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Articles 1 - 27 of 27
Full-Text Articles in Physical Sciences and Mathematics
Mapping Temperate Vegetation Climate Adaptation Variability Using Normalized Land Surface Phenology, Liang Liang, Mark D. Schwartz, Xiaoyang Zhang
Mapping Temperate Vegetation Climate Adaptation Variability Using Normalized Land Surface Phenology, Liang Liang, Mark D. Schwartz, Xiaoyang Zhang
Xiaoyang Zhang
Climate influences geographic differences of vegetation phenology through both contemporary and historical variability. The latter effect is embodied in vegetation heterogeneity underlain by spatially varied genotype and species compositions tied to climatic adaptation. Such long-term climatic effects are difficult to map and therefore often neglected in evaluating spatially explicit phenological responses to climate change. In this study we demonstrate a way to indirectly infer the portion of land surface phenology variation that is potentially contributed by underlying genotypic differences across space. The method undertaken normalized remotely sensed vegetation start-of-season (or greenup onset) with a cloned plants-based phenological model. As the …
The Illinois Soil Nitrogen Test: Should It Be Used In Iowa?, John E. Sawyer, Mohammod Ali Tabatabai
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
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
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
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
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
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
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
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).
Evaluation Of Fertilizer Additives For Enhanced Nitrogen Efficiency In Corn, Daniel W. Barker, John E. Sawyer, Michael J. Castellano
Evaluation Of Fertilizer Additives For Enhanced Nitrogen Efficiency In Corn, Daniel W. Barker, John E. Sawyer, Michael J. Castellano
John E. Sawyer
The use of N additives and slow release materials with ammoniacal fertilizer varies throughout the U.S. Corn Belt due to differing N loss potentials across climate, soils, and production systems. In Iowa, recent years of high rainfall events and prolonged wet soil conditions has renewed interest to protect fertilizer N loss from denitrification, leaching, and greenhouse gas emission with use of nitrification inhibitors. These loss processes can be significant in Iowa soils that are poorly drained and have high organic matter, high pH, and high populations of denitrifying bacteria. Subsurface tile drainage is also prevalent in farmer fields throughout the …
Drought Impacts On Soil Fertility Management, John E. Sawyer
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
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 …
Corn Stalk Nitrate Interpretation, John E. Sawyer
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 greatly …
Comparing The Fieldscout Greenindex+ Chlorophyll Sensing App To The Minolta Spad Meter, Jessica D. Pille, John E. Sawyer, Daniel W. Barker
Comparing The Fieldscout Greenindex+ Chlorophyll Sensing App To The Minolta Spad Meter, Jessica D. Pille, John E. Sawyer, Daniel W. Barker
John E. Sawyer
With the improvement of mobile computing, the company Spectrum Technologies, Inc. has developed a precision Ag App which adapts an iPod, iPad, or iPhone camera to select for specific wavelengths of light from a corn leaf (Zea mays L.) in comparison to accompanying board for light/color comparison. The App computes a Dark Green Color Index (DGCI), indicating leaf greenness, which relates to the amount of chlorophyll and thus, indirectly, leaf nitrogen (N) content. The question posed for this study is: How accurate and convenient is the App compared to a proven technology, the Minolta 502 Soil-Plant Analysis Development (SPAD) meter; …
Anhydrous Ammonia Application And Dry Soils, John E. Sawyer
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
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 Dakota, …
Sulfur Management For Iowa Crop Production, John E. Sawyer, Brian J. Lang, Daniel W. Barker
Sulfur Management For Iowa Crop Production, John E. Sawyer, Brian J. Lang, Daniel W. Barker
John E. Sawyer
Summary of statewide evaluation in Iowa of alfalfa and corn yield response to applied sulfur fertilizers. On-farm, small-plot and field-length strip trial yield response data presented from 2005-2013.
Interpretation Of Soil Test Results, Antonio P. Mallarino, John E. Sawyer
Interpretation Of Soil Test Results, Antonio P. Mallarino, John E. Sawyer
John E. Sawyer
A detailed explanation on how to interpret soil test results to assist with soil nutrient recommendations.
