Agronomy 101 — Corn
Fertility and hybrid selection
Extension specialists agree on the necessity of knowing your soil’s nutrient content. Just as you wouldn’t haphazardly choose a hybrid, neither should you plant that hybrid in soils that lack the fertility to help it reach its yield potential.
“Don’t start the year without grid sampling your fields,” advises Dr. Dan Fromme, associate professor and state corn specialist at the LSU AgCenter. “If you can’t afford to apply everything soil test results recommend, apply what you can afford.”
Corn is not a forgiving crop when nutrient levels are inadequate, and winter is a good time to figure out which nutrients are limiting factors. Lime should be spread as early as possible after harvest to allow time for it to neutralize acidic soils.
“I also tell my farmers not to get caught with too many things to take care of when planters start rolling,” says Dr. Angela McClure, professor and Extension corn and soybean specialist at the University of Tennessee. “Spread phosphorus, potash, and elemental sulfur on fields during the winter — as long as those fields aren’t prone to flooding or erosion.”
Early planting is generally more conducive to high yields. Wet spring weather across the Mid-South can often lead to stand failures from planting in oversaturated soils, so keep an eye on soil temperatures and long-term weather forecasts.
“Achieving good corn stands is critical, but to optimize yield you need to do more than simply focusing on planting date and seeding rate,” says Dr. Erick Larson, associate Extension and research professor at Mississippi State University. “Our research shows emergence uniformity is important. Rainy and/or cool weather often contribute to variability when corn seedlings emerge, leading to developmental issues that hamper season-long productivity.”
For irrigated corn, optimal plant populations will be higher, somewhere in the 30,000 to 36,000 per acre range. Dryland recommendations normally fall in the 26,000 to 32,000 range. Ranges vary slightly across the Mid-South, with some recommendations a few thousand plants per acre higher. Be mindful that overpopulation can lead to yield reductions. Wide row spacing and late planting can also limit a crop’s responsiveness to plant population.
HYBRID CHOICE IMPORTANT
There is little doubt that the hybrid you choose can make or break a crop. Seed is one of the most expensive inputs. A visit to your state’s hybrid trial evaluation results is time well spent. Here are links to each state’s most recently available hybrid trial results.
- Louisiana: http://bit.ly/2yANSiy
- Tennessee: http://bit.ly/2hYSWGL
- Mississippi: http://bit.ly/2kB9vJJ
- Arkansas: http://bit.ly/2yBCiEc
- Missouri: http://bit.ly/2y7Mxgk
These websites host multiple years of hybrid trials information. Take advantage of company data as well; it can provide important comparative hybrid information offered by the same supplier. Select hybrids for their ability to yield well across different environments, especially on soil types that vary across your operation. Some native trait resistance to stalk rot and gray leaf spot is critical when hybrids are planted under irrigation.
“Consider hybrids that offer insect and disease resistance, good stalk strength, seedling vigor, and overall stress tolerance,” McClure says. “More companies offer a drought tolerance score, which may indicate more efficient water use if planting under dryland conditions.”
Getting corn in the ground early is always a goal, but Mid-South growers often must contend with wet springtime weather. If you start sidedressing when fields are wet, it increases the risk of compaction. “Compaction can have negative effects on root and plant development and could lead to considerable yield loss,” Larson says. “In 2017, even though planting conditions were much better than we’d had in the past, we documented losses ranging from 10 bushels to 20 bushels per acre due to compaction.”
Compaction was a common issue among Louisiana corn farmers in 2016, Fromme says, and many who called his office invested in a penetrometer to more accurately measure and monitor the depth of soil compaction. “Compaction can also lead to declines in water and soil quality from increased runoff and degradation of the soil’s structure.”
Adoption of irrigation moisture management technologies has been steady, but many producers still irrigate based on visual signs of stress, which is unreliable and usually leads to yield loss.
“The real game changer over the last five years has been advancements in these technologies and related software,” says Dr. Ed Barnes, senior director of agricultural and environmental research at Cotton Incorporated. “They now allow irrigation scheduling based on real-time information, delivered through wireless data transfer from buried sensors, via a cell phone modem with a less than $100 per year data plan.”
There are various sensor brands on the market, but most measure physical properties of the soil.
