Researchers from Washington and Connecticut are seeking to improve corn nitrogen (N) recommendations to the point that recommendations can be made on a field-by-field basis.

The two most common current corn N recommendation methods are the Yield Goal Method and the Maximum Return to Nitrogen (MRTN) method—the method currently used by Michigan State University Extension. These methods are good for achieving profitable yields, on average, across many fields and years, but they are not suited—or intended—for field-specific recommendations.

In “Factors Affecting Nitrogen Availability and Variability in Cornfields,” published Aug. 16, 2018, in the Agronomy Journal, the researchers noted the promotion of the “4Rs of Nutrient Stewardship” concept: right source, right rate, right time and right place.

To develop this model, the researchers used aerial imagery and digital soil maps to guide cornstalk sampling for the Cornstalk Nitrate Test (CSNT)—a reliable end-of-season evaluation tool for corn N status. The researchers started with a two-year study conducted on 683 fields in Iowa, and expanded it to include 920 more fields in Illinois, Indiana, Ohio and Michigan from 2008 to 2014.

The researchers took aerial imagery of these fields in mid- to late August each year. Guided by USDA-NRCS digital soil maps, and aerial imagery, the researchers selected four sampling areas in each of the 920 fields for a total of 3,680 cornstalk sampling sites. The researchers identified three predominant soil types in each field.

Almost half (43 percent) of the fields in the study received N rates between 150–200 pounds per acre, and 78 percent of fields received N rates between 150–250 pounds per acre. Most farmers applied N as a sidedress between V3 and V6 in the form of anhydrous ammonia (24 percent) or urea ammonium nitrate (43 percent). About 19 percent of fields received a fall application of anhydrous ammonia, and the remainder of the fields received spring anhydrous (6 percent) or UAN (8 percent).

Most of the fields were managed as soybean-corn rotations, some were corn-corn and others were wheat-corn. Seventy-six percent of the fields were tilled using strip tillage or chisel tillage in the spring or fall, and 24 percent were no-till.

Ultimately, the researchers learned that three types of factors had significant effects on N sufficiency levels.

To find out what he three factors were and the effects on N sufficiency levels, check out the story from Michigan State University here. 

Wondering how to incorporate conservation practices into your next lease? Or are you a landowner wondering how you could start a conservation with the producer about conservation? Check out these tips.

The first step to take is for both parties to meet and have an open discussion about the goals of including specific practices. Specific practices such as wanting a tenant to include a cover crop on crop acres takes planning in advance, maybe up to a year in advance. A conversation about who is paying for the seed and the seeding of the cover crop, termination costs, possible decrease in commodity crop yields and other factors should be included in the discussion. Other practices such as moving from conventional tillage to strip-tillage or no-tillage may require a significant investment on the part of the tenant in terms of machinery. In either case, these annual practices may require a huge learning and adoption curve so expectations from both parties need to be understood and discussed. Starting on a small number of acres is highly advisable.

More permanent practices such as waterways and terraces are likely to benefit the landowner long- term more than the tenant and may be a cost the landowner incurs. Management and maintenance by the tenant may be required so including language in the lease can be specific to the situation. There are many conservation practices available that address soil erosion, water quality and wildlife benefits, but for the purpose of this article let’s focus on cover crops.

Cover crops are loosely defined as closely planted crops that bridge the gap between harvest and planting of our primary commodity crops such as corn and soybean. During this time much of Iowa’s landscape is bare of vegetation and is most vulnerable to water and wind erosion as well as nutrient loss. Cover crops are planted for many reasons including but not limited to, 1) reduce erosion, 2) cycle nutrients such as nitrogen that could otherwise be lost to leaching, 3) improve soil health and 4) feed source for animals. If a landowner or tenant is considering cover crops to meet any of the above reasons here is a list of things to consider and ways to start the conversation.

For more tips, check out, this story from Iowa State University. 

Waterhemp is becoming the most concerning weed in row crop production in Wisconsin.  Wisconsin farmers and agronomists are encouraged to collect waterhemp seeds this fall from their row crop production fields and submit them to UW-Madison for herbicide resistance screenings (we ask farmers to collect samples from only one of their fields; preferably the one with the most troublesome infestation level).

We intend to screen samples in the greenhouse for resistance to glyphosate (Group 9) and also to PPO-inhibitor (e.g., Cobra, Flextar, Cadet; Group 14), ALS-inhibitor (e.g., Pursuit, Classic, FirstRate; Group 2), HPPD-Inhibitor (e.g., Callisto; Group 27), PSII-inhibitor (e.g., Atrazine; Group 5) and Growth Regulator (e.g., dicamba, 2,4-D; Group 4) herbicides. Results will be made available to those who submit the samples after the greenhouse screenings are completed.

There is no cost associated to the herbicide resistance screening. The only cost will be your time to collect the seed samples and mailing them to: Rodrigo Werle, 1575 Linden Drive, Madison, WI 53706.

Download and print the SEED COLLECTION FORM (PDF file) for information on how to collect the seeds and fill out the information necessary for the project. Please submit the form with the seed sample. Samples will only be included in the herbicide resistance screening if the information requested herein is provided by the farmer/agronomist.

For questions, contact Dr. Rodrigo Werle via e-mail: rwerle@wisc.edu or phone: 608-262-7130.

As the weekend approaches, it's time for all of us to take a deep breath and have a good giggle. We hope you enjoy the Labor Day weekend!