A General Guide For Crop Nutrient And Limestone Recommendations In Iowa, Antonio P. Mallarino, John E. Sawyer, Stephen K. Barnhart
A General Guide For Crop Nutrient And Limestone Recommendations In Iowa, Antonio P. Mallarino, John E. Sawyer, Stephen K. Barnhart
John E. Sawyer
Find phosphorus and potassium recommendations, micronutrient recommendations, and limestone recommendations for soils.
Also find soil test procedures and categories.
Nutrient Considerations With Corn Stover Harvest, John E. Sawyer, Antonio P. Mallarino
Nutrient Considerations With Corn Stover Harvest, John E. Sawyer, Antonio P. Mallarino
John E. Sawyer
Weigh the relationships between corn stover harvest (as compared to grain only harvest) with the research presented in this publication.Make informed decisions about using stover harvest for bioenergy and using corn residue for soil sustainability. Find corn N, P, and K fertilization recommendations needed to maintain desirable soil-test values.
Impacts Of Cover Crops On Phosphorus And Nitrogen Loss With Surface Runoff, Antonio Mallarino, Richard Cruse, Dan Jaynes, John Sawyer, Pablo Barbieri
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
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.
Implications Of Changes (Structural And Market) On Farm Management And Marketing Research, George R. Allen, Lester S. Kellogg, G. Edward Schuh, Vernon W. Pherson, Reynold P. Dahl, Rex F. Daly, Dale E. Hathaway, Neil E. Harl, Earl O. Heady, A. Gordon Ball, Glenn L. Johnson, Dale O. Anderson, Lowell D. Hill, John C. Redman, Robert W. Rudd, B. F. Jones, A. Allen Schmid, Karl A. Fox, George D. Irwin, R. L. Kohls, John E. Lee Jr., Thomas T. Stout
Implications Of Changes (Structural And Market) On Farm Management And Marketing Research, George R. Allen, Lester S. Kellogg, G. Edward Schuh, Vernon W. Pherson, Reynold P. Dahl, Rex F. Daly, Dale E. Hathaway, Neil E. Harl, Earl O. Heady, A. Gordon Ball, Glenn L. Johnson, Dale O. Anderson, Lowell D. Hill, John C. Redman, Robert W. Rudd, B. F. Jones, A. Allen Schmid, Karl A. Fox, George D. Irwin, R. L. Kohls, John E. Lee Jr., Thomas T. Stout
Neil E. Harl
This conference was really an outgrowth of an earlier conference on Structural Changes in Commercial Agriculture (CAED Report 24) held in Chicago, April 12-14, 1965. While the earlier conference emphasized structural changes in the agricultural industry and their implications for education and extension, the 1967 conference focused on research.
Adjusting Hail-Damaged Crops For Crop Insurance Reporting, William M. Edwards
Adjusting Hail-Damaged Crops For Crop Insurance Reporting, William M. Edwards
William Edwards
Hail damage to crops in north central Iowa caused great losses; the total of which will become more defined with harvest. The following guidelines are intended to help farmers through the process of adjusting hail-damaged crops for crop insurance reporting.
Adjusting Hail-Damaged Crops For Crop Insurance Reporting, William M. Edwards
Adjusting Hail-Damaged Crops For Crop Insurance Reporting, William M. Edwards
William Edwards
Hail damage to crops in north central Iowa caused great losses; the total of which will become more defined with harvest. The following guidelines are intended to help farmers through the process of adjusting hail-damaged crops for crop insurance reporting.
Adjusting Hail-Damaged Crops For Crop Insurance Reporting, William M. Edwards
Adjusting Hail-Damaged Crops For Crop Insurance Reporting, William M. Edwards
William Edwards
Hail damage to crops in north central Iowa caused great losses; the total of which will become more defined with harvest. The following guidelines are intended to help farmers through the process of adjusting hail-damaged crops for crop insurance reporting.
Adjusting Hail-Damaged Crops For Crop Insurance Reporting, William M. Edwards
Adjusting Hail-Damaged Crops For Crop Insurance Reporting, William M. Edwards
William Edwards
Hail damage to crops in north central Iowa caused great losses; the total of which will become more defined with harvest. The following guidelines are intended to help farmers through the process of adjusting hail-damaged crops for crop insurance reporting.