- Soil matric potential measures how tightly water is bound to the soil. Sensors measuring this “potential” include tensiometers and electronic sensors that approximate data from the tensiometers.
- Sensors measuring “volumetric moisture content” evaluate the volume of water per volume of soil. Sensors measuring this physical property include capacitance sensors and neutron probes. For more in-depth information on soil moisture sensors, visit http://bit.ly/2kDNtpN.
Dr. Jason Krutz, irrigation specialist at the Delta Research and Extension Center at Stoneville, Miss., continues to emphasize producer awareness of the unsustainable trend of water level reductions in the Mississippi River Valley alluvial aquifer. “This expansive aquifer stretches underneath all Mid-South states,” he says, “and all farmers utilizing it for irrigation should adopt the latest technologies and tools to help maintain it for the future of farming.”
The three key tools are computerized hole selection (CHS), soil moisture sensors, and surge valves. If a producer is using polypipe to furrow irrigate, CHS (or Delta Pipe’s Pipe Planner) must be in place, or the other two irrigation water management (IWM) tools will not work.
“Water pressure in the polypipe is greater close to the riser,” Krutz notes, “so to triangle out the wetting front and eliminate dry sections of the field, while also preventing water drainage into the tail ditch, those holes have to vary in size, based on certain factors. Using CHS alone can save a farmer $10 an acre in fuel consumption.”
“Veteran farmers know there are no silver bullets,” Fromme cautions. “Base your decisions on good, sound, scientific information, and this will do more to benefit your bottom line at the end of the season.”
Agronomy 101 — SOYBEANS
No other decision will have more impact on your soybean crop than variety choice. All Extension personnel advise reviewing data from your state’s Extension service and from commercial seed companies whose varieties you are considering.
When a grower seeks advice from University of Arkansas System Division of Agriculture Extension Agronomist Jeremy Ross, he has a set of questions ready to ask. They include:
- Which herbicide program do you plan on using (Roundup Ready, Xtend, LibertyLink, conventional, etc.)?
- What’s your field’s soil texture (light sandy, silt loam, heavy clay, etc.)?
- Have you had problems with any particular diseases or nematodes?
- Have you had problems with chlorides in your fields?
“I consider yield as only about 60 percent of the final decision on variety selection,” Ross says, “but once I have some relevant input, I feel more confident making a varietal recommendation.”
Reviewing data on how a variety will perform over multiple environments is critical, especially when an operation has multiple soils. A state’s official variety trials (OVT) are a good place to start.
Louisiana has a “core block program” that evaluates varieties. “The main benefit of this program is that it provides reviews on varieties grown over a large number of in-state environments — 20 locations in 2017,” says Todd Spivey, assistant professor and Extension soybean specialist at the LSU AgCenter. “Growers have the luxury of selecting a variety tested in an environment similar to their farm.”
Can choosing the wrong variety mean lost revenue for a farmer? Without a doubt! Planting the wrong variety can cost an average $60 to $168 an acre in lost yield potential. “Planting a variety that doesn’t perform well in your farm’s environment, when compared against a high-yielding variety with an agronomic match, could cost between $85 and $336 an acre,” says Spivey.
Keep in mind the appropriate maturity group, the date you intend to plant, and based on past weed pressure and level of weed resistance, whether a herbicide-tolerant variety would be cost-effective. Here are links to 2016 Official Soybean Variety Trials for the Mid-South.
- Mississippi: http://bit.ly/1qmjude
- Tennessee: http://bit.ly/2wIVr24
- Missouri: http://bit.ly/2fXhNpQ
- Louisiana: http://bit.ly/2xYFvfl
- Arkansas: http://bit.ly/2xsJgv5
Mid-South Extension personnel agree: When farming margins are tight and input costs are rising, the input many growers eliminate to reduce input costs is fertility.
“Having an effective fertility management program for soybeans is a must,” says Trent Irby, Extension soybean specialist at Mississippi State University. “Nutrient deficiencies can result in reduced yield, and the best way to discover which nutrients are deficient is by soil testing.”
Jeremy Ross advises pulling soil samples every three years, and suggests the following soil nutrient parameters:
- Proper soil pH — greater than 5.8, but preferably around 6.5.
- Potassium — as long as other nutrients are not limiting, soybeans respond most to potassium.
