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Articles 271 - 300 of 1479
Full-Text Articles in Life Sciences
Sulfur Fertilizer Application To Corn And Soybean, John E. Sawyer, Daniel W. Barker
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
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
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
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
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.
Post-Plant Nitrogen Applications On Corn, John E. Sawyer
Post-Plant Nitrogen Applications On Corn, John E. Sawyer
John E. Sawyer
Has the wet weather interrupted planned nitrogen (N) fertilizer applications? What are the options if corn has emerged? All is not lost. In fact, in wet springs sidedress N can be an advantage because delayed application avoids potential losses and increases use by the crop.
Potassium Deficiency Symptoms In Corn, John E. Sawyer
Potassium Deficiency Symptoms In Corn, John E. Sawyer
John E. Sawyer
The dry conditions this spring have resulted in corn plants expressing potassium (K) deficiency symptoms the past 2 weeks. This phenomenon has appeared in previous dry spring seasons and is back again this year, especially in southern Iowa. Areas of the state that received adequate rainfall are generally not showing K deficiency symptoms. Symptoms can appear even though soil K is adequate for crop production. How can this occur? Uptake of K by plants requires an active root system, especially in the soil zone where plant-available K is located.
Quantifying Corn N Deficiency And Application Rate With Active Canopy Sensors, Daniel W. Barker, John E. Sawyer
Quantifying Corn N Deficiency And Application Rate With Active Canopy Sensors, Daniel W. Barker, John E. Sawyer
John E. Sawyer
Precision agriculture technologies are an integral part of many operations in Iowa corn production. Active canopy sensors have been developed as a tool to determine plant N stress deficiency and provide on-the-go decisions for implementing variable rate N application. The objectives of this study were to assess N deficiency stress levels at the mid-vegetative corn growth stages with active canopy sensors, calibrate active sensors and associated canopy indices, and develop N rate algorithms that can be used to determine variable rate N fertilization.
Surface Waters: Ammonium Is Not Ammonia – Part 1, John E. Sawyer
Surface Waters: Ammonium Is Not Ammonia – Part 1, John E. Sawyer
John E. Sawyer
A recent article in The Des Moines Register newspaper has caused considerable controversy regarding nitrogen in Iowa streams and rivers. The article (High ammonia levels threaten D.M.’s water, April 6, 2008) featured information about “ammonia” levels in certain Iowa surface water systems during the recent winter time period. The implications were that manure and fertilizer application to cropland, and subsequent snowmelt and runoff, had resulted in higher than normal “ammonia” levels in surface waters. In the article there was a comparison of the reported levels to an ammonia reading of 0.10 parts per million considered harmful to aquatic life.
Postemergence Application Of Herbicides In Corn, Micheal D. Owen, John E. Sawyer, Robert G. Hartzler
Postemergence Application Of Herbicides In Corn, Micheal D. Owen, John E. Sawyer, Robert G. Hartzler
John E. Sawyer
The Iowa 2006 corn crop is mostly in the ground and much of it will be emerged by the end of the week. Planting progressed rapidly in late April prior to the current wet conditions, and this prolonged wet period will impact weed management plans for those fields planted prior to the rain but not treated with preemergence herbicides or nitrogen (N) fertilizer. This article is revised from a 2003 discussion and will describe two important issues.
Sulfur Fertilizer Application To Corn And Soybean, John E. Sawyer, Daniel W. Barker
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 may become depleted with prolonged crop removal, sulfate leaching, low precipitation deposition, and reduced soil organic matter levels. The objectives of this study were to determine if corn and soybean yields would respond to S fertilizer application and rate at sites in central and northeast Iowa.
Post Applied Urea+Agrotain To V10 Corn Field Scale Strip Demonstrations, Daniel W. Barker, John E. Sawyer
Post Applied Urea+Agrotain To V10 Corn Field Scale Strip Demonstrations, Daniel W. Barker, John E. Sawyer
John E. Sawyer
The objectives are to apply N fertilizer when corn rapidly accumulates N and dry matter during the mid-vegetative growth stages and utilize active sensors as a remote sensing method of applying VRT nitrogen.
