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10/15/2012 - 10/21/2012

Farmers Reminded to Wait Until Soil Temps are 50 Degrees and Falling Before Applying Anhydrous Ammonia Fertilizer

Farmers are encouraged to wait until soil temperatures remain below 50 degrees Fahrenheit before applying anhydrous ammonia (NH3) fertilizer this fall. With the record early harvest this year, officials with the Iowa Department of Agriculture and Land Stewardship and Iowa State University (ISU) Extension and Outreach said that waiting can help reduce nitrogen loss and better protects the environment.
“With farmers finishing harvest earlier than normal, it is important that they still wait for cooler soil temps to apply anhydrous so that there is a better chance the fertilizer stays put and will be available to the crop next spring,” said Bill Northey, Iowa Secretary of Agriculture.  “Soil temperatures, like air temperatures, can change quickly so it is important that we wait with applications until soils are likely to remain below 50 degrees.”

“Historically, soil temperatures at a 4-inch depth cool below 50 degrees in the northern third of the state during the first week of November,” said Elwynn Taylor, ISU Extension and Outreach climatologist. “In central and southern Iowa, soil temperatures cool below 50 degrees during the second and third weeks of November.”
ISU Extension and Outreach maintains a statewide real-time soil temperature data map on their website that ag retailers and farmers use to determine when fall N applications are appropriate. The website can be found at
Farmers should also be mindful to pay special attention when applying anhydrous ammonia to very dry soil. Dry soil can hold ammonia, but if they are cloddy and do not seal properly, the ammonia can be lost at injection or seep through the large pores between clods after application.
So farmers and applicators should assure proper depth of injection and good soil coverage when applying into dry soils. If, following a round of application in the field, the ammonia can still be smelled, the applicator should make adjustments or wait for better conditions.

Hundreds of SCN-resistant Soybean Varieties Available for 2013

Profitable soybean yields can be produced in fields infested with the soybean cyst nematode (SCN) by growing SCN-resistant soybean varieties. SCN-resistant soybeans can keep SCN population densities from increasing and produce high yields.

Each year, Iowa State University compiles a list of SCN-resistant soybean varieties that are available to Iowa soybean farmers for the upcoming growing season. The list is published with support from the Iowa Soybean Association. The updated version of the publication, titled “Soybean cyst nematode-resistant soybean varieties for Iowa,” is now available for use in planning the 2013 soybean crop.


Slightly fewer varieties for 2013, almost all with PI 88788 SCN resistance

The publication contains information about 155 SCN-resistant soybean varieties in maturity groups 0 and 1, 325 varieties in group 2 and 291 varieties in group 3. Only 15 of the 771 varieties, or 2 percent, have resistance from a source other than the common PI 88788 breeding line. There are 34 fewer varieties (see Figure 1) and two fewer companies represented in the list compared to last year’s list.

Most of the varieties in the list are glyphosate resistant. Some have LibertyLink® herbicide resistance.  And 63 varieties, or 8 percent, are neither glyphosate resistant nor LibertyLink®.

Figure 1. Number of SCN-resistant soybean varieties available to Iowa soybean growers from 1991 to 2012. The red portion of each bar represents the number of varieties with SCN resistance from a source other than PI 88788.


Many ISU varieties in the list

There are 21 SCN-resistant soybean varieties in the publication that were developed by Iowa State University scientists with soybean checkoff funding from the Iowa Soybean Association. Of particular note is variety “IAR3001 Phyto SCN,” which has SCN resistance from PI438489B and PI90363; this is the only maturity group 3 soybean variety in the list with SCN resistance from a source other than PI 88788.


Publication available online and in print

The list of SCN-resistant soybean varieties for 2013 is available in PDF format online at the Iowa Soybean Association Production Research web site. Print copies of the publication will be available for purchase from the ISU Extension Online Store (PM 1649) by the end of October.


Greg Tylka is a professor with extension and research responsibilities in management of plant-parasitic nematode in the Department of Plant Pathology and Microbiology at Iowa State University. He can be reached at or 515-294-3021.


Integrated Crop Management Conference Set for November 28-29

By Alison Robertson, Department of Plant Pathology and Microbiology, and Brent Pringnitz, Ag and Natural Resources


The Iowa State University (ISU) Integrated Crop Management Conference will be held Nov. 28 and 29 on the ISU campus. Registration begins at 7:30 am on Nov. 28 in the Scheman Continuing Education Building, and the program concludes at 4:00 pm on Nov 29.

Conference attendees can choose from 40 different workshops that offer the latest information on crop production and protection technology in Iowa and surrounding states. Workshops are offered by ISU faculty and staff and invited speakers from around the Midwest. The Conference is hosted by ISU Extension and Outreach, the College of Agriculture and Life Sciences and the departments of Agricultural and Biosystems Engineering, Agronomy, Economics, Entomology, and Plant Pathology and Microbiology.

A popular feature of the conference is the variety of guest speakers on the program. “Each year ISU specialists invite colleagues in their field to share their research activities with conference attendees. This provides an opportunity to hear expertise and opinions from across the region and country in one location,” said Alison Robertson, Extension plant pathologist and chair of the planning committee. “This year we have 11 visiting presenters representing five states, sharing information on soil fertility, crop diseases, weed management and soil conservation. It’s a great program this year.”

In addition to the traditional topics, this year’s program will include three mini-symposia that each focus on a specific area of interest: production of corn stover for ethanol, sustainable biofuel production using perennial plants, and soil and water conservation to support and sustain soil quality.

In recent years, the conference has filled to capacity with nearly 1,000 producers and agribusiness representatives in attendance. “The conference is fortunate to have a loyal following of people that attend each year. While filling to capacity is a good problem to have, we hate to turn people away. We encourage people to register early,” states Brent Pringnitz, conference coordinator for ISU Extension. Attendees can obtain Certified Crop Adviser credits as well as recertification for Commercial Pesticide Applicators in categories 1A, 1B, 1C, 4 and 10.

To register online or for more information, visit the conference website at Registration is $185. After Nov. 16, registration increases to $235. Enrollment is limited and no registrations will be accepted at the door. Be sure to register early to guarantee your spot at this event! 


Alison Robertson is an Extension plant pathologist. she can be reached at (515) 294-6708 or e-mail Brent Pringnitz is a program services coordinator. He can be reached at (515) 294-6429 or e-mail

This article was published originally on 10/22/2012 The information contained within the article may or may not be up to date depending on when you are accessing the information.

Links to this material are strongly encouraged. This article may be republished without further permission if it is published as written and includes credit to the author, Integrated Crop Management News and Iowa State University Extension. Prior permission from the author is required if this article is republished in any other manner.