- Phosphorus or boron — usually found at sufficient levels, but soil tests will confirm.
- Micronutrients/secondary nutrients — normally not required too often.
“These are the nutrients central to healthy soybean production,” Ross says. “There has been a push of late toward foliar feeding, but our research hasn’t shown any benefit when a producer has a good preplant fertility program in place.”
On importance scale, planting at the optimum time runs a close second to variety selection. A mid-April to mid-May planting window is recommended to optimize yield potential. Planting past that window can, on average, increase the potential for yield decline. So, if weather allows, start planting in that window.
“There has been a lot of research on planting dates through the years,” Irby says, “but mid- to late April is the sweet spot for getting soybeans in the ground, especially for Group IVs.”
SEEDING RATE, WEEDS
Optimum seeding rates have been researched for many years. As precision planting technologies continue to be adopted, variable rate planting prescriptions, based on grid sampling maps, are optimizing planting efforts for producers who invest in the technology.
“We developed a range of soybean seeding rates, from 100,000 per acre to 180,000 per acre,” Ross says. “Under normal planting conditions, we’ve seen a 95 percent return on a grower’s seed investment with the 100,000 per acre rate. If they plant the upper end of the recommendation, 180,000 per acre, we’ve seen a 100 percent return.”
Many of the growers Ross advises stick to the middle range of those rates, but if they wait to plant in the extremes (early or late) of his recommended planting window, he likes to see them increase seeding rate by 10 percent to 15 percent to insure adequate plant stands.
Over the past few years, some Mid-South growers have seen a yield increase with a combination insecticide/fungicide seed treatment, especially when they plant early or late. While some have reported inconsistent results year-over-year, seed treatments seem to protect and help maintain plant stands during periods of bad weather.
“I realize it may be a toss-up,” Ross says, “but without seed treatments, a grower may face having to replant, which means additional costs, late planting, and possibly reduced yield.”
No matter which crops Mid-South farmers produce, all have to deal with herbicide-resistant weeds. Extension specialists’ advice is short and to the point: Adopt a management approach to weed control from planting to harvest, rather than trying to play catch-up. “Start with a preemerge herbicide and remain observant as soybeans reach maturity and harvest begins,” Irby says. “If you have to hoe to prevent adding to the weed seed bank, do it.”
Dr. Jason Krutz, irrigation specialist at the Delta Research and Extension Center at Stoneville, Miss., is working to create awareness throughout the Mid-South farming community of the downward trend of water in the Mississippi River Valley alluvial aquifer.
The aquifer is losing 300,000 acre feet of water each year — an unsustainable trend. “We urge all producers to adopt three irrigation water management (IWM) tools we know will start us down the path of slowing, and hopefully reversing, that trend: computerized hole selection (CHS), soil moisture sensors, and surge valves,” Krutz says.
By using CHS, he estimates a producer can save around $10 per acre in fuel consumption, which would basically cover the cost of his polypipe.
Agronomy 101 — COTTON
Start any season by evaluating your soil’s fertility levels. Most agronomists recommend conducting soil tests. Providing inputs without knowing if specific nutrient deficiencies exist is costly and impractical.
“In-field nutrient deficiencies seem to be an increasing problem,” says Dan Fromme, associate professor and state cotton and corn specialist at the LSU AgCenter. “Soil test costs are well-justified for the information they provide.”
Realizing some farmers can’t afford all soil test recommendations, Fromme advises supplying the inputs you can afford, or that are most needed, or that will deliver the most return on investment (ROI).
Choosing a Variety
Dr. Darrin Dodds, associate Extension research professor at Mississippi State University, advises all cotton producers to do their homework before spending as much as $650 on a bag of seed. Each year, he evaluates data from over 30 variety trials in Mississippi. “We set up the variety trials with multiple replications, and growers manage the trials throughout the season. That gives us solid data we can then use to provide farmers trusted advice.”
If you compare the highest-yielding variety from these trials against a variety that ended up in the middle of the rankings, a difference in yield and subsequent economic return could be somewhere in the $90 per acre range. “When calculating that on 75 cent cotton, plus the gin rebate, if a grower makes the wrong variety choice, it could cost him between $180 and $200 per acre,” says Dodds.