Sulfur Fertilizer Application To Corn And Soybean, John E. Sawyer, Daniel W. Barker
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.
Surface Waters: Ammonium Is Not Ammonia – Part 2, John E. Sawyer
Surface Waters: Ammonium Is Not Ammonia – Part 2, John E. Sawyer
John E. Sawyer
A previous article explained the difference between ammonium and ammonia, the relationship between the two nitrogen forms and the implication of a combined (ammonium-N plus ammonia-N) analysis related to water quality criteria for aquatic life. This article focuses on the implication of ammonia and ammonium for chlorination of drinking water.
Sulfur Fertilizer Application To Corn And Soybean, John E. Sawyer, Daniel W. Barker
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
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
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
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 may become depleted with prolonged crop removal, sulfate leaching, low precipitation deposition, and reduced soil organic matter levels. The objectives of this study were to determine if corn and soybean yields would respond to S fertilizer application and rate at sites in central and northeast Iowa.
Nitrogen Fertilization Of Corn Grown With A Cover Crop, John E. Sawyer, Jose L. Pantoja, Daniel W. Barker
Nitrogen Fertilization Of Corn Grown With A Cover Crop, John E. Sawyer, Jose L. Pantoja, Daniel W. Barker
John E. Sawyer
Objectives of this project were to study corn nitrogen (N) fertilization requirement and corn-soybean yield response when grown in a cover crop system. Multiple rates of N fertilizer are applied, with measurement of corn yield response to applied N and soybean yield with and without a fall planted winter rye cover crop. The study is being conducted at several research farms, with the intent for study across multiple years to allow comparison of with and without a cover crop system across varying soil and climatic conditions.
Nitrogen Fertilization Of Corn Grown With A Cover Crop, John E. Sawyer, Jose L. Pantoja, Daniel W. Barker
Nitrogen Fertilization Of Corn Grown With A Cover Crop, John E. Sawyer, Jose L. Pantoja, Daniel W. Barker
John E. Sawyer
Objectives of this project were to study corn nitrogen (N) fertilization requirement and corn-soybean yield response when grown in a cover crop system. Multiple rates of N fertilizer are applied, with measurement of corn yield response to applied N and soybean yield with and without a fall planted winter rye cover crop. The study is being conducted at several research farms, with the intent for study across multiple years to allow comparison of with and without a cover crop system across varying soil and climatic conditions.
Nitrogen Fertilization Of Corn Grown With A Cover Crop, John E. Sawyer, Jose L. Pantoja, Daniel W. Barker
Nitrogen Fertilization Of Corn Grown With A Cover Crop, John E. Sawyer, Jose L. Pantoja, Daniel W. Barker
John E. Sawyer
Objectives of this project were to study corn nitrogen (N) fertilization requirement and corn-soybean yield response when grown in a rye cover cropping system. Multiple rates of N fertilizer are applied, with measurement of corn yield response to applied N and soybean yield with and without a fall planted winter rye cover crop. The study is being conducted at multiple research farms, with the intent for comparison of with and without a cover crop system across varying soil and climatic conditions in Iowa.
Nitrogen Fertilization Of Corn Grown With A Cover Crop, John E. Sawyer, Jose L. Pantoja, Daniel W. Barker
Nitrogen Fertilization Of Corn Grown With A Cover Crop, John E. Sawyer, Jose L. Pantoja, Daniel W. Barker
John E. Sawyer
Objectives of this project were to study corn nitrogen (N) fertilization requirement and corn-soybean yield response when grown in a rye cover cropping system. Multiple rates of N fertilizer are applied, with measurement of corn yield response to applied N and soybean yield with and without a fall planted winter rye cover crop. The study is being conducted at multiple research farms, with the intent for comparison of with and without a cover crop system across varying soil and climatic conditions in Iowa.
