2026 September Stewardship Advocate

2026 September Stewardship Advocate

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Fall Season and El Niño

State Climatologist Dr. Justin Glisan has flagged that a very strong El Niño event is shaping up in the Pacific Ocean. Historically, these above-average ocean temperatures have brought warmer and generally wetter weather to Iowa in the fall, which could create less-than-ideal conditions this harvest season.

Iowa State University recommends waiting until the 4-inch soil temperature is at least 50°F and falling to apply manure and anhydrous ammonia. Following fall nutrient application best practices will be especially important with the conditions that could set up this year. Because of the warmer, wetter weather that may occur, the date when Iowa fields reach 50 and falling could be 10-15 days later than usual. For example, Central Iowa typically hits 50 and falling around Nov. 10, but it could be closer to Thanksgiving this year.

Iowa State University Extension and Outreach has issued the following fertilizer application guidance: Fifty and Falling: What the Super El Niño Means for Anhydrous Ammonia and Manure Timing this Fall

Some key takeaways:

1. Monitor soil temperatures rather than calendar dates.
2. Use nitrification inhibitors with ammonia and manure nitrogen sources.
3. Consider planting a cover crop, particularly on fields going to soybeans.
4. If manure is applied early, it should be on a field with a cover crop that can reduce nitrate runoff to waterways.
5. Warm soils can increase nitrogen mineralization. Use precision tools, like fall N soil sampling and N-FACT, to inform and optimize application rates.

Good adaptive nitrogen and manure management practices are important every year, but they may be especially impactful for profitability, productivity and environmental stewardship this fall.

Preparing for Corn Harvest

Harvest season is the culmination of everything that has happened since before planting and when the combines hit the fields in the fall. Iowa State University agronomists and others have a number of tips as you prepare for harvest. These include field checks, equipment preparation, storage considerations, and post-harvest management decisions.

Field Scouting and Standability

• Scout for Stalk Quality: Check fields for stalk rot, foliar diseases (such as gray leaf spot or tar spot), and ear molds and prepare to harvest these fields first. The stalk "pinch" test and stalk "push" test are tools to check for the stalk quality in your fields and are described in Table 1.

Table 1. Pinch and push tests to determine stalk integrity. Source: ISU Stalk Rot Tests

• Prioritize Stressed Fields: Prioritize fields that experienced hail, wind damage, or severe weather stress during the season, as these are more prone to lodging and stalk deterioration.

• Assess Insect Damage: Open husks to check for late-season insect feeding and diseased kernels, which can encourage ear mold development and reduce overall grain quality.

Equipment and Combine Preparation

• Combine Settings and Efficiency: Follow manufacturers recommendations to maximize your combine's efficiency.

• Fire Safety: Be vigilant about machinery maintenance. Moving parts and hot bearings present a serious field fire risk during dry stretch runs in the fall. Have a fire extinguisher on the combine.

Moisture and Storage Targets

• Target Moisture Levels: Ensure long-term storable corn is dried down safely below 15% moisture before placing in longer term storage or prepare for commercial elevator delivery where higher moisture levels incur steep grade discounts.

Cover Crop Seeding

• Ensure that your cover seed is ordered and decide when, where and how you will plant cover crops before, during or after corn harvest.

• Apply for cover crop seed cost share programs to reduce the cost of cover crops seed and planting. Consult the Conservation Compass at https://www.iaagwater.org/conservation-compass/ to compare incentives for cover crops and other conservation practices.

Residue Management

• Have a plan to address cornstalks during or after harvest. Options include baling, chopping, using microbial break-down products, or incorporating the stalks. Perhaps you are fine with not touching the field after harvest and wait till the next spring.

Corn harvest includes many factors and decisions. Being prepared to prioritize fields may be the most important decision you make in the fall.

Latest Information

Secretary Naig Announces Record Cover Crop Cost-Share Signup

Secretary Naig and INREC Expand Nitrogen Soil Sampling

ProjectUSDA Invests up to $310 Million in Partnership Projects to Boost Farm Operations and Conserve Natural Resources

Eric Weuve and his parents Wayne and Cathy farm in Story County near the towns of McCallsburg and Zearing. Eric returned to the farm in 2013 which his parents have farmed since 1973.

The Weuves have a 50-50 corn-soybean rotation and have grown seed corn in the past. They are now strictly row crop producers without the livestock they had at one time.

Eric says one of his farming goals is to expand their acres, saying, "I am fortunate that I have off-farm income so that allows me to reinvest all profits back into my operation. As dad and I continue to plan the full transition for his retirement, it will be good to have that flexibility. Since returning to the operation, we have continued to focus on reducing tillage where possible with retaining as much residue cover as possible while doing enough tillage to alleviate the compaction that a lot of our soils are prone to."

He continues, "The next generation of my family is limited and not likely to continue farming. Identifying a first-generation farmer to assist in entering production agriculture is a long-term goal of mine while maintaining our land as a supplemental income stream for our family members. Being a farmer goes back multiple generations on both sides of my family. That legacy is important to me."

Eric's corn production consists of planting 106-113-day hybrids at 33,600 to 36,800 seeds per acre. The early corn goes in places where drying options are limited, and/or the corn is going to town. The corn going into on-farm storage is 109 to 113 RM to obtain the full-season benefit.

Eric relies on variable rate applications of nitrogen, phosphorus, potassium, and sulfur. He says, "We switched to variable rate applications a few years ago from a two-year program going into corn. While yield goals are a driving factor, I believe we out-produced on corn yield, consuming the nutrients that were intended for the following soybean crop. This also allows us to adapt to yield and other factors annually. For nitrogen, we have long used 32% Urea Ammonium Nitrate. We have side dressed in the early summer for about 20 years. About 10 years ago, we switched to applying a base rate of about 50 pounds on nitrogen per acre as preplant, and then variable rating the majority of the field needs as a side dress. This year, we had a nitrogen use efficiency rate, depending on the field, of 0.7 to 0.9 pounds of nitrogen per expected bushel of production. With the nitrogen price where it has been the last several years, managing nitrogen use and efficiency has been a major decision factor for us."

When asked about what changes he made in 2026, Eric says, "I spent a lot of time with my fertilizer prescription agronomist trying to balance economics and environmental needs along with building fertility where it made sense. Looking ahead, I would like to incorporate starter fertilizer into our operation."

In addition to farming and his off-farm job, Eric takes time to give back to his fellow farmers and to the corn industry. He says, "I am a District 5 Iowa Corn Promotion Board Director. This past year, I was on the Exports and Grain Trade Committee and will be on the Usage and Production Committee this coming year. I serve on Iowa Corn to be an advocate for our industry and my neighbors. Our corn industry needs strong leaders to share their viewpoints and knowledge to improve practices that work for everyone. Production agriculture is near and dear to my heart, and I want to ensure that it is still a viable and growing industry for future generations."

In closing, Eric says, "Every farm that we farm is different whether it requires a different fertility program, tillage practices etc. and I strive to manage them as individual farms and not treat every acre the same."

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