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Full-Text Articles in Physical Sciences and Mathematics

Evaluation Of Soybean Maturity Group And Planting Date In A Soybean-Rice Rotation On Overall Crop Productivity, Carrie Ortel Dec 2018

Evaluation Of Soybean Maturity Group And Planting Date In A Soybean-Rice Rotation On Overall Crop Productivity, Carrie Ortel

Theses and Dissertations

Little is known about the effects of soybean (Glycine max L.) management techniques on soil-nitrogen (N) credit development and its impact on the subsequent rice (Oryza sativa L.) crop’s success. This study was conducted to determine how soybean maturity group (MG) and planting date effect overall soybean productivity and its influence on the following rice crop. Various soybean planting dates (optimum and late) and MGs (3.5, 4.7, 5.4, and 5.6) were grown and followed in rotation with a rice crop. Six rates of pre-flood fertilizer-N (0, 44, 89, 134, 179, 224 kg N ha-1) were ...


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 ...


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

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

Daniel W. Barker

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 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.


In-Season N Fertilization Strategies Using Active Sensors, Daniel Barker, John Sawyer Jun 2017

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

Daniel W. Barker

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 Jun 2017

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

Daniel W. Barker

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 Jun 2017

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

Daniel W. Barker

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 Jun 2017

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

Daniel W. Barker

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 Jun 2017

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

Daniel W. Barker

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 Jun 2017

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

Daniel W. Barker

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).


The Impacts Of Climate Change On Stream Flow In The Upper Mississippi River Basin: A Regional Climate Model Perspective, Manoj K. Jha, Zaitao Pan, Eugene S. Takle, Roy R. Gu Apr 2017

The Impacts Of Climate Change On Stream Flow In The Upper Mississippi River Basin: A Regional Climate Model Perspective, Manoj K. Jha, Zaitao Pan, Eugene S. Takle, Roy R. Gu

Eugene Takle

We evaluate the impact of climate change on stream flow in the Upper Mississippi River Basin (UMRB) by using a regional climate model (RCM) coupled with a hydrologic model, the Soil and Water Assessment Tool (SWAT). The SWAT model was calibrated and validated against measured stream flow data using observed weather data and inputs from the Environmental Protection Agency’s BASINS (Better Assessment Science Integrating Point and Nonpoint Sources) geographical information/database system. The combined performance of the SWAT and RCM was examined using observed weather data as a lateral boundary condition in the RCM. The SWAT and RCM were ...


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 ...


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 ...


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.


Interpreting P And K Soil Test Results, John E. Sawyer, Antonio P. Mallarino Jul 2016

Interpreting P And K Soil Test Results, John E. Sawyer, Antonio P. Mallarino

John E. Sawyer

Soil testing is a key component for determining the need for phosphorus (P) and potassium (K) fertilization. Also, if fertilization is required, test results guide the rate of application recommended to optimize production. Through extensive field research, specific soil tests are calibrated against the expectation of response to applied P and K; that is, they provide both a relative index of the availability of P and K to the crop being grown and an indication of the magnitude of yield increase one might expect when nutrients are applied, thus providing the interpretation of text results.


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).


Drought Impacts On Soil Fertility Management, John E. Sawyer Jul 2016

Drought Impacts On Soil Fertility Management, John E. Sawyer

John E. Sawyer

If crop production was severely reduced because of dry conditions this year, there are a few items you can consider when planning for next year's crop. One, with severely damaged crops and low yields you might credit some of the phosphorus (P) and potassium (K) applied for this year's crop to next year, as much less removal will occur in grain harvest of the lower than expected yield.


Corn Stalk Nitrate Interpretation, John E. Sawyer Jul 2016

Corn Stalk Nitrate Interpretation, John E. Sawyer

John E. Sawyer

You’ve gotten results from corn stalk nitrate samples collected this fall. (Corn stalk nitrate analysis form.) Now, what do the results mean? The stalk nitrate test is based on the concentration of nitrate-N in the lower corn stalk (8 inch segment from 6 to 14 inches above the ground) when the plant reaches maturity (See Cornstalk testing to evaluate nitrogen management, PM 1584). In general, a larger amount of plant-available N in the soil during the time period before plant maturity results in a greater concentration of nitrate in the lower stalk. However, the stalk nitrate-N concentration can be ...


Corn Stalk Nitrate Interpretation, John E. Sawyer Jul 2016

Corn Stalk Nitrate Interpretation, John E. Sawyer

John E. Sawyer

You’ve gotten results from corn stalk nitrate samples collected this fall. (Corn stalk nitrate analysis form.) Now, what do the results mean? The stalk nitrate test is based on the concentration of nitrate-N in the lower corn stalk (8 inch segment from 6 to 14 inches above the ground) when the plant reaches maturity (See Cornstalk testing to evaluate nitrogen management, PM 1584). In general, a larger amount of plant-available N in the soil during the time period before plant maturity results in a greater concentration of nitrate in the lower stalk. However, the stalk nitrate-N concentration can be ...


Anhydrous Ammonia Application And Dry Soils, John E. Sawyer Jul 2016

Anhydrous Ammonia Application And Dry Soils, John E. Sawyer

John E. Sawyer

It is almost time that anhydrous ammonia (NH3) applications could begin (remember 50 F and cooling 4-inch soil temperature). However, many soils in Iowa are quite dry this fall. So, can anhydrous ammonia be applied to dry soil? Will it be held in dry soil?


45th Annual North Central Extension-Industry Soil Fertility Conference, John E. Sawyer Jul 2016

45th Annual North Central Extension-Industry Soil Fertility Conference, John E. Sawyer

John E. Sawyer

If you would like to learn more about current soil fertility issues and research being conducted at universities across the North Central region, then consider attending the 45th Annual North Central Extension-Industry Soil Fertility Conference on November 4-5, 2015, from 1 p.m. to noon, at the Holiday Inn Airport in Des Moines, Iowa. The conference will include invited presentations from university and industry leaders, research reports from university soil fertility researchers, and posters outlining research by graduate students at universities across the North Central region (Illinois, Indiana, Iowa, Kansas, Kentucky, Michigan, Minnesota, Nebraska, North Dakota, Ohio, Ontario, Pennsylvania, South ...


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.


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 ...


Cold Temperatures And Burndown Herbicides, Robert G. Hartzler Apr 2016

Cold Temperatures And Burndown Herbicides, Robert G. Hartzler

Integrated Crop Management News

The weather forecast appears to be favorable for field activities so people will be anxious to get into the field. A concern for many will be the effect of the widespread freeze on the performance of burndown herbicides. Unfortunately, there is no simple blanket statement that can be made since the plant response will vary depending on weed species, weed size, and the herbicides used.


New Isu Research May Help Farmers Make More Informed Decisions About Land Use, Elke Brandes, Emily A. Heaton, Lisa A. Schulte-Moore, Fred Love Jan 2016

New Isu Research May Help Farmers Make More Informed Decisions About Land Use, Elke Brandes, Emily A. Heaton, Lisa A. Schulte-Moore, Fred Love

Integrated Crop Management News

A new study from a multidisciplinary team led by Iowa State University agronomists shows that significant portions of Iowa farmland consistently lose money and could influence many farmers to change how they use some of the acres they devote to corn and soybeans.