Northwest Iowa On-farm Research Soybean Yield Response to Headline Fungicide

Six years ago the Northwest Iowa On-Farm Research Project was started to cooperate with local farmers to compare crop production methods on a field scale size. Through this project, over 300 replicated comparisons have been done. Beginning in 2012, the Northwest Iowa On-Farm Research project will be recognized as a part of Iowa State University Farmer Assisted Research and Management (FARM) program. This program will also expand to southwest Iowa, north central Iowa, and central Iowa.

Yield Response of Planting Corn in Early April

Corn is planted earlier each year, which is one important component in maximizing grain yield. Earlier planting dates can be attributed to larger farms, less spring tillage, improvements in corn hybrids, improved drainage systems, and better seed treatments. Research conducted at the ISU Northwest Research Farm from 2006 through 2009 showed that the planting window for 98 percent or greater yield potential in northwest Iowa is April 15 to May 9. A 95 percent or greater yield potential can be realized from April 15 to May 18. A study was conducted from 2009 through 2011 at the Northwest Research Farm to determine how corn planted in early April compares with corn planted in the recommended planting window for the area.

Soybean Yield Response to Rhizobium Inoculation on Converted Grass Pasture

Much of the soybean plant's nitrogen requirement is supplied through nitrogen fixation when atmospheric nitrogen is converted into a usable form for the plant. Nitrogen fixation is critical for producing higher yield in soybean. For nitrogen fixation to occur, nitrogen-fixing bacteria (genus Rhizobium) need to be present in the soil. If soils do not already contain a high population of Rhizobium, these bacteria can be added either as a liquid or granular peat inoculant, or as a peat-based powder. The different forms can be seed applied or used in-furrow.

Seasonal and Rotational Influences on Corn Nitrogen Requirements

This project is 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.

Nitrogen Fertilization of Corn Grown with a Cover Crop

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 were 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 was 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.

Effectiveness of Foliar Fungicides by Timing on Hybrid Corn

Fungicides were rarely used on hybrid corn prior to 2007, however, in the past few years, some farmers have included fungicides in their common crop production, particularly as the value of grain has increased. Fungicides are recommended for foliar disease management to protect yield potential. There also have been reports of increased yields in the absence of disease. A number of fungicides are registered for use on corn. The objectives of this project were to evaluate the yield response of hybrid corn to foliar fungicide application at various timings.

Long-term Evaluation of Hybrid, Nitrogen, and Potassium Interactions in Continuous Corn

A long-term experiment was established in 2009 to study continuous corn responses to potassium (K), nitrogen (N), and hybrid rootworm resistance. Previous research suggested a need for this study. A long-term trial conducted until 2001 at the ISU Northern Research Farm showed that the maximum corn yield level and the N rate that maximized yield was higher when K was optimal or greater. In contrast, the relative yield response to N and the N rate that maximized yield were similar for soil-test phosphorus (P) levels ranging from very low to very high. Other studies have shown that rootworm resistance often increases yield compared with untreated susceptible hybrids. Also, that rootworm resistance does not consistently affect the K rate that maximizes yield, but increases K removal because of the higher yield levels. Therefore, this new study evaluates possible interactions between rootworm resistance and N and K fertilization in corn.

Seasonal and Rotational Influences on Corn Nitrogen Requirements

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.

Effectiveness of Foliar Fungicides by Timing on Hybrid Corn

Fungicide use on hybrid corn has increased considerably in the past four growing seasons primarily due to reports of increased yields, even in the absence of disease and higher corn prices. A number of fungicides are registered for use on corn. The objectives of this project were to 1) assess the effect of timing of application of fungicides on standability, 2) evaluate the yield response of hybrid corn to foliar fungicide application, and 3) to discern differences, if any, between fungicide products.

Soil and Plant Fertility Management for Soybeans

Producers utilizing a two year rotation of corn and soybean often apply fertilizer on a biannual basis, spreading recommended amounts of phosphorus and potassium for both crops prior to corn establishment. This approach minimizes application costs and is in accordance with university fertility recommendations that have found a low probability of fertilizer yield response when soils tested at the medium/optimum level or above. However, the field trials on which these state recommendations were developed are often several decades old. Increases in average corn and soybean yields and associated increases in crop nutrient removal rates have called into question the validity of these recommendations for current production environments. This study investigated the response of soil test levels and grain yield to annual and biannual fertilizer applications made at 1x and 2x rates of current university fertilizer recommendations.

Seasonal and Rotational Influences on Corn Nitrogen Requirements

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 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.

Effectiveness of Foliar Fungicides by Timing on Hybrid Corn in Iowa

Fungicide use on hybrid corn has increased considerably in the past three growing seasons primarily due to reports of increased yields, even in the absence of disease and higher corn prices. A number of fungicides are registered for use on corn. The objectives of this project were to 1) evaluate the yield response of hybrid corn to foliar fungicide application, 2) compare the yield response of various products and timing of application, and 3) to assess the effect of fungicide application on stalk rot development.

Effectiveness of Foliar Fungicides by Timing on Hybrid Corn

Fungicides were rarely used on hybrid corn prior to 2007, however, in the past few years some farmers have made fungicides a regular input in their crop production, particularly as the value of grain has increased. Fungicides are recommended for foliar disease management to protect yield potential. There have also been reports of increased yields in the absence of disease. A number of fungicides are registered for use on corn. The objectives of this project were to evaluate the yield response of hybrid corn to foliar fungicide application at various timings.

Seasonal and Rotational Influences on Corn Nitrogen Requirements

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.

Corn Response to Sulfur Application Rate

Historically, sulfur (S) application has not been recommended on Iowa soils for corn and soybean production. Soils supply, or a combination from sources such as soil organic matter, profile sulfate, manure, and precipitation have met crop S needs. However, over the past few years, S deficiencies in alfalfa and corn have been documented. Large crop yield responses have been measured in some fields containing soils with low organic matter, side-slope landscape position, or coarse soil texture, especially in northeastern Iowa. The objective of this study was to determine S response in corn and soybean in north-central Iowa.