...


Kansas Field Research 2017, Kansas State University Jan 2017

Kansas Field Research 2017, Kansas State University

Kansas Agricultural Experiment Station Research Reports

Kansas Agricultural Experiment Station Research Reports from research field locations.


Soil And Plant Property Differences Among High-Yield Soybean Areas In Arkansas, Taylor Cass Adams Dec 2016

Soil And Plant Property Differences Among High-Yield Soybean Areas In Arkansas, Taylor Cass Adams

Theses and Dissertations

Continued achievement of soybean [Glycine max (L.) Merr.] yields greater than 6719 kg ha-1 (100 bu ac-1) will depend on decreasing the yield gap, which is contingent on gathering more information regarding the soil physical, chemical, and microbiological environment and the main plant factors contributing to high-yield soybean. Therefore, understanding the main factor differences between high- and average-yield areas may provide insight for making management decisions to increase yields. The objectives of this study were i) to evaluate the effects of region and soil depth on soil property differences between high- and average-soybean-yielding areas, ii) to determine which soil properties ...


Agronomic Options For Profitable Rice-Based Farming System In Northern Australia, Siva Sivapalan Sep 2016

Agronomic Options For Profitable Rice-Based Farming System In Northern Australia, Siva Sivapalan

Contributions to Books & Books

Minimum air temperatures less than 15°C had biggest impact on varietal performance. Cold damage during the months of June and July warrants selection of varieties with cold tolerance for this environment, especially for the aerobic rice system. Ponded water has 4-8°C advantage over the air temperature, thus providing some protection against such cold damage. This has resulted in higher yields under flooded system. Planting dates, varying from late-February to late-May, were found to play a crucial role for plants to escape the low temperature damage at critical growth stages. Among the varieties tested, selected tropical varieties yielded higher ...


The Illinois Soil Nitrogen Test: Should It Be Used In Iowa?, John E. Sawyer, Mohammod Ali Tabatabai Jul 2016

The Illinois Soil Nitrogen Test: Should It Be Used In Iowa?, John E. Sawyer, Mohammod Ali Tabatabai

John E. Sawyer

The test was developed several years ago at the University of Illinois by researchers in the Department of Natural Resources and Environmental Sciences. It is a laboratory procedure designed to measure N liberated from soil heated for 5 hours with dilute alkali solution (sodium hydroxide). The test does not measure nitrate, but does measure exchangeable ammonium and a fraction of soil organic N.


Sulfur Fertilizer Application To Corn And Soybean, John E. Sawyer, Daniel W. Barker Jul 2016

Sulfur Fertilizer Application To Corn And Soybean, John E. Sawyer, Daniel W. Barker

John E. Sawyer

Historically sulfur (S) application has not been recommended on Iowa soils for corn and soybean production. The soil supply or combination from sources such as manure or precipitation has met crop S needs. However, soil S levels or supply will become depleted with prolonged crop removal, sulfate leaching, low precipitation deposition, and declining soil organic matter. The objective of this study was to determine the responsiveness of corn and soybean to S application (first year and residual second year) and S fertilizer material at multiple sites across Iowa soils and climatic conditions.


Sulfur Fertilizer Application To Corn And Soybean, John E. Sawyer, Daniel W. Barker Jul 2016

Sulfur Fertilizer Application To Corn And Soybean, John E. Sawyer, Daniel W. Barker

John E. Sawyer

Historically, sulfur (S) application has not been recommended on Iowa soils for corn and soybean production. Soil supply or combination from sources such as manure or precipitation has met crop S needs. However, soil S levels or supply may become depleted with prolonged crop removal, sulfate leaching, low precipitation deposition, and declining soil organic matter. The objective of this study was to determine if corn and soybean yields would respond to S fertilizer rate and material at multiple sites across Iowa soils and climatic conditions.


Sulfur Fertilizer Application To Corn And Soybean, John E. Sawyer, Daniel W. Barker Jul 2016

Sulfur Fertilizer Application To Corn And Soybean, John E. Sawyer, Daniel W. Barker

John E. Sawyer

Historically sulfur (S) application has not been recommended on Iowa soils for corn and soybean production. The soil supply or combination from sources such as manure or precipitation has met crop S needs. However, soil S levels or supply will become depleted with prolonged crop removal, sulfate leaching, low precipitation deposition, and declining soil organic matter. The objective of this study was to determine the responsiveness of corn and soybean to S application (first year and residual second year) and S fertilizer material at multiple sites across Iowa soils and climatic conditions.


Sulfur Fertilizer Application To Corn And Soybean, John E. Sawyer, Daniel W. Barker Jul 2016

Sulfur Fertilizer Application To Corn And Soybean, John E. Sawyer, Daniel W. Barker

John E. Sawyer

Historically sulfur (S) application has not been recommended on Iowa soils for corn and soybean production. The soil supply or combination from sources such as manure or precipitation has met crop S needs. However, soil S levels or supply will become depleted with prolonged crop removal, sulfate leaching, low precipitation deposition, and declining soil organic matter. The objective of this study was to determine the responsiveness of corn and soybean to S application (first year and residual second year) and S fertilizer material at multiple sites across Iowa soils and climatic conditions.


Sulfur Fertilizer Application To Corn And Soybean, John E. Sawyer, Daniel W. Barker Jul 2016

Sulfur Fertilizer Application To Corn And Soybean, John E. Sawyer, Daniel W. Barker

John E. Sawyer

Historically, sulfur (S) application has not been recommended on Iowa soils for corn and soybean production. Soil supply or combination from sources such as manure or precipitation has met crop S needs. However, soil S levels or supply may become depleted with prolonged crop removal, sulfate leaching, low precipitation deposition, and declining soil organic matter. The objective of this study was to determine if corn and soybean yields would respond to S fertilizer rate and material at multiple sites across Iowa soils and climatic conditions.


Sulfur Fertilizer Application To Corn And Soybean, John E. Sawyer, Daniel W. Barker Jul 2016

Sulfur Fertilizer Application To Corn And Soybean, John E. Sawyer, Daniel W. Barker

John E. Sawyer

Historically sulfur (S) application has not been recommended on Iowa soils for corn and soybean production. The soil supply or combination from sources such as manure or precipitation has met crop S needs. However, soil S levels or supply will become depleted with prolonged crop removal, sulfate leaching, low precipitation deposition, and declining soil organic matter. The objective of this study was to determine the responsiveness of corn and soybean to S application (first year and residual second year) and S fertilizer material at multiple sites across Iowa soils and climatic conditions.


Summary Of Sulfur Strip Trials Conducted In Central And Northeast Iowa Preliminary 2009 Results, John E. Sawyer, Daniel W. Barker, Brian J. Lang Jul 2016

Summary Of Sulfur Strip Trials Conducted In Central And Northeast Iowa Preliminary 2009 Results, John E. Sawyer, Daniel W. Barker, Brian J. Lang

John E. Sawyer

Sulfur (S) strip trials were conducted by ISU Extension field agronomists Brian Lang, George Cummins, and Mark Wuebker; Heartland Co-op; Innovative Ag; Five Star Co-op; Calcium Products, Inc; and cooperating growers.