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Full-Text Articles in Physical Sciences and Mathematics

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 ...


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 ...


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 ...


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.


Potassium And Sulfur Availability And Lime Potential Of Ash Co-Product Of Corn Cellulosic Ethanol Processing, Samuel Groenenboom Jan 2016

Potassium And Sulfur Availability And Lime Potential Of Ash Co-Product Of Corn Cellulosic Ethanol Processing, Samuel Groenenboom

Graduate Theses and Dissertations

Lignin-derived ash obtained as a co-product of corn residue used for ethanol production may have value as a soil amendment. Preliminary laboratory analyses indicated that the ash had potential lime value and higher concentrations of K and S compared with other nutrients. The value of the ash to supply K and S and to increase soil pH was evaluated at two Iowa sites compared with commonly applied sources of K (KCl) and S (gypsum) and pure CaCO3. At each site, three 2-year trials were initiated to assess the K, S, and lime values of the ash. Several rates of each ...


Inaugural Iowa Soil Health Conference Coming In February 2016, Mahdi Al-Kaisi Oct 2015

Inaugural Iowa Soil Health Conference Coming In February 2016, Mahdi Al-Kaisi

Integrated Crop Management News

The Inaugural Soil Health Conference, “Strategies for Building Healthy Soils” will be February 2-3, 2016 at the Scheman Building in Ames, Iowa. The conference is a collaborative effort between Iowa State University Extension and Outreach, Iowa State University College of Agriculture and Life Sciences and the United States Department of Agriculture Natural Resource Conservation Service. The goal of this conference is to increase awareness and understanding of soil health as a pivotal measure to sustainable agriculture and environmental quality in Iowa.


45th Annual North Central Extension-Industry Soil Fertility Conference, John E. Sawyer Oct 2015

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

Integrated Crop Management News

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 ...


Conceptual And Scaling Evaluation Of Vehicle Traffic Thermal Effects On Snow/Ice-Covered Roads, Joseph M. Prusa, Moti Segal, Bradley R. Temeyer, William A. Gallus Jr., Eugene S. Takle Sep 2015

Conceptual And Scaling Evaluation Of Vehicle Traffic Thermal Effects On Snow/Ice-Covered Roads, Joseph M. Prusa, Moti Segal, Bradley R. Temeyer, William A. Gallus Jr., Eugene S. Takle

William A. Gallus Jr.

The potential thermal effects of traffic on road surface thermal energy balance under frost/snow cover conditions have been largely ignored in meteorological evaluations of road ice deposit conditions. Preliminary exploration of these effects, particularly for heavy traffic scenarios with calm wind conditions and an ambient temperature of 0°C, is provided in this study using a conceptual model. Observational data were used to constrain the model, and parameterizations were employed to estimate the various heat transfer processes involved. The results indicate that, for heavy traffic situations, as well as for stopped traffic at intersections, the traffic thermal flux contribution ...


In-Season Corn And Soybean Forecast Of Soil Water-Nitrogen And Yields For Central And Northwest Iowa: A Pilot Project, Sotirios Archontoulis, Mark A. Licht, Ranae N. Dietzel Jun 2015

In-Season Corn And Soybean Forecast Of Soil Water-Nitrogen And Yields For Central And Northwest Iowa: A Pilot Project, Sotirios Archontoulis, Mark A. Licht, Ranae N. Dietzel

Integrated Crop Management News

A team of Iowa State University Department of Agronomy faculty and staff specialists in crops, soils and climate have begun an innovative pilot project to provide an in-season crop and soil water-nitrogen status and an end-of-season yield forecast. The approach combines use of the Agricultural Production Systems sIMulator (APSIM) cropping systems model, the Weather Research and Forecast Model (WRF), and parallel in-field data collection to verify model predictions.


Nitrogen Issues So Far This Spring, John E. Sawyer Jun 2015

Nitrogen Issues So Far This Spring, John E. Sawyer

Integrated Crop Management News

Across the state, generally there has not been excessive precipitation and much of Iowa has been below normal the past 60 days. A few areas have received more than normal precipitation, mostly in western to southwestern Iowa, some isolated areas in central to north central Iowa, and very eastern Iowa (see map).


A Hydroclimatic Assessment Of The U.S. Corn Belt Across Spatial And Temporal Scales, Olivia B. Kellner Apr 2015

A Hydroclimatic Assessment Of The U.S. Corn Belt Across Spatial And Temporal Scales, Olivia B. Kellner

Open Access Dissertations

The term hydroclimate is used to describe the climate of a given location as determined by the incident radiant energy (temperature) and the existence of water in its various forms on Earth. Two types of climate comprise the science of hydroclimatology: the climate as established by general global circulation patterns at specific locations on Earth (large-scale climate) and the climate established at Earth's surface resulting from the daily fluxes of radiant energy and water in its various forms between the atmosphere, Earth's surface, and the subsurface (local-scale climate) (Shelton 2009). This dissertation investigates different spatial and temporal scales ...


Starter Fertilization Sometimes Boosts Corn Yield, Antonio P. Mallarino Mar 2015

Starter Fertilization Sometimes Boosts Corn Yield, Antonio P. Mallarino

Integrated Crop Management News

Starter fertilizer can be used to complement pre-plant fertilization of crops to increase yield and economic returns to production. However, its use will not be beneficial in all production conditions.