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Corn+Soybean Digest

Focus on yield stressors to maximize return on crops

Focus on yield stressors to maximize return on crops
To make up for lower commodity prices, you might be tempted to emphasize spending on inputs across the board for top yields. Instead, consider a plan that funnels your focus and money into management decisions that target top yield stressors. 

Every crop input should be money well spent; every management action should be measured against its economic impact. This well-known advice is more important than ever with lower commodity prices this year.

However, selecting the specific actions to maximize economic return is the tough part. Where to begin?

Identify top yield stressors

“The whole idea of what you have to address and what you can afford to let go a little in tight economic times is a hot topic of discussion right now,” says Iowa State University cropping systems agronomist Mark Licht. “There’s no question farmers need to prioritize in tight times.”

Chad Lee, extension professor for grain crops at the University of Kentucky, agrees. “The last few years had enough profit margins that we tried all kinds of inputs in an attempt to maximize yield. We don’t have that luxury in 2015,” he says. “Getting an extra 5 bushels of yield this year may require the input cost of 15 bushels in some cases.”

This year, consider diverting management and money into identifying and reducing the top corn and soybean yield stressors.

Licht believes that weather and soil fertility issues are the two most imposing stressors on corn and soybean yields. “Weather causes more stress on crop yields than any other factor,” he says. “It’s also a factor in how serious all the other stressors are, because it influences every other stress, including fertility, weed competition, insect problems and diseases.”

Bob Nielsen, extension corn specialist and professor of agronomy at Purdue University, agrees. “You want to buffer the effects of stressful weather, and to do that you will want to identify and mitigate the other most yield-limiting factors in each field,” He says.


Adapt to variable weather

“It would be easy to say you can’t do anything about the weather,” Licht says. “But in truth, you can recognize weather patterns.”

The key, he says, is to make decisions based on current weather patterns, which are highly variable. To spread weather risks, he recommends the following:

Diversify maturity in corn selections. “Do this regardless of the weather forecast, because you can’t predict the weather that far out,” Licht says. “Having corn with a variety of maturation dates spreads out the risk of periods of extreme heat or precipitation and even killing fall frosts.”

Broaden out planting dates. “Be more cautious about being the first out to get corn planted,” Licht says. “Early vigor slows down in cold, wet soils, and cold temperatures affect germination rates.”

As workable field days in April and May are shrinking, broader planting dates extend opportunities to plant, apply fertilizer and apply weed control in-season.

“Avoid planting or tilling when soil conditions aren’t fit,” Nielsen says. “That’s usually when soils are too wet, when you can get shallow soil compaction or planter furrow compaction, both of which can later restrict initial root development in young corn.”

Make seeding rate decisions at planting time. “Moisture and temperature really play into seeding rates,” Licht says. Planting rates can be boosted in areas where topsoil is at field capacity but not saturated, and lowered in saturated soil and depressional areas. Seed company representatives can help select varieties that respond to conditions, he says.

Consider past yield response to plant populations, too. “Generally, if you have consistently seen corn kernels clear to the tip of the ear, you haven’t been seeding to capacity,” Licht says. “But if you see most ears with kernels tipped back about half an inch, you’ve got enough plants there.”

In the eastern Corn Belt, rainfall isn’t usually a limiting factor, so there’s less need to alter seeding rates. “Results from nearly 70 field-scale trials in Indiana in recent years clearly suggest final harvest populations in the low 30s are appropriate for the majority of the corn acres,” Nielsen says. For soils with low water holding capacity, he recommends final populations in the mid-20s.


Improve soil drainage and cut fertilizer risks

In the poorly drained soils of the eastern Corn Belt, installing tile drainage is the single most important management tool to reduce crop stress, Nielsen says. “Fields with no tile drainage or ancient tile drainage have high probabilities of stand failure and stunted crop development early in the growing season,” Nielsen says.

Cut fertilizer risks

There are economic risks from both applying too much and too little fertilizer. “Fertilizing to the soil test is financially more important this coming season,” Lee says. Licht has three fertility recommendations:

  • Put more focus on split N. With increasingly wet springs and early summers, there is a real risk of risk losing all the preplant nitrogen (N) you may have applied, Licht says. While there is a risk of not being able to get the N on as sidedress, if you are successful, you will get more N applied when the plant needs it and can reach yield goals with less nitrogen.
  • Don’t skimp on P and K. Rely on quality soil tests for phosphorus and potassium, Licht stresses. “It’s a high risk for lower yields if soil tests show these nutrient levels are low to very low.”
  • Cut back on yield tweakers. “In years of good return on investment, farmers have successfully used micronutrients, foliar fertilizers and other enhancements to tweak yields a bit higher,” Licht says. “But research has shown it can be challenging to get an economic yield response from these products, so it wouldn’t be a priority in lean years.”


Focus on residual weed control

Early weed control is critical for corn, Licht says. “You need to start with a good foundation for weed control, with residuals,” he says. “That early competition from weeds can hurt corn plants.” While soybeans can better compensate in yield, timing is still critical to effective weed control. “Overall, we just need to realize weeds will affect yields and we need to control them early,” Licht says.

“Spraying late robs yields, and letting weeds go this year causes problems in that field long term,” Lee adds. He also warns against deep tillage if there is no sign of compaction, and says light-tillage farmers to try no-till again this year. “No-till soils can gain an inch or two of stored water in the profile—if you’re in the southern Corn Belt, the mid-South or western Corn Belt where moisture is likely to be an issue, no-till could help.”


Be specific on insect and disease control

While insect and disease control does not his list of yield stressors, farmers need to be prepared to control them if they’ve shown up in the past, Licht says. “Soybean aphids have been a problem for some farmers, and you want to keep Japanese beetles on your radar. The key to this is scouting.”

Foliar diseases such as gray leaf spot and northern corn leaf blight are more common in the eastern Corn Belt, where humidity and rainfall are higher.

Licht recommends the following:

  • Use resistant hybrids. “Focus on using hybrids that are resistant to the insects or diseases you’ve had problems with in the past,” Licht says.
  • Jennifer Rees, Extension educator at the University of Nebraska, agrees. “Select the best corn hybrid and soybean variety for each piece of ground, based on disease and insect package and soil type/ground topography,” she says. “Use beginning soil moisture status in rain-fed fields to help determine plant population, and use split nitrogen applications, favoring more in the growing season when the plants need it. Then everything done at planting dictates the rest of the season.”
  • Plan to scout. Choose high-yield hybrids, be prepared to scout, and monitor media for early insect and disease alerts, Licht says.
  • “Frequent scouting of your fields should be an automatic part of your overall crop management strategy,” Nielsen says. “Today’s smartphone and tablet technologies offer the opportunity to electronically document scouting results and geo-tag specific problem areas so you can better determine cause and effect after harvest.”
  • Diversify crops. Move away from continuous corn, especially if you have insect or disease problems, Licht says. “If you don’t want to go to a corn-soybean rotation, consider using soybeans once every three years with corn.” Crop diversity in the rotation, including cover crops, is a good long-term strategy for profitability and stability, he advises.


Cover crops? It depends

Licht points to research showing that cover crops can reduce risk of yield losses in drought, sequester nitrogen and, with good management, can reduce disease and insect impact and the need for some crop inputs. “But I’ve also seen reduced yields along with the extra cost of seeding and terminating them,” he says. “For newcomers to the practice, cover crops might be a risk they don’t need in times of tight margins.”

For newcomers to the practice, Licht suggests first trying cover crops that winter kill. Otherwise, “If there’s not a direct return in a tight margin year, and a need for a higher level of management, I have a harder time recommending it for them this year.”

TAGS: Soybeans
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