Nitrogen Fertilization Of Corn Grown With A Cover Crop, John E. Sawyer, Jose L. Pantoja, Daniel W. Barker
Nitrogen Fertilization Of Corn Grown With A Cover Crop, John E. Sawyer, Jose L. Pantoja, Daniel W. Barker
John E. Sawyer
Objectives of this project were to study corn nitrogen (N) fertilization requirement and corn-soybean yield response when grown in a rye cover cropping system. Multiple rates of N fertilizer are applied, with measurement of corn yield response to applied N and soybean yield with and without a fall planted winter rye cover crop. The study is being conducted at multiple research farms, with the intent for comparison of with and without a cover crop system across varying soil and climatic conditions in Iowa.
Natural Gas Prices Impact Nitrogen Fertilizer Costs, John E. Sawyer
Natural Gas Prices Impact Nitrogen Fertilizer Costs, John E. Sawyer
John E. Sawyer
Only 2 years ago nitrogen (N) fertilizer supply and price were impacted by a sharp rise in natural gas prices (winter 2000-2001). Another dramatic increase occurred within the past month. Natural gas prices have fluctuated more in recent years because of increased demand for generating electricity and slowed development of new gas supplies. This time, late-winter cold temperatures, high demand for home heating, and world unrest brought depleted supplies and uncertainties in production and pricing.
Making Fertilization Decisions As Fertilizer Prices Escalate And Production Costs Are High - Part 1, John E. Sawyer, Antonio P. Mallarino
Making Fertilization Decisions As Fertilizer Prices Escalate And Production Costs Are High - Part 1, John E. Sawyer, Antonio P. Mallarino
John E. Sawyer
Fertilizers are at unbelievably high prices, with reports of tight supplies and potash allocation to dealers. Total crop production costs are causing credit supply issues, which complicates decisions to allocate available funds for production expenses. These issues are causing producers to consider changing production practices, including cutting back on inputs like fertilizer. What can be done?
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.
Making Every Fertilizer Nitrogen Dollar Pay, John E. Sawyer
Making Every Fertilizer Nitrogen Dollar Pay, John E. Sawyer
John E. Sawyer
High fertilizer nitrogen (N) prices will add significant costs to corn production this year. Concurrently, spot shortages of some N products may occur. What steps can producers take to get the most return from added N? What are some options for managing fertilizer applications?
Is It Iron Or Potassium Deficiency?, John E. Sawyer
Is It Iron Or Potassium Deficiency?, John E. Sawyer
John E. Sawyer
Cool early summer temperatures have promoted symptom development of soybean iron chlorosis in some parts of Iowa, according to reports from Iowa State University field crop specialists and samples submitted to the Iowa State University Plant Disease Clinic. Yellowing soybean caused by iron chlorosis was a problem last growing season, and it may be a problem again for some growers this season.
Measuring The Nitrogen Status, John E. Sawyer
Measuring The Nitrogen Status, John E. Sawyer
John E. Sawyer
Tools are available that can aid decisions about applying supplemental nitrogen (N) when there have been losses of applied fertilizer or manure N. These can provide more site-specific information than estimating losses and can also provide N rate application guidance.
Nitrogen Fertilization Rates For Corn Production, John E. Sawyer
Nitrogen Fertilization Rates For Corn Production, John E. Sawyer
John E. Sawyer
October 13, 2014 – There has been a large change in corn grain prices this fall. How might that affect recommended nitrogen (N) fertilizer or manure-N application rates, and planning for the 2015 crop? The answer depends on more than just the price of corn, but also the price of nitrogen. It is the ratio of these prices (price ratio, where the $/lb actual N is divided by the $/bu corn; example, $0.50/lb N and $3.50/bu corn is a 0.14 price ratio). Both prices are important and influence recommended N rates as the ratio reflects the last unit of N …