Links to each Mid-South state’s on-farm trials are:
- Mississippi: http://bit.ly/2yUlST9
- Tennessee: http://bit.ly/2ybBLXW
- Louisiana: http://bit.ly/2kBw6Wv
- Missouri: http://bit.ly/2y61Ic4
- Arkansas: http://bit.ly/2fYNNKy
All Extension specialists recommend one thing: Do your homework, reviewing not only state-supplied data, but seed company data where comparisons are made against their own varieties. “Always consider aspects from your farm’s growing environment and soil type,” says Dodds. Less vigorous varieties are more susceptible to stresses caused by factors like inadequate moisture, cool temperatures, seedling diseases, nematodes, and other pests.
“I would encourage growers to plant resistant varieties, or those that have at least some tolerance,” says Bill Robertson, cotton agronomist with the Arkansas Cooperative Extension Service.
HIGHER QUALITY FIBER
Producers still measure a variety by how it yields, he notes, but mills across the world want higher quality fibers. Extension recommendations warn against selecting a variety simply because it yielded well one year at one location. Some varieties perform more consistently across different seasonal conditions and locations. Identify varietal strengths and weaknesses, and adjust management strategies to enhance those strengths and minimize weaknesses.
“Varieties consistently producing yields near the top of trial rankings are often easier to manage than those that produce at the top in some locations, and in the middle or near the bottom at other locations,” says Robertson. Growers who run their own variety trials should limit those trials to 10 percent of on-farm acres. The bulk of acres should be planted to various proven varieties, with differing maturities, to spread out harvest timings and reduce the risk of weather negatively impacting your entire crop.
Always strive for uniformly-placed seeds (drilled or hill-dropped pattern), with good seed-to-soil contact. Planting with precision, not speed, has proven most effective. The trend in reduced seeding rates reflects producers’ desire to manage high seed costs.
“If you’re planting into cooler soils, increase your seeding rate,” Robertson says. “While planting less than 2 seeds per row foot on 38 inch rows may not necessarily impact yield, it may delay maturity and cost producers precious time because bolls tend to develop more on outer positions and on higher nodes in less dense populations.”
Producers who push the limits of earlier planting have one thing in common: replanting! Planting early doesn’t guarantee earliness. Fungal pathogens flourish at 65 degrees, and the coldest soils are fine-textured, those that drain poorly, flat-planted, and light colored. If you plant into cold soil, use the highest quality seed you can get — and remember, as seed size decreases, seed quality becomes more critical, especially when planting in marginal conditions.
- Select high-quality seed with rapid field germination/emergence potential to narrow the window for seedling diseases and minimize pest impact.
- Plant when midmorning soil temperature is 68 degrees for three consecutive days.
- A favorable five-day forecast following planting is best.
- Soil temps below 50 degrees have been associated with chilling injury of preemerged seeds.
Cotton is an insect-rich crop and lately, Extension professionals have seen many growers with the mindset that just because they are planting two gene Bt cotton, they don’t have to worry about worms.
“Worm outbreaks were common in 2017 — and not just in the Mid-South,” Dodds says. “Have someone in your fields providing current pest pressure numbers to you, and make timely control applications based on scouting. We partially adopted an egg threshold in 2017, and I see that continuing in 2018, depending on the Bt technology contained in the cotton seed you are planting. Caution is urged because once worms become embedded in bloom tags, they can be very difficult to control.”
Across-the-board Extension recommendations advise aggressive weed management, and if you have to chop pigweeds, do it. Any plant left in a field adds viable weed seeds back into the seedbank.
Furrow irrigation dominates across the Mid-South. “Research confirms conventional furrow irrigation is about 50 percent efficient,” says Dr. Jason Krutz, irrigation specialist for the Delta Research and Extension Center at Stoneville, Miss. “Installation of a surge value can boost that efficiency to 75 percent, especially on silt loam soils where crusting often leads to tailwater runoff.”
Krutz encourages all farmers to adopt three irrigation water management (IWM) tools that will help slow that trend: computerized hole selection (CHS) for polypipe; soil moisture sensors; and surge valves. “A 20 percent to 25 percent reduction in water use, and that same percentage reduction in pumping costs, can be realized by adopting IWM tools